tcpdump

package: tcpdump

title: tcpdump(8)

summary: dump traffic on a network

text:
# tcpdump(8)

## NAME
tcpdump - dump traffic on a network

## SYNOPSIS
tcpdump [ -AbdDefhHIJKlLnNOpqStuUvxX# ] [ -B buffer_size ]

[ -c count ] [ --count ] [ -C file_size ] [ -E spi@ipaddr algo:secret,... ] [ -F file ] [ -G rotate_seconds ] [ -i interface ] [ --immediate-mode ] [ -j tstamp_type ] [ -m module ] [ -M secret ] [ --number ] [ --print ] [ -Q in|out|inout ] [ -r file ] [ -s snaplen ] [ -T type ] [ --version ] [ -V file ] [ -w file ] [ -W filecount ] [ -y datalinktype ] [ -z postrotate-command ] [ -Z user ] [ --time-stamp-precision=tstamp_precision ] [ --micro ] [ --nano ] [ expression ]

## DESCRIPTION
Tcpdump prints out a description of the contents of packets on a network interface that match the Boolean expression (see pcap-filter(7) for the expression syntax); the description is preceded by a time stamp, printed, by default, as hours, minutes, seconds, and fractions of a second since midnight. It can also be run with the -w flag, which causes it to save the packet data to a file for later analysis, and/or with the -r flag, which causes it to read from a saved packet file rather than to read packets from a network interface. It can also be run with the -V flag, which causes it to read a list of saved packet files. In all cases, only packets that match expression will be processed by tcpdump.

Tcpdump will, if not run with the -c flag, continue capturing packets until it is interrupted by a SIGINT signal (generated, for example, by typing your interrupt character, typically control-C) or a SIGTERM signal (typically generated with the kill(1) command); if run with the -c flag, it will capture packets until it is interrupted by a SIGINT or SIGTERM signal or the specified number of packets have been processed.

When tcpdump finishes capturing packets, it will report counts of:

packets ``captured'' (this is the number of packets that tcpdump has received and processed);

packets ``received by filter'' (the meaning of this depends on the OS on which you're running tcpdump, and possibly on the way the OS was configured - if a filter was specified on the command line, on some OSes it counts packets regardless of whether they were matched by the filter expression and, even if they were matched by the filter expression, regardless of whether tcpdump has read and processed them yet, on other OSes it counts only packets that were matched by the filter expression regardless of whether tcpdump has read and processed them yet, and on other OSes it counts only packets that were matched by the filter expression and were processed by tcpdump);

packets ``dropped by kernel'' (this is the number of packets that were dropped, due to a lack of buffer space, by the packet capture mechanism in the OS on which tcpdump is running, if the OS reports that information to applications; if not, it will be reported as 0).

On platforms that support the SIGINFO signal, such as most BSDs (including macOS) and Digital/Tru64 UNIX, it will report those counts when it receives a SIGINFO signal (generated, for example, by typing your ``status'' character, typically control-T, although on some platforms, such as macOS, the ``status'' character is not set by default, so you must set it with stty(1) in order to use it) and will continue capturing packets. On platforms that do not support the SIGINFO signal, the same can be achieved by using the SIGUSR1 signal.

Using the SIGUSR2 signal along with the -w flag will forcibly flush the packet buffer into the output file.

Reading packets from a network interface may require that you have special privileges; see the pcap(3PCAP) man page for details. Reading a saved packet file doesn't require special privileges.

## OPTIONS
-A

Print each packet (minus its link level header) in ASCII. Handy for capturing web pages.

-b

Print the AS number in BGP packets in ASDOT notation rather than ASPLAIN notation.

-B buffer_size

--buffer-size=buffer_size

Set the operating system capture buffer size to buffer_size, in units of KiB (1024 bytes).

-c count

Exit after receiving count packets.

--count

Print only on stdout the packet count when reading capture file(s) instead of parsing/printing the packets. If a filter is specified on the command line, tcpdump counts only packets that were matched by the filter expression.

-C file_size

Before writing a raw packet to a savefile, check whether the file is currently larger than file_size and, if so, close the current savefile and open a new one. Savefiles after the first savefile will have the name specified with the -w flag, with a number after it, starting at 1 and continuing upward. The units of file_size are millions of bytes (1,000,000 bytes, not 1,048,576 bytes). ALT-specific note: when used with -Z option (enabled by default), privileges are dropped before opening first savefile.

-d

Dump the compiled packet-matching code in a human readable form to standard output and stop.

Please mind that although code compilation is always DLT-specific, typically it is impossible (and unnecessary) to specify which DLT to use for the dump because tcpdump uses either the DLT of the input pcap file specified with -r, or the default DLT of the network interface specified with -i, or the particular DLT of the network interface specified with -y and -i respectively. In these cases the dump shows the same exact code that would filter the input file or the network interface without -d.

However, when neither -r nor -i is specified, specifying -d prevents tcpdump from guessing a suitable network interface (see -i). In this case the DLT defaults to EN10MB and can be set to another valid value manually with -y.

-dd

Dump packet-matching code as a C program fragment.

-ddd

Dump packet-matching code as decimal numbers (preceded with a count).

-D

--list-interfaces

Print the list of the network interfaces available on the system and on which tcpdump can capture packets. For each network interface, a number and an interface name, possibly followed by a text description of the interface, are printed. The interface name or the number can be supplied to the -i flag to specify an interface on which to capture.

This can be useful on systems that don't have a command to list them (e.g., Windows systems, or UNIX systems lacking ifconfig -a); the number can be useful on Windows 2000 and later systems, where the interface name is a somewhat complex string.

The -D flag will not be supported if tcpdump was built with an older version of libpcap that lacks the pcap_findalldevs(3PCAP) function.

-e

Print the link-level header on each dump line. This can be used, for example, to print MAC layer addresses for protocols such as Ethernet and IEEE 802.11.

-E

Use spi@ipaddr algo:secret for decrypting IPsec ESP packets that are addressed to addr and contain Security Parameter Index value spi. This combination may be repeated with comma or newline separation.

Note that setting the secret for IPv4 ESP packets is supported at this time.

Algorithms may be des-cbc, 3des-cbc, blowfish-cbc, rc3-cbc, cast128-cbc, or none. The default is des-cbc. The ability to decrypt packets is only present if tcpdump was compiled with cryptography enabled.

secret is the ASCII text for ESP secret key. If preceded by 0x, then a hex value will be read.

The option assumes RFC 2406 ESP, not RFC 1827 ESP. The option is only for debugging purposes, and the use of this option with a true `secret' key is discouraged. By presenting IPsec secret key onto command line you make it visible to others, via ps(1) and other occasions.

In addition to the above syntax, the syntax file name may be used to have tcpdump read the provided file in. The file is opened upon receiving the first ESP packet, so any special permissions that tcpdump may have been given should already have been given up.

-f

Print `foreign' IPv4 addresses numerically rather than symbolically (this option is intended to get around serious brain damage in Sun's NIS server — usually it hangs forever translating non-local internet numbers).

The test for `foreign' IPv4 addresses is done using the IPv4 address and netmask of the interface on that capture is being done. If that address or netmask are not available, either because the interface on that capture is being done has no address or netmask or because it is the "any" pseudo-interface, which is available in Linux and in recent versions of macOS and Solaris, and which can capture on more than one interface, this option will not work correctly.

-F file

Use file as input for the filter expression. An additional expression given on the command line is ignored.

-G rotate_seconds

If specified, rotates the dump file specified with the -w option every rotate_seconds seconds. Savefiles will have the name specified by -w which should include a time format as defined by strftime(3). If no time format is specified, each new file will overwrite the previous. Whenever a generated filename is not unique, tcpdump will overwrite the pre-existing data; providing a time specification that is coarser than the capture period is therefore not advised.

If used in conjunction with the -C option, filenames will take the form of `file<count>'. ALT-specific note: when used with -Z option (enabled by default), privileges are dropped before opening first savefile.

-h

--help

Print the tcpdump and libpcap version strings, print a usage message, and exit.

--version

Print the tcpdump and libpcap version strings and exit.

-H

Attempt to detect 802.11s draft mesh headers.

-i interface

--interface=interface

Listen, report the list of link-layer types, report the list of time stamp types, or report the results of compiling a filter expression on interface. If unspecified and if the -d flag is not given, tcpdump searches the system interface list for the lowest numbered, configured up interface (excluding loopback), which may turn out to be, for example, ``eth0''.

On Linux systems with 2.2 or later kernels and on recent versions of macOS and Solaris, an interface argument of ``any'' can be used to capture packets from all interfaces. Note that captures on the ``any'' pseudo-interface will not be done in promiscuous mode.

If the -D flag is supported, an interface number as printed by that flag can be used as the interface argument, if no interface on the system has that number as a name.

-I

--monitor-mode

Put the interface in "monitor mode"; this is supported only on IEEE 802.11 Wi-Fi interfaces, and supported only on some operating systems.

Note that in monitor mode the adapter might disassociate from the network with which it's associated, so that you will not be able to use any wireless networks with that adapter. This could prevent accessing files on a network server, or resolving host names or network addresses, if you are capturing in monitor mode and are not connected to another network with another adapter.

This flag will affect the output of the -L flag. If -I isn't specified, only those link-layer types available when not in monitor mode will be shown; if -I is specified, only those link-layer types available when in monitor mode will be shown.

--immediate-mode

Capture in "immediate mode". In this mode, packets are delivered to tcpdump as soon as they arrive, rather than being buffered for efficiency. This is the default when printing packets rather than saving packets to a ``savefile'' if the packets are being printed to a terminal rather than to a file or pipe.

-j tstamp_type

--time-stamp-type=tstamp_type

Set the time stamp type for the capture to tstamp_type. The names to use for the time stamp types are given in pcap-tstamp(7); not all the types listed there will necessarily be valid for any given interface.

-J

--list-time-stamp-types

List the supported time stamp types for the interface and exit. If the time stamp type cannot be set for the interface, no time stamp types are listed.

--time-stamp-precision=tstamp_precision

When capturing, set the time stamp precision for the capture to tstamp_precision. Note that availability of high precision time stamps (nanoseconds) and their actual accuracy is platform and hardware dependent. Also note that when writing captures made with nanosecond accuracy to a savefile, the time stamps are written with nanosecond resolution, and the file is written with a different magic number, to indicate that the time stamps are in seconds and nanoseconds; not all programs that read pcap savefiles will be able to read those captures.

When reading a savefile, convert time stamps to the precision specified by timestamp_precision, and display them with that resolution. If the precision specified is less than the precision of time stamps in the file, the conversion will lose precision.

The supported values for timestamp_precision are micro for microsecond resolution and nano for nanosecond resolution. The default is microsecond resolution.

--micro

--nano

Shorthands for --time-stamp-precision=micro or --time-stamp-precision=nano, adjusting the time stamp precision accordingly. When reading packets from a savefile, using --micro truncates time stamps if the savefile was created with nanosecond precision. In contrast, a savefile created with microsecond precision will have trailing zeroes added to the time stamp when --nano is used.

-K

--dont-verify-checksums

Don't attempt to verify IP, TCP, or UDP checksums. This is useful for interfaces that perform some or all of those checksum calculation in hardware; otherwise, all outgoing TCP checksums will be flagged as bad.

-l

Make stdout line buffered. Useful if you want to see the data while capturing it. E.g.,

```
tcpdump -l | tee dat
```

or

```
tcpdump -l > dat & tail -f dat
```

Note that on Windows,``line buffered'' means ``unbuffered'', so that WinDump will write each character individually if -l is specified.

-U is similar to -l in its behavior, but it will cause output to be ``packet-buffered'', so that the output is written to stdout at the end of each packet rather than at the end of each line; this is buffered on all platforms, including Windows.

-L

--list-data-link-types

List the known data link types for the interface, in the specified mode, and exit. The list of known data link types may be dependent on the specified mode; for example, on some platforms, a Wi-Fi interface might support one set of data link types when not in monitor mode (for example, it might support only fake Ethernet headers, or might support 802.11 headers but not support 802.11 headers with radio information) and another set of data link types when in monitor mode (for example, it might support 802.11 headers, or 802.11 headers with radio information, only in monitor mode).

-m module

Load SMI MIB module definitions from file module. This option can be used several times to load several MIB modules into tcpdump.

-M secret

Use secret as a shared secret for validating the digests found in TCP segments with the TCP-MD5 option (RFC 2385), if present.

-n

Don't convert host addresses to names. This can be used to avoid DNS lookups.

-nn

Don't convert protocol and port numbers etc. to names either.

-N

Don't print domain name qualification of host names. E.g., if you give this flag then tcpdump will print ``nic'' instead of ``nic.ddn.mil''.

-#

--number

Print an optional packet number at the beginning of the line.

-O

--no-optimize

Do not run the packet-matching code optimizer. This is useful only if you suspect a bug in the optimizer.

-p

--no-promiscuous-mode

Don't put the interface into promiscuous mode. Note that the interface might be in promiscuous mode for some other reason; hence, `-p' cannot be used as an abbreviation for `ether host {local-hw-addr} or ether broadcast'.

--print

Print parsed packet output, even if the raw packets are being saved to a file with the -w flag.

-Q direction

--direction=direction

Choose send/receive direction direction for which packets should be captured. Possible values are `in', `out' and `inout'. Not available on all platforms.

-q

Quick (quiet?) output. Print less protocol information so output lines are shorter.

-r file

Read packets from file (which was created with the -w option or by other tools that write pcap or pcapng files). Standard input is used if file is ``-''.

-S

--absolute-tcp-sequence-numbers

Print absolute, rather than relative, TCP sequence numbers.

-s snaplen

--snapshot-length=snaplen

Snarf snaplen bytes of data from each packet rather than the default of 262144 bytes. Packets truncated because of a limited snapshot are indicated in the output with ``[|proto]'', where proto is the name of the protocol level at which the truncation has occurred.

Note that taking larger snapshots both increases the amount of time it takes to process packets and, effectively, decreases the amount of packet buffering. This may cause packets to be lost. Note also that taking smaller snapshots will discard data from protocols above the transport layer, which loses information that may be important. NFS and AFS requests and replies, for example, are very large, and much of the detail won't be available if a too-short snapshot length is selected.

If you need to reduce the snapshot size below the default, you should limit snaplen to the smallest number that will capture the protocol information you're interested in. Setting snaplen to 0 sets it to the default of 262144, for backwards compatibility with recent older versions of tcpdump.

-T type

Force packets selected by "expression" to be interpreted the specified type. Currently known types are aodv (Ad-hoc On-demand Distance Vector protocol), carp (Common Address Redundancy Protocol), cnfp (Cisco NetFlow protocol), domain (Domain Name System), lmp (Link Management Protocol), pgm (Pragmatic General Multicast), pgm_zmtp1 (ZMTP/1.0 inside PGM/EPGM), ptp (Precision Time Protocol), radius (RADIUS), resp (REdis Serialization Protocol), rpc (Remote Procedure Call), rtcp (Real-Time Applications control protocol), rtp (Real-Time Applications protocol), snmp (Simple Network Management Protocol), someip (SOME/IP), tftp (Trivial File Transfer Protocol), vat (Visual Audio Tool), vxlan (Virtual eXtensible Local Area Network), wb (distributed White Board) and zmtp1 (ZeroMQ Message Transport Protocol 1.0).

Note that the pgm type above affects UDP interpretation only, the native PGM is always recognised as IP protocol 113 regardless. UDP-encapsulated PGM is often called "EPGM" or "PGM/UDP".

Note that the pgm_zmtp1 type above affects interpretation of both native PGM and UDP at once. During the native PGM decoding the application data of an ODATA/RDATA packet would be decoded as a ZeroMQ datagram with ZMTP/1.0 frames. During the UDP decoding in addition to that any UDP packet would be treated as an encapsulated PGM packet.

-t

Don't print a timestamp on each dump line.

-tt

Print the timestamp, as seconds since January 1, 1970, 00:00:00, UTC, and fractions of a second since that time, on each dump line.

-ttt

Print a delta (microsecond or nanosecond resolution depending on the --time-stamp-precision option) between current and previous line on each dump line. The default is microsecond resolution.

-tttt

Print a timestamp, as hours, minutes, seconds, and fractions of a second since midnight, preceded by the date, on each dump line.

-ttttt

Print a delta (microsecond or nanosecond resolution depending on the --time-stamp-precision option) between current and first line on each dump line. The default is microsecond resolution.

-u

Print undecoded NFS handles.

-U

--packet-buffered

If the -w option is not specified, or if it is specified but the --print flag is also specified, make the printed packet output ``packet-buffered''; i.e., as the description of the contents of each packet is printed, it will be written to the standard output, rather than, when not writing to a terminal, being written only when the output buffer fills.

If the -w option is specified, make the saved raw packet output ``packet-buffered''; i.e., as each packet is saved, it will be written to the output file, rather than being written only when the output buffer fills.

The -U flag will not be supported if tcpdump was built with an older version of libpcap that lacks the pcap_dump_flush(3PCAP) function.

-v

When parsing and printing, produce (slightly more) verbose output. For example, the time to live, identification, total length and options in an IP packet are printed. Also enables additional packet integrity checks such as verifying the IP and ICMP header checksum.

When writing to a file with the -w option and at the same time not reading from a file with the -r option, report to stderr, once per second, the number of packets captured. In Solaris, FreeBSD and possibly other operating systems this periodic update currently can cause loss of captured packets on their way from the kernel to tcpdump.

-vv

Even more verbose output. For example, additional fields are printed from NFS reply packets, and SMB packets are fully decoded.

-vvv

Even more verbose output. For example, telnet SB ... SE options are printed in full. With -X Telnet options are printed in hex as well.

-V file

Read a list of filenames from file. Standard input is used if file is ``-''.

-w file

Write the raw packets to file rather than parsing and printing them out. They can later be printed with the -r option. Standard output is used if file is ``-''.

This output will be buffered if written to a file or pipe, so a program reading from the file or pipe may not see packets for an arbitrary amount of time after they are received. Use the -U flag to cause packets to be written as soon as they are received.

The MIME type application/vnd.tcpdump.pcap has been registered with IANA for pcap files. The filename extension .pcap appears to be the most commonly used along with .cap and .dmp. Tcpdump itself doesn't check the extension when reading capture files and doesn't add an extension when writing them (it uses magic numbers in the file header instead). However, many operating systems and applications will use the extension if it is present and adding one (e.g. .pcap) is recommended.

See pcap-savefile(5) for a description of the file format.

-W filecount

Used in conjunction with the -C option, this will limit the number of files created to the specified number, and begin overwriting files from the beginning, thus creating a 'rotating' buffer. In addition, it will name the files with enough leading 0s to support the maximum number of files, allowing them to sort correctly.

Used in conjunction with the -G option, this will limit the number of rotated dump files that get created, exiting with status 0 when reaching the limit.

If used in conjunction with both -C and -G, the -W option will currently be ignored, and will only affect the file name.

-x

When parsing and printing, in addition to printing the headers of each packet, print the data of each packet (minus its link level header) in hex. The smaller of the entire packet or snaplen bytes will be printed. Note that this is the entire link-layer packet, so for link layers that pad (e.g. Ethernet), the padding bytes will also be printed when the higher layer packet is shorter than the required padding. In the current implementation this flag may have the same effect as -xx if the packet is truncated.

-xx

When parsing and printing, in addition to printing the headers of each packet, print the data of each packet, including its link level header, in hex.

-X

When parsing and printing, in addition to printing the headers of each packet, print the data of each packet (minus its link level header) in hex and ASCII. This is very handy for analysing new protocols. In the current implementation this flag may have the same effect as -XX if the packet is truncated.

-XX

When parsing and printing, in addition to printing the headers of each packet, print the data of each packet, including its link level header, in hex and ASCII.

-y datalinktype

--linktype=datalinktype

Set the data link type to use while capturing packets (see -L) or just compiling and dumping packet-matching code (see -d) to datalinktype.

-z postrotate-command

Used in conjunction with the -C or -G options, this will make tcpdump run " postrotate-command file " where file is the savefile being closed after each rotation. For example, specifying -z gzip or -z bzip2 will compress each savefile using gzip or bzip2.

Note that tcpdump will run the command in parallel to the capture, using the lowest priority so that this doesn't disturb the capture process.

And in case you would like to use a command that itself takes flags or different arguments, you can always write a shell script that will take the savefile name as the only argument, make the flags & arguments arrangements and execute the command that you want.

-Z user

--relinquish-privileges=user

If tcpdump is running as root, after opening the capture device or input savefile, but before opening any savefiles for output, change the user ID to user and the group ID to the primary group of user.

This behavior is enabled by default (-Z tcpdump), and can be disabled by -Z root.

expression

selects which packets will be dumped. If no expression is given, all packets on the net will be dumped. Otherwise, only packets for which expression is `true' will be dumped. For the expression syntax, see pcap-filter(7).

The expression argument can be passed to tcpdump as either a single Shell argument, or as multiple Shell arguments, whichever is more convenient. Generally, if the expression contains Shell metacharacters, such as backslashes used to escape protocol names, it is easier to pass it as a single, quoted argument rather than to escape the Shell metacharacters. Multiple arguments are concatenated with spaces before being parsed.

## EXAMPLES
To print all packets arriving at or departing from sundown:

```
tcpdump host sundown
```

To print traffic between helios and either hot or ace:

```
tcpdump host helios and \( hot or ace \)
```

To print all IP packets between ace and any host except helios:

```
tcpdump ip host ace and not helios
```

To print all traffic between local hosts and hosts at Berkeley:

```
tcpdump net ucb-ether
```

To print all ftp traffic through internet gateway snup: (note that the expression is quoted to prevent the shell from (mis-)interpreting the parentheses):

```
tcpdump 'gateway snup and (port ftp or ftp-data)'
```

To print traffic neither sourced from nor destined for local hosts (if you gateway to one other net, this stuff should never make it onto your local net).

```
tcpdump ip and not net localnet
```

To print the start and end packets (the SYN and FIN packets) of each TCP conversation that involves a non-local host.

```
tcpdump 'tcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net localnet'
```

To print the TCP packets with flags RST and ACK both set. (i.e. select only the RST and ACK flags in the flags field, and if the result is "RST and ACK both set", match)

```
tcpdump 'tcp[tcpflags] & (tcp-rst|tcp-ack) == (tcp-rst|tcp-ack)'
```

To print all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain data, not, for example, SYN and FIN packets and ACK-only packets. (IPv6 is left as an exercise for the reader.)

```
tcpdump 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'
```

To print IP packets longer than 576 bytes sent through gateway snup:

```
tcpdump 'gateway snup and ip[2:2] > 576'
```

To print IP broadcast or multicast packets that were not sent via Ethernet broadcast or multicast:

```
tcpdump 'ether[0] & 1 = 0 and ip[16] >= 224'
```

To print all ICMP packets that are not echo requests/replies (i.e., not ping packets):

```
tcpdump 'icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply'
```

## OUTPUT FORMAT
The output of tcpdump is protocol dependent. The following gives a brief description and examples of most of the formats.

Timestamps

By default, all output lines are preceded by a timestamp. The timestamp is the current clock time in the form

```
hh:mm:ss.frac
```

and is as accurate as the kernel's clock. The timestamp reflects the time the kernel applied a time stamp to the packet. No attempt is made to account for the time lag between when the network interface finished receiving the packet from the network and when the kernel applied a time stamp to the packet; that time lag could include a delay between the time when the network interface finished receiving a packet from the network and the time when an interrupt was delivered to the kernel to get it to read the packet and a delay between the time when the kernel serviced the `new packet' interrupt and the time when it applied a time stamp to the packet. Link Level Headers

If the '-e' option is given, the link level header is printed out. On Ethernets, the source and destination addresses, protocol, and packet length are printed.

On FDDI networks, the '-e' option causes tcpdump to print the `frame control' field, the source and destination addresses, and the packet length. (The `frame control' field governs the interpretation of the rest of the packet. Normal packets (such as those containing IP datagrams) are `async' packets, with a priority value between 0 and 7; for example, `async4'. Such packets are assumed to contain an 802.2 Logical Link Control (LLC) packet; the LLC header is printed if it is not an ISO datagram or a so-called SNAP packet.

On Token Ring networks, the '-e' option causes tcpdump to print the `access control' and `frame control' fields, the source and destination addresses, and the packet length. As on FDDI networks, packets are assumed to contain an LLC packet. Regardless of whether the '-e' option is specified or not, the source routing information is printed for source-routed packets.

On 802.11 networks, the '-e' option causes tcpdump to print the `frame control' fields, all of the addresses in the 802.11 header, and the packet length. As on FDDI networks, packets are assumed to contain an LLC packet.

(N.B.: The following description assumes familiarity with the SLIP compression algorithm described in RFC 1144.)

On SLIP links, a direction indicator (``I'' for inbound, ``O'' for outbound), packet type, and compression information are printed out. The packet type is printed first. The three types are ip, utcp, and ctcp. No further link information is printed for ip packets. For TCP packets, the connection identifier is printed following the type. If the packet is compressed, its encoded header is printed out. The special cases are printed out as *S+n and *SA+n, where n is the amount by which the sequence number (or sequence number and ack) has changed. If it is not a special case, zero or more changes are printed. A change is indicated by U (urgent pointer), W (window), A (ack), S (sequence number), and I (packet ID), followed by a delta (+n or -n), or a new value (=n). Finally, the amount of data in the packet and compressed header length are printed.

For example, the following line shows an outbound compressed TCP packet, with an implicit connection identifier; the ack has changed by 6, the sequence number by 49, and the packet ID by 6; there are 3 bytes of data and 6 bytes of compressed header:

```
O ctcp * A+6 S+49 I+6 3 (6)
```

ARP/RARP Packets

ARP/RARP output shows the type of request and its arguments. The format is intended to be self explanatory. Here is a short sample taken from the start of an `rlogin' from host rtsg to host csam:

```
arp who-has csam tell rtsg
arp reply csam is-at CSAM
```

The first line says that rtsg sent an ARP packet asking for the Ethernet address of internet host csam. Csam replies with its Ethernet address (in this example, Ethernet addresses are in caps and internet addresses in lower case). This would look less redundant if we had done tcpdump -n:

```
arp who-has 128.3.254.6 tell 128.3.254.68
arp reply 128.3.254.6 is-at 02:07:01:00:01:c4
```

If we had done tcpdump -e, the fact that the first packet is broadcast and the second is point-to-point would be visible:

```
RTSG Broadcast 0806  64: arp who-has csam tell rtsg
CSAM RTSG 0806  64: arp reply csam is-at CSAM
```

For the first packet this says the Ethernet source address is RTSG, the destination is the Ethernet broadcast address, the type field contained hex 0806 (type ETHER_ARP) and the total length was 64 bytes. IPv4 Packets

If the link-layer header is not being printed, for IPv4 packets, IP is printed after the time stamp.

If the -v flag is specified, information from the IPv4 header is shown in parentheses after the IP or the link-layer header. The general format of this information is:

```
tos tos, ttl ttl, id id, offset offset, flags [flags], proto proto, length length, options (options)
```

tos is the type of service field; if the ECN bits are non-zero, those are reported as ECT(1), ECT(0), or CE. ttl is the time-to-live; it is not reported if it is zero. id is the IP identification field. offset is the fragment offset field; it is printed whether this is part of a fragmented datagram or not. flags are the MF and DF flags; + is reported if MF is set, and DF is reported if F is set. If neither are set, . is reported. proto is the protocol ID field. length is the total length field. options are the IP options, if any. Next, for TCP and UDP packets, the source and destination IP addresses and TCP or UDP ports, with a dot between each IP address and its corresponding port, will be printed, with a > separating the source and destination. For other protocols, the addresses will be printed, with a > separating the source and destination. Higher level protocol information, if any, will be printed after that.

For fragmented IP datagrams, the first fragment contains the higher level protocol header; fragments after the first contain no higher level protocol header. Fragmentation information will be printed only with the -v flag, in the IP header information, as described above.

TCP Packets

(N.B.:The following description assumes familiarity with the TCP protocol described in RFC 793. If you are not familiar with the protocol, this description will not be of much use to you.)

The general format of a TCP protocol line is:

```
src > dst: Flags [tcpflags], seq data-seqno, ack ackno, win window, urg urgent, options [opts], length len
```

Src and dst are the source and destination IP addresses and ports. Tcpflags are some combination of S (SYN), F (FIN), P (PSH), R (RST), U (URG), W (CWR), E (ECE) or `.' (ACK), or `none' if no flags are set. Data-seqno describes the portion of sequence space covered by the data in this packet (see example below). Ackno is sequence number of the next data expected the other direction on this connection. Window is the number of bytes of receive buffer space available the other direction on this connection. Urg indicates there is `urgent' data in the packet. Opts are TCP options (e.g., mss 1024). Len is the length of payload data. Iptype, Src, dst, and flags are always present. The other fields depend on the contents of the packet's TCP protocol header and are output only if appropriate.

Here is the opening portion of an rlogin from host rtsg to host csam.

```
IP rtsg.1023 > csam.login: Flags [S], seq 768512:768512, win 4096, opts [mss 1024]
IP csam.login > rtsg.1023: Flags [S.], seq, 947648:947648, ack 768513, win 4096, opts [mss 1024]
IP rtsg.1023 > csam.login: Flags [.], ack 1, win 4096
IP rtsg.1023 > csam.login: Flags [P.], seq 1:2, ack 1, win 4096, length 1
IP csam.login > rtsg.1023: Flags [.], ack 2, win 4096
IP rtsg.1023 > csam.login: Flags [P.], seq 2:21, ack 1, win 4096, length 19
IP csam.login > rtsg.1023: Flags [P.], seq 1:2, ack 21, win 4077, length 1
IP csam.login > rtsg.1023: Flags [P.], seq 2:3, ack 21, win 4077, urg 1, length 1
IP csam.login > rtsg.1023: Flags [P.], seq 3:4, ack 21, win 4077, urg 1, length 1
```

The first line says that TCP port 1023 on rtsg sent a packet to port login on csam. The S indicates that the SYN flag was set. The packet sequence number was 768512 and it contained no data. (The notation is `first:last' which means `sequence numbers first up to but not including last'.) There was no piggy-backed ACK, the available receive window was 4096 bytes and there was a max-segment-size option requesting an MSS of 1024 bytes. Csam replies with a similar packet except it includes a piggy-backed ACK for rtsg's SYN. Rtsg then ACKs csam's SYN. The `.' means the ACK flag was set. The packet contained no data so there is no data sequence number or length. Note that the ACK sequence number is a small integer (1). The first time tcpdump sees a TCP `conversation', it prints the sequence number from the packet. On subsequent packets of the conversation, the difference between the current packet's sequence number and this initial sequence number is printed. This means that sequence numbers after the first can be interpreted as relative byte positions in the conversation's data stream (with the first data byte each direction being `1'). `-S' will override this feature, causing the original sequence numbers to be output.

On the 6th line, rtsg sends csam 19 bytes of data (bytes 2 through 20 in the rtsg → csam side of the conversation). The PSH flag is set in the packet. On the 7th line, csam says it's received data sent by rtsg up to but not including byte 21. Most of this data is apparently sitting in the socket buffer since csam's receive window has gotten 19 bytes smaller. Csam also sends one byte of data to rtsg in this packet. On the 8th and 9th lines, csam sends two bytes of urgent, pushed data to rtsg.

If the snapshot was small enough that tcpdump didn't capture the full TCP header, it interprets as much of the header as it can and then reports ``[|tcp]'' to indicate the remainder could not be interpreted. If the header contains a bogus option (one with a length that's either too small or beyond the end of the header), tcpdump reports it as ``[bad opt]'' and does not interpret any further options (since it's impossible to tell where they start). If the header length indicates options are present but the IP datagram length is not long enough for the options to actually be there, tcpdump reports it as ``[bad hdr length]''.

Capturing TCP packets with particular flag combinations (SYN-ACK, URG-ACK, etc.)

There are 8 bits in the control bits section of the TCP header:

CWR | ECE | URG | ACK | PSH | RST | SYN | FIN

Let's assume that we want to watch packets used in establishing a TCP connection. Recall that TCP uses a 3-way handshake protocol when it initializes a new connection; the connection sequence with regard to the TCP control bits is

1) Caller sends SYN

2) Recipient responds with SYN, ACK

3) Caller sends ACK

Now we're interested in capturing packets that have only the SYN bit set (Step 1). Note that we don't want packets from step 2 (SYN-ACK), just a plain initial SYN. What we need is a correct filter expression for tcpdump.

Recall the structure of a TCP header without options:

```
 0                            15                              31
-----------------------------------------------------------------
|          source port          |       destination port        |
-----------------------------------------------------------------
|                        sequence number                        |
-----------------------------------------------------------------
|                     acknowledgment number                     |
-----------------------------------------------------------------
|  HL   | rsvd  |C|E|U|A|P|R|S|F|        window size            |
-----------------------------------------------------------------
|         TCP checksum          |       urgent pointer          |
-----------------------------------------------------------------
```

A TCP header usually holds 20 octets of data, unless options are present. The first line of the graph contains octets 0 - 3, the second line shows octets 4 - 7 etc.

Starting to count with 0, the relevant TCP control bits are contained in octet 13:

```
 0             7|             15|             23|             31
----------------|---------------|---------------|----------------
|  HL   | rsvd  |C|E|U|A|P|R|S|F|        window size            |
----------------|---------------|---------------|----------------
|               |  13th octet   |               |               |
```

Let's have a closer look at octet no. 13:

```
                |               |

                |---------------|

                |C|E|U|A|P|R|S|F|

                |---------------|

                |7   5   3     0|
```

These are the TCP control bits we are interested in. We have numbered the bits in this octet from 0 to 7, right to left, so the PSH bit is bit number 3, while the URG bit is number 5.

Recall that we want to capture packets with only SYN set. Let's see what happens to octet 13 if a TCP datagram arrives with the SYN bit set in its header:

```
                |C|E|U|A|P|R|S|F|

                |---------------|

                |0 0 0 0 0 0 1 0|

                |---------------|

                |7 6 5 4 3 2 1 0|
```

Looking at the control bits section we see that only bit number 1 (SYN) is set.

Assuming that octet number 13 is an 8-bit unsigned integer in network byte order, the binary value of this octet is

00000010

and its decimal representation is

```
   7     6     5     4     3     2     1     0
0*2 + 0*2 + 0*2 + 0*2 + 0*2 + 0*2 + 1*2 + 0*2  =  2
```

We're almost done, because now we know that if only SYN is set, the value of the 13th octet in the TCP header, when interpreted as a 8-bit unsigned integer in network byte order, must be exactly 2.

This relationship can be expressed as

tcp[13] == 2

We can use this expression as the filter for tcpdump in order to watch packets which have only SYN set:

tcpdump -i xl0 tcp[13] == 2

The expression says "let the 13th octet of a TCP datagram have the decimal value 2", which is exactly what we want.

Now, let's assume that we need to capture SYN packets, but we don't care if ACK or any other TCP control bit is set at the same time. Let's see what happens to octet 13 when a TCP datagram with SYN-ACK set arrives:

```
     |C|E|U|A|P|R|S|F|

     |---------------|

     |0 0 0 1 0 0 1 0|

     |---------------|

     |7 6 5 4 3 2 1 0|
```

Now bits 1 and 4 are set in the 13th octet. The binary value of octet 13 is

00010010

which translates to decimal

```
   7     6     5     4     3     2     1     0
0*2 + 0*2 + 0*2 + 1*2 + 0*2 + 0*2 + 1*2 + 0*2   = 18
```

Now we can't just use 'tcp[13] == 18' in the tcpdump filter expression, because that would select only those packets that have SYN-ACK set, but not those with only SYN set. Remember that we don't care if ACK or any other control bit is set as long as SYN is set.

In order to achieve our goal, we need to logically AND the binary value of octet 13 with some other value to preserve the SYN bit. We know that we want SYN to be set in any case, so we'll logically AND the value in the 13th octet with the binary value of a SYN:

```
          00010010 SYN-ACK              00000010 SYN

     AND  00000010 (we want SYN)   AND  00000010 (we want SYN)

          --------                      --------

     =    00000010                 =    00000010
```

We see that this AND operation delivers the same result regardless whether ACK or another TCP control bit is set. The decimal representation of the AND value as well as the result of this operation is 2 (binary 00000010), so we know that for packets with SYN set the following relation must hold true:

( ( value of octet 13 ) AND ( 2 ) ) == ( 2 )

This points us to the tcpdump filter expression

tcpdump -i xl0 'tcp[13] & 2 == 2'

Some offsets and field values may be expressed as names rather than as numeric values. For example tcp[13] may be replaced with tcp[tcpflags]. The following TCP flag field values are also available: tcp-fin, tcp-syn, tcp-rst, tcp-push, tcp-ack, tcp-urg, tcp-ece and tcp-cwr.

This can be demonstrated as:

tcpdump -i xl0 'tcp[tcpflags] & tcp-push != 0'

Note that you should use single quotes or a backslash in the expression to hide the AND ('&') special character from the shell.

UDP Packets

UDP format is illustrated by this rwho packet:

```
actinide.who > broadcast.who: udp 84
```

This says that port who on host actinide sent a UDP datagram to port who on host broadcast, the Internet broadcast address. The packet contained 84 bytes of user data. Some UDP services are recognized (from the source or destination port number) and the higher level protocol information printed. In particular, Domain Name service requests (RFC 1034/1035) and Sun RPC calls (RFC 1050) to NFS.

TCP or UDP Name Server Requests

(N.B.:The following description assumes familiarity with the Domain Service protocol described in RFC 1035. If you are not familiar with the protocol, the following description will appear to be written in Greek.)

Name server requests are formatted as

```
src > dst: id op? flags qtype qclass name (len)

h2opolo.1538 > helios.domain: 3+ A? ucbvax.berkeley.edu. (37)
```

Host h2opolo asked the domain server on helios for an address record (qtype=A) associated with the name ucbvax.berkeley.edu. The query id was `3'. The `+' indicates the recursion desired flag was set. The query length was 37 bytes, excluding the TCP or UDP and IP protocol headers. The query operation was the normal one, Query, so the op field was omitted. If the op had been anything else, it would have been printed between the `3' and the `+'. Similarly, the qclass was the normal one, C_IN, and omitted. Any other qclass would have been printed immediately after the `A'. A few anomalies are checked and may result in extra fields enclosed in square brackets: If a query contains an answer, authority records or additional records section, ancount, nscount, or arcount are printed as `[na]', `[nn]' or `[nau]' where n is the appropriate count. If any of the response bits are set (AA, RA or rcode) or any of the `must be zero' bits are set in bytes two and three, `[b2&3=x]' is printed, where x is the hex value of header bytes two and three.

TCP or UDP Name Server Responses

Name server responses are formatted as

```
src > dst:  id op rcode flags a/n/au type class data (len)

helios.domain > h2opolo.1538: 3 3/3/7 A 128.32.137.3 (273)
helios.domain > h2opolo.1537: 2 NXDomain* 0/1/0 (97)
```

In the first example, helios responds to query id 3 from h2opolo with 3 answer records, 3 name server records and 7 additional records. The first answer record is type A (address) and its data is internet address 128.32.137.3. The total size of the response was 273 bytes, excluding TCP or UDP and IP headers. The op (Query) and response code (NoError) were omitted, as was the class (C_IN) of the A record. In the second example, helios responds to query 2 with a response code of non-existent domain (NXDomain) with no answers, one name server and no authority records. The `*' indicates that the authoritative answer bit was set. Since there were no answers, no type, class or data were printed.

Other flag characters that might appear are `-' (recursion available, RA, not set) and `|' (truncated message, TC, set). If the `question' section doesn't contain exactly one entry, `[nq]' is printed.

SMB/CIFS decoding

tcpdump now includes fairly extensive SMB/CIFS/NBT decoding for data on UDP/137, UDP/138 and TCP/139. Some primitive decoding of IPX and NetBEUI SMB data is also done.

By default a fairly minimal decode is done, with a much more detailed decode done if -v is used. Be warned that with -v a single SMB packet may take up a page or more, so only use -v if you really want all the gory details.

For information on SMB packet formats and what all the fields mean see https://download.samba.org/pub/samba/specs/ and other online resources. The SMB patches were written by Andrew Tridgell (tridge@samba.org).

NFS Requests and Replies

Sun NFS (Network File System) requests and replies are printed as:

```
src.sport > dst.nfs: NFS request xid xid len op args
src.nfs > dst.dport: NFS reply xid xid reply stat len op results

sushi.1023 > wrl.nfs: NFS request xid 26377
	112 readlink fh 21,24/10.73165
wrl.nfs > sushi.1023: NFS reply xid 26377
	reply ok 40 readlink "../var"
sushi.1022 > wrl.nfs: NFS request xid 8219
	144 lookup fh 9,74/4096.6878 "xcolors"
wrl.nfs > sushi.1022: NFS reply xid 8219
	reply ok 128 lookup fh 9,74/4134.3150
```

In the first line, host sushi sends a transaction with id 26377 to wrl. The request was 112 bytes, excluding the UDP and IP headers. The operation was a readlink (read symbolic link) on file handle (fh) 21,24/10.731657119. (If one is lucky, as in this case, the file handle can be interpreted as a major,minor device number pair, followed by the inode number and generation number.) In the second line, wrl replies `ok' with the same transaction id and the contents of the link. In the third line, sushi asks (using a new transaction id) wrl to lookup the name `xcolors' in directory file 9,74/4096.6878. In the fourth line, wrl sends a reply with the respective transaction id.

Note that the data printed depends on the operation type. The format is intended to be self explanatory if read in conjunction with an NFS protocol spec. Also note that older versions of tcpdump printed NFS packets in a slightly different format: the transaction id (xid) would be printed instead of the non-NFS port number of the packet.

If the -v (verbose) flag is given, additional information is printed. For example:

```
sushi.1023 > wrl.nfs: NFS request xid 79658
	148 read fh 21,11/12.195 8192 bytes @ 24576
wrl.nfs > sushi.1023: NFS reply xid 79658
	reply ok 1472 read REG 100664 ids 417/0 sz 29388
```

(-v also prints the IP header TTL, ID, length, and fragmentation fields, which have been omitted from this example.) In the first line, sushi asks wrl to read 8192 bytes from file 21,11/12.195, at byte offset 24576. Wrl replies `ok'; the packet shown on the second line is the first fragment of the reply, and hence is only 1472 bytes long (the other bytes will follow in subsequent fragments, but these fragments do not have NFS or even UDP headers and so might not be printed, depending on the filter expression used). Because the -v flag is given, some of the file attributes (which are returned in addition to the file data) are printed: the file type (``REG'', for regular file), the file mode (in octal), the UID and GID, and the file size. If the -v flag is given more than once, even more details are printed.

NFS reply packets do not explicitly identify the RPC operation. Instead, tcpdump keeps track of ``recent'' requests, and matches them to the replies using the transaction ID. If a reply does not closely follow the corresponding request, it might not be parsable.

AFS Requests and Replies

Transarc AFS (Andrew File System) requests and replies are printed as:

```
src.sport > dst.dport: rx packet-type
src.sport > dst.dport: rx packet-type service call call-name args
src.sport > dst.dport: rx packet-type service reply call-name args

elvis.7001 > pike.afsfs:
	rx data fs call rename old fid 536876964/1/1 ".newsrc.new"
	new fid 536876964/1/1 ".newsrc"
pike.afsfs > elvis.7001: rx data fs reply rename
```

In the first line, host elvis sends a RX packet to pike. This was a RX data packet to the fs (fileserver) service, and is the start of an RPC call. The RPC call was a rename, with the old directory file id of 536876964/1/1 and an old filename of `.newsrc.new', and a new directory file id of 536876964/1/1 and a new filename of `.newsrc'. The host pike responds with a RPC reply to the rename call (which was successful, because it was a data packet and not an abort packet). In general, all AFS RPCs are decoded at least by RPC call name. Most AFS RPCs have at least some of the arguments decoded (generally only the `interesting' arguments, for some definition of interesting).

The format is intended to be self-describing, but it will probably not be useful to people who are not familiar with the workings of AFS and RX.

If the -v (verbose) flag is given twice, acknowledgement packets and additional header information is printed, such as the RX call ID, call number, sequence number, serial number, and the RX packet flags.

If the -v flag is given twice, additional information is printed, such as the RX call ID, serial number, and the RX packet flags. The MTU negotiation information is also printed from RX ack packets.

If the -v flag is given three times, the security index and service id are printed.

Error codes are printed for abort packets, with the exception of Ubik beacon packets (because abort packets are used to signify a yes vote for the Ubik protocol).

AFS reply packets do not explicitly identify the RPC operation. Instead, tcpdump keeps track of ``recent'' requests, and matches them to the replies using the call number and service ID. If a reply does not closely follow the corresponding request, it might not be parsable.

KIP AppleTalk (DDP in UDP)

AppleTalk DDP packets encapsulated in UDP datagrams are de-encapsulated and dumped as DDP packets (i.e., all the UDP header information is discarded). The file /etc/atalk.names is used to translate AppleTalk net and node numbers to names. Lines in this file have the form

```
number	name
1.254		ether
16.1		icsd-net
1.254.110	ace
```

The first two lines give the names of AppleTalk networks. The third line gives the name of a particular host (a host is distinguished from a net by the 3rd octet in the number - a net number must have two octets and a host number must have three octets.) The number and name should be separated by whitespace (blanks or tabs). The /etc/atalk.names file may contain blank lines or comment lines (lines starting with a `#'). AppleTalk addresses are printed in the form

```
net.host.port
144.1.209.2 > icsd-net.112.220
office.2 > icsd-net.112.220
jssmag.149.235 > icsd-net.2
```

(If the /etc/atalk.names doesn't exist or doesn't contain an entry for some AppleTalk host/net number, addresses are printed in numeric form.) In the first example, NBP (DDP port 2) on net 144.1 node 209 is sending to whatever is listening on port 220 of net icsd node 112. The second line is the same except the full name of the source node is known (`office'). The third line is a send from port 235 on net jssmag node 149 to broadcast on the icsd-net NBP port (note that the broadcast address (255) is indicated by a net name with no host number - for this reason it's a good idea to keep node names and net names distinct in /etc/atalk.names). NBP (name binding protocol) and ATP (AppleTalk transaction protocol) packets have their contents interpreted. Other protocols just dump the protocol name (or number if no name is registered for the protocol) and packet size.

NBP packets are formatted like the following examples:

```
icsd-net.112.220 > jssmag.2: nbp-lkup 190: "=:LaserWriter@*"
jssmag.209.2 > icsd-net.112.220: nbp-reply 190: "RM1140:LaserWriter@*" 250
techpit.2 > icsd-net.112.220: nbp-reply 190: "techpit:LaserWriter@*" 186
```

The first line is a name lookup request for laserwriters sent by net icsd host 112 and broadcast on net jssmag. The nbp id for the lookup is 190. The second line shows a reply for this request (note that it has the same id) from host jssmag.209 saying that it has a laserwriter resource named "RM1140" registered on port 250. The third line is another reply to the same request saying host techpit has laserwriter "techpit" registered on port 186. ATP packet formatting is demonstrated by the following example:

```
jssmag.209.165 > helios.132: atp-req  12266<0-7> 0xae030001
helios.132 > jssmag.209.165: atp-resp 12266:0 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:1 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:2 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:3 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:4 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:5 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:6 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp*12266:7 (512) 0xae040000
jssmag.209.165 > helios.132: atp-req  12266<3,5> 0xae030001
helios.132 > jssmag.209.165: atp-resp 12266:3 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:5 (512) 0xae040000
jssmag.209.165 > helios.132: atp-rel  12266<0-7> 0xae030001
jssmag.209.133 > helios.132: atp-req* 12267<0-7> 0xae030002
```

Jssmag.209 initiates transaction id 12266 with host helios by requesting up to 8 packets (the `<0-7>'). The hex number at the end of the line is the value of the `userdata' field in the request. Helios responds with 8 512-byte packets. The `:digit' following the transaction id gives the packet sequence number in the transaction and the number in parens is the amount of data in the packet, excluding the ATP header. The `*' on packet 7 indicates that the EOM bit was set.

Jssmag.209 then requests that packets 3 & 5 be retransmitted. Helios resends them then jssmag.209 releases the transaction. Finally, jssmag.209 initiates the next request. The `*' on the request indicates that XO (`exactly once') was not set.

## BACKWARD COMPATIBILITY
The TCP flag names tcp-ece and tcp-cwr became available when linking with libpcap 1.9.0 or later.

## SEE ALSO
stty(1), pcap(3PCAP), bpf(4), nit(4P), pcap-savefile(5), pcap-filter(7), pcap-tstamp(7)

https://www.iana.org/assignments/media-types/application/vnd.tcpdump.pcap

## AUTHORS
The original authors are:

Van Jacobson, Craig Leres and Steven McCanne, all of the Lawrence Berkeley National Laboratory, University of California, Berkeley, CA.

It is currently maintained by The Tcpdump Group.

The current version is available via HTTPS:

https://www.tcpdump.org/

The original distribution is available via anonymous ftp:

ftp://ftp.ee.lbl.gov/old/tcpdump.tar.Z

IPv6/IPsec support is added by WIDE/KAME project. This program uses OpenSSL/LibreSSL, under specific configurations.

## BUGS
To report a security issue please send an e-mail to security@tcpdump.org.

To report bugs and other problems, contribute patches, request a feature, provide generic feedback etc. please see the file CONTRIBUTING.md in the tcpdump source tree root.

NIT doesn't let you watch your own outbound traffic, BPF will. We recommend that you use the latter.

On Linux systems with 2.0[.x] kernels:

packets on the loopback device will be seen twice;

packet filtering cannot be done in the kernel, so that all packets must be copied from the kernel in order to be filtered in user mode;

all of a packet, not just the part that's within the snapshot length, will be copied from the kernel (the 2.0[.x] packet capture mechanism, if asked to copy only part of a packet to userspace, will not report the true length of the packet; this would cause most IP packets to get an error from tcpdump);

capturing on some PPP devices won't work correctly.

We recommend that you upgrade to a 2.2 or later kernel.

Some attempt should be made to reassemble IP fragments or, at least to compute the right length for the higher level protocol.

Name server inverse queries are not dumped correctly: the (empty) question section is printed rather than real query in the answer section. Some believe that inverse queries are themselves a bug and prefer to fix the program generating them rather than tcpdump.

A packet trace that crosses a daylight savings time change will give skewed time stamps (the time change is ignored).

Filter expressions on fields other than those in Token Ring headers will not correctly handle source-routed Token Ring packets.

Filter expressions on fields other than those in 802.11 headers will not correctly handle 802.11 data packets with both To DS and From DS set.

ip6 proto should chase header chain, but at this moment it does not. ip6 protochain is supplied for this behavior.

Arithmetic expression against transport layer headers, like tcp[0], does not work against IPv6 packets. It only looks at IPv4 packets.


tcplay

package: tcplay

title: tcplay(8)

summary: tool to manage TrueCrypt volumes

text:
# tcplay(8)

## NAME
tcplay — tool to manage TrueCrypt volumes

## SYNOPSIS
tcplay

-c -d device [-g] [-z] [-w] [-a pbkdf_hash] [-b cipher] [-f keyfile_hidden] [-k keyfile] [-x pbkdf_hash] [-y cipher]

tcplay

-i -d device [-e] [-f keyfile_hidden] [-k keyfile] [-s system_device] [--fde] [--use-backup] [--use-hdr-file hdr_file] [--use-hidden-hdr-file hdr_file]

tcplay

-j mapping

tcplay

-m mapping -d device [-e] [-f keyfile_hidden] [-k keyfile] [-s system_device] [-t] [--fde] [--use-backup] [--use-hdr-file hdr_file] [--use-hidden-hdr-file hdr_file]

tcplay

--modify -d device [-k keyfile] [--new-keyfile new_keyfile] [--new-pbkdf-prf pbkdf_hash] [-s system_device] [--fde] [--use-backup] [--use-hdr-file hdr_file] [--use-hidden-hdr-file hdr_file] [--save-hdr-backup hdr_file] [-w]

tcplay

--modify -d device [-k keyfile] --restore-from-backup-hdr [-w]

tcplay

-u mapping

tcplay

-h | -v

## DESCRIPTION
The tcplay utility provides full support for creating and opening/mapping TrueCrypt-compatible volumes. It supports the following commands, each with a set of options detailed further below:

-c, --create

Create a new encrypted TrueCrypt volume on the device specified by --device.

-h, --help

Print help message and exit.

-i, --info

Print out information about the encrypted device specified by --device.

-j mapping, --info-mapped=mapping

Print out information about the mapped tcplay volume specified by mapping. Information such as key CRC and the PBKDF2 PRF is not available via this command.

--modify

Modify the volume header. This mode allows changing passphrase, keyfiles, PBKDF2 PRF as well as restoring from a backup header.

-m mapping, --map=mapping

Map the encrypted TrueCrypt volume on the device specified by --device as a dm(4) mapping called mapping. The mapping argument should not contain any spaces or special characters.

-u mapping, --unmap=mapping

Removes (unmaps) the dm(4) mapping specified by mapping as well as any related cascade mappings. If you mapped a volume using full disk encryption and created mapping for individual partitions using kpartx(8), you must remove these prior to unmapping the volume.

-v, --version

Print version message and exit.

Options common to all commands are:

-d device, --device=device

Specifies the disk device on which the TrueCrypt volume resides/will reside. This option is mandatory for all commands.

-f keyfile_hidden, --keyfile-hidden=keyfile_hidden

Specifies a keyfile to use in addition to the passphrase when either creating a hidden volume or when protecting a hidden volume while mapping or querying the outer volume. If you only intend to map a hidden volume, the --keyfile option has to be used. This option can appear multiple times; if so, multiple keyfiles will be used. This option is not valid in the --modify mode.

-k keyfile, --keyfile=keyfile

Specifies a keyfile to use in addition to the passphrase. This option can appear multiple times; if so, multiple keyfiles will be used.

Additional options for the --create command are:

-a pbkdf_hash, --pbkdf-prf=pbkdf_hash

Specifies which hash algorithm to use for the PBKDF2 password derivation. To see which algorithms are supported, specify --pbkdf-prf=help.

-b cipher, --cipher=cipher

Specifies which cipher algorithm or cascade of ciphers to use to encrypt the new volume. To see which algorithms are supported, specify --cipher=help.

-g, --hidden

Specifies that the newly created volume will contain a hidden volume. The keyfiles applied to the passphrase for the hidden volume are those specified by --keyfile-hidden. The user will be prompted for the size of the hidden volume interactively.

-w, --weak-keys

Use urandom(4) for key material instead of a strong entropy source. This is in general a really bad idea and should only be used for testing.

-x pbkdf_hash, --pbkdf-prf-hidden=pbkdf_hash

Specifies which hash algorithm to use for the PBKDF2 password derivation for the hidden volume. Only valid in conjunction with --hidden. If no algorithm is specified, the same as for the outer volume will be used. To see which algorithms are supported, specify --pbkdf-prf-hidden=help.

-y cipher, --cipher-hidden=cipher

Specifies which cipher algorithm or cascade of ciphers to use to encrypt the hidden volume on the new TrueCrypt volume. Only valid in conjunction with --hidden. If no cipher is specified, the same as for the outer volume will be used. To see which algorithms are supported, specify --cipher-hidden=help.

-z, --insecure-erase

Skips the secure erase of the disk. Use this option carefully as it is a security risk!

Additional options for the --info, --map and --modify commands are:

-e, --protect-hidden

Specifies that an outer volume will be queried or mapped, but its reported size will be adjusted accordingly to the size of the hidden volume contained in it. Both the hidden volume and outer volume passphrase and keyfiles will be required. This option only applies to the --info and --map commands.

-s system_device, --system-encryption=system_device

This option is required if you are attempting to access a device that uses system encryption, for example an encrypted Windows system partition. It does not apply to disks using full disk encryption. The --device option will point at the actual encrypted partition, while the system_device argument will point to the parent device (i.e. underlying physical disk) of the encrypted partition.

--fde

This option is intended to be used with disks using full disk encryption (FDE). When a disk has been encrypted using TrueCrypt's FDE, the complete disk is encrypted except for the first 63 sectors. The --device option should point to the whole disk device, not to any particular partition. The resultant mapping will cover the whole disk, and will not appear as separate partitions. To access individual partitions after mapping, kpartx(8) can be used.

--use-backup

This option is intended to be used when the primary headers of a volume have been corrupted. This option will force tcplay to use the backup headers, which are located at the end of the device, to access the volume.

Additional options only for the --map command are:

-t, --allow-trim

This option enables TRIM (discard) support on the mapped volume.

Additional options only for the --modify command are:

--new-pbkdf-prf=pbkdf_hash

Specifies which hash algorithm to use for the PBKDF2 password derivation on reencrypting the volume header. If this option is not specified, the reencrypted header will use the current PRF. To see which algorithms are supported, specify --pbkdf-prf=help.

--new-keyfile=keyfile

Specifies a keyfile to use in addition to the new passphrase on reencrypting the volume header. This option can appear multiple times; if so, multiple keyfiles will be used.

--restore-from-backup-hdr

If this option is specified, neither --new-pbkdf-prf nor --new-keyfile should be specified. This option implies --use-backup. Use this option to restore the volume headers from the backup header.

Sending a SIGINFO or SIGUSR1 signal to a running tcplay process makes it print progress on slower tasks such as gathering entropy or wiping the volume.

## NOTES
TrueCrypt limits passphrases to 64 characters (including the terminating null character). To be compatible with it, tcplay does the same. All passphrases (excluding keyfiles) are trimmed to 64 characters. Similarly, keyfiles are limited to a size of 1 MB, but up to 256 keyfiles can be used.

## PLAUSIBLE DENIABILITY
tcplay offers plausible deniability. Hidden volumes are created within an outer volume. Which volume is accessed solely depends on the passphrase and keyfile(s) used. If the passphrase and keyfiles for the outer volume are specified, no information about the existance of the hidden volume is exposed. Without knowledge of the passphrase and keyfile(s) of the hidden volume its existence remains unexposed. The hidden volume can be protected when mapping the outer volume by using the --protect-hidden option and specifying the passphrase and keyfiles for both the outer and hidden volumes.

## EXAMPLES
Create a new TrueCrypt volume on /dev/vn0 using the cipher cascade of AES and Twofish and the Whirlpool hash algorithm for PBKDF2 password derivation and two keyfiles, one.key and two.key:

tcplay --create --device=/dev/vn0 --cipher=AES-256-XTS,TWOFISH-256-XTS --pbkdf-prf=whirlpool --keyfile=one.key --keyfile=two.key

Map the outer volume on the TrueCrypt volume on /dev/vn0 as truecrypt1, but protect the hidden volume, using the keyfile hidden.key, from being overwritten:

tcplay --map=truecrypt1 --device=/dev/vn0 --protect-hidden --keyfile-hidden=hidden.key

Map the hidden volume on the TrueCrypt volume on /dev/vn0 as truecrypt2, using the keyfile hidden.key:

tcplay --map=truecrypt2 --device=/dev/vn0 --keyfile=hidden.key

Map and mount the volume in the file secvol on Linux:

losetup /dev/loop1 secvol

tcplay --map=secv --device=/dev/loop1

mount /dev/mapper/secv /mnt

Similarly on DragonFly:

vnconfig vn1 secvol

tcplay --map=secv --device=/dev/vn1

mount /dev/mapper/secv /mnt

Unmapping the volume truecrypt2 on both Linux and DragonFly after unmounting:

dmsetup remove truecrypt2

Or alternatively:

tcplay --unmap=truecrypt2

A hidden volume whose existance can be plausibly denied and its outer volume can for example be created with

tcplay --create --hidden --device=/dev/loop0 --cipher=AES-256-XTS,TWOFISH-256-XTS --pbkdf-prf=whirlpool --keyfile=one.key --cipher-hidden=AES-256-XTS --pbkdf-prf-hidden=whirlpool --keyfile-hidden=hidden.key

tcplay will prompt the user for the passphrase for both the outer and hidden volume as well as the size of the hidden volume inside the outer volume. The hidden volume will be created inside the area spanned by the outer volume. The hidden volume can optionally use a different cipher and prf function as specified by the --cipher-hidden and --pbkdf-prf-hidden options. Which volume is later accessed depends only on which passphrase and keyfile(s) are being used, so that the existance of the hidden volume remains unknown without knowledge of the passphrase and keyfile it is protected by since it is located within the outer volume. To map the outer volume without potentially damaging the hidden volume, the passphrase and keyfile(s) of the hidden volume must be known and provided alongside the --protect-hidden option.

A disk encrypted using full disk encryption can be mapped using

tcplay --map=tcplay_sdb --device=/dev/sdb --fde

To access individual partitions on the now mapped disk, the following command will generate mappings for each individual partition on the encrypted disk:

kpartx --av /dev/mapper/tcplay_sdb

To restore the main volume header from the backup header, the following command can be used:

tcplay --modify --device=/dev/sdb --restore-from-backup-hdr

As with most other commands, which header is saved (used as source) depends on the passphrase and keyfiles used.

To save a backup copy of a header, the following command can be used:

tcplay --modify --device=/dev/sdb --save-hdr-backup=/tmp/sdb_backup_header.hdr

As with most other commands, which header is saved (used as source) depends on the passphrase and keyfiles used.

To restore a header from a backup header file, the following command can be used:

tcplay --modify -use-hdr-file=/tmp/sdb_backup_header.hdr

Similarly, to restore a hidden header from a backup header file:

tcplay --modify -use-hidden-hdr-file=/tmp/sdb_backup_hidden_header.hdr

Which header is used as the source of the operation will still depend on the passphrase and keyfiles used. Even if you use the --use-hidden-hdr-file option, if you specify the passphrase and keyfiles for the main header, the main header will be used instead.

## SEE ALSO
crypttab(5), cryptsetup(8), dmsetup(8), kpartx(8)

## HISTORY
The tcplay utility appeared in DragonFly 2.11.

## AUTHORS
Alex Hornung


tdbbackup

package: tdb-utils

title: tdbbackup(8)

text:
# tdbbackup(8)

## NAME
tdbbackup - tool for backing up and for validating the integrity of samba .tdb files

## SYNOPSIS
tdbbackup [-s suffix] [-v] [-h] [-n hashsize] [-l]

## DESCRIPTION
This tool is part of the samba(1) suite.

tdbbackup is a tool that may be used to backup samba .tdb files. This tool may also be used to verify the integrity of the .tdb files prior to samba startup or during normal operation. If it finds file damage and it finds a prior backup the backup file will be restored.

## OPTIONS
-h

Get help information.

-s suffix

The -s option allows the administrator to specify a file backup extension. This way it is possible to keep a history of tdb backup files by using a new suffix for each backup.

-v

The -v will check the database for damages (corrupt data) which if detected causes the backup to be restored.

-n hashsize

The -n option sets the hash size for the new backup tdb.

-l

This options disables any locking, by passing TDB_NOLOCK to tdb_open_ex(). Only use this for database files which are not used by any other process! And also only if it is otherwise not possible to open the database, e.g. databases which were created with mutex locking.

## COMMANDS
GENERAL INFORMATION

The tdbbackup utility can safely be run at any time. It was designed so that it can be used at any time to validate the integrity of tdb files, even during Samba operation. Typical usage for the command will be:

tdbbackup [-s suffix] *.tdb

Before restarting samba the following command may be run to validate .tdb files:

tdbbackup -v [-s suffix] *.tdb

Samba .tdb files are stored in various locations, be sure to run backup all .tdb file on the system. Important files includes:

•secrets.tdb - usual location is in the /usr/local/samba/private directory, or on some systems in /etc/samba.

•passdb.tdb - usual location is in the /usr/local/samba/private directory, or on some systems in /etc/samba.

•*.tdb located in the /usr/local/samba/var directory or on some systems in the /var/cache or /var/lib/samba directories.

## VERSION
This man page is correct for version 3 of the Samba suite.

## AUTHOR
The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed.

The tdbbackup man page was written by John H Terpstra.


tdbdump

title: tdbdump(8)

text:
# tdbdump(8)

## NAME
tdbdump - tool for printing the contents of a TDB file

## SYNOPSIS
tdbdump [-k keyname] [-e] [-h] {filename}

## DESCRIPTION
This tool is part of the samba(1) suite.

tdbdump is a very simple utility that 'dumps' the contents of a TDB (Trivial DataBase) file to standard output in a human-readable format.

This tool can be used when debugging problems with TDB files. It is intended for those who are somewhat familiar with Samba internals.

## OPTIONS
-h

Get help information.

-k keyname

The -k option restricts dumping to a single key, if found.

-e

The -e tries to dump out from a corrupt database. Naturally, such a dump is unreliable, at best.

## VERSION
This man page is correct for version 3 of the Samba suite.

## AUTHOR
The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed.

The tdbdump man page was written by Jelmer Vernooij.


tdbrestore

title: tdbrestore(8)

text:
# tdbrestore(8)

## NAME
tdbrestore - tool for creating a TDB file out of a tdbdump output

## SYNOPSIS
tdbrestore {tdbfilename}

## DESCRIPTION
This tool is part of the samba(1) suite.

tdbrestore is a very simple utility that 'restores' the contents of dump file into TDB (Trivial DataBase) file. The dump file is obtained from the tdbdump command.

This tool wait on the standard input for the content of the dump and will write the tdb in the tdbfilename parameter.

This tool can be used for unpacking the content of tdb as backup mean.

## VERSION
This man page is correct for version 3 of the Samba suite.

## AUTHOR
The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed. This tool was initially written by Volker Lendecke based on an idea by Simon McVittie.

The tdbrestore man page was written by Matthieu Patou.


tdbtool

title: tdbtool(8)

summary: manipulate the contents TDB files

text:
# tdbtool(8)

## NAME
tdbtool - manipulate the contents TDB files

## SYNOPSIS
tdbtool

tdbtool [-l] TDBFILE [COMMANDS...]

## DESCRIPTION
This tool is part of the samba(1) suite.

tdbtool a tool for displaying and altering the contents of Samba TDB (Trivial DataBase) files. Each of the commands listed below can be entered interactively or provided on the command line.

## OPTIONS
-l

This options disables any locking, by passing TDB_NOLOCK to tdb_open_ex(). Only use this for database files which are not used by any other process! And also only if it is otherwise not possible to open the database, e.g. databases which were created with mutex locking.

## COMMANDS
create TDBFILE

Create a new database named TDBFILE.

open TDBFILE

Open an existing database named TDBFILE.

erase

Erase the current database.

dump

Dump the current database as strings.

cdump

Dump the current database as connection records.

keys

Dump the current database keys as strings.

hexkeys

Dump the current database keys as hex values.

info

Print summary information about the current database.

insert KEY DATA

Insert a record into the current database.

move KEY TDBFILE

Move a record from the current database into TDBFILE.

store KEY DATA

Store (replace) a record in the current database.

storehex KEY DATA

Store (replace) a record in the current database where key and data are in hex format.

show KEY

Show a record by key.

delete KEY

Delete a record by key.

list

Print the current database hash table and free list.

free

Print the current database and free list.

! COMMAND

Execute the given system command.

first

Print the first record in the current database.

next

Print the next record in the current database.

check

Check the integrity of the current database.

repack

Repack a database using a temporary file to remove fragmentation.

quit

Exit tdbtool.

## CAVEATS
The contents of the Samba TDB files are private to the implementation and should not be altered with tdbtool.

## VERSION
This man page is correct for version 3.6 of the Samba suite.

## AUTHOR
The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed.


teamd

package: teamd

title: teamd(8)

summary: team network device control daemon

text:
# teamd(8)

## NAME
teamd — team network device control daemon

## SYNOPSIS
teamd -k [-p pid_file] [-g]

teamd -e [-p pid_file] [-g]

teamd -c config_text [-p pid_file] [-gdrD] [-Z address]

teamd -f config_file [-p pid_file] [-gdrD] [-Z address]

teamd -h|-V

## DESCRIPTION
teamd is a daemon to control a given team network device, during runtime, as a puppeteer controls a puppet. It uses libteam to communicate with the kernel team device instance via Netlink sockets. The behaviour depends on the selected runner and its configuration. This daemon is part of the libteam project.

## OPTIONS
-h, --help

Print help text to console and exit.

-V, --version

Print version information to console and exit.

-d, --daemonize

Daemonize after startup.

-k, --kill

Kill running daemon instance.

-e, --check

Return 0 if a daemon is already running.

-f filename, --config-file filename

Load the specified configuration file.

-c text, --config text

Use given JSON format configuration string. If this option is present then -f option will be ignored.

-p filename, --pid-file filename

Use the specified PID file.

-g, --debug

Turns on debugging messages. Repeating the option increases verbosity.

-l, --log-output

Force teamd log output to stdout, stderr or syslog.

-r, --force-recreate

Force team device recreation in case it already exists.

-o, --take-over

Take over the device if it already exists.

-N, --no-quit-destroy

This option also ensures that the team device is not removed after teamd finishes.

-t devicename, --team-dev devicename

Use the specified team device name (overrides "device" key in the configuration).

-n, --no-ports

Start without ports, even if they are listed in the configuration.

-D, --dbus-enable

Enable D-Bus interface.

-Z address, --zmq-enable address

Enable ZMQ interface. Possible address formats are "tcp://ip:port", "ipc://path" and others. Detailed description of ZMQ library is in page http://zguide.zeromq.org/page:all.

-U, --usock-enable

Enable UNIX domain socket interface. This is enabled by default.

-u, --usock-disable

Disable UNIX domain socket interface.

## SEE ALSO
teamdctl(8), teamd.conf(5), teamnl(8), bond2team(1)

## AUTHOR
Jiri Pirko is the original author and current maintainer of libteam.


teamdctl

title: teamdctl(8)

summary: team daemon control tool

text:
# teamdctl(8)

## NAME
teamdctl — team daemon control tool

## SYNOPSIS
teamdctl [options] team_device command [command_args...]

teamdctl -h

## DESCRIPTION
teamdctl is a tool that allows a user to interact with a running teamd instance. It defaults to using Unix Domain Sockets, but will fall back to using the D-Bus API, to ensure reliable operation in all environments.

## OPTIONS
-h, --help

Print help text to console and exit.

-v, --verbosity

Increase output verbosity.

-o, --oneline

Force output to one line if possible.

-D, --force-dbus

Force to use D-Bus interface.

-Z address, --force-zmq address

Force to use ZMQ interface. Possible address formats are "tcp://ip:port", "ipc://path" and others. Detailed description of ZMQ library is in page http://zguide.zeromq.org/page:all.

-U, --force-usock

Force to use UNIX domain socket interface. This is the default behavior.

## COMMAND
config dump

Dumps teamd JSON config.

config dump noports

Dumps teamd JSON configuration without "ports" section included.

config dump actual

Dumps teamd actual JSON configuration. It includes ports which are currently present.

state dump | state

Dumps teamd JSON state document.

state view

Prints out state of teamd parsed from JSON state document.

state item get state_item_path

Finds state item in JSON state document and returns its value. If PORTIFNAME in state_item_path has any sensitive character, use double quotation marks to escape it, like: ports."eth1.1".link_watches.up. To process state_item_path of 'state item set' is the same as here.

state item set state_item_path value

Finds state item in JSON state document and sets its value by value parameter. This is available only for a limited number of paths:

setup.debug_level — User can set debug level. Higher level is more verbose.

ports.PORTIFNAME.runner.aggregator.selected — This is available for lacp runner. User can manually select the aggregator.

runner.active_port — This is available for activebackup runner. User can manually select the active port.

port add portdev

Takes port device name as argument. Adds port device into team.

port remove portdev

Takes port device name as argument. Removes port device from team.

port present portdev

Takes port device name as argument. Checks if the port device is present in team.

port config update portdev portconfig-string

Takes port device name as the first argument and JSON format configuration string as the second argument. Updates port device configuration.

port config dump portdev

Takes port device name as the first argument. Dumps port device JSON configuration to standard output.

## SEE ALSO
teamd(8), teamnl(8), teamd.conf(5)

## AUTHOR
Jiri Pirko is the original author and current maintainer of libteam.


telepathy-gabble

package: telepathy-gabble

title: telepathy-gabble(8)

text:
# telepathy-gabble(8)

## NAME
telepathy-gabble - Telepathy connection manager for XMPP (Jabber)

## SYNOPSIS
/usr/libexec/telepathy-gabble

## DESCRIPTION
Gabble implements the Telepathy D-Bus specification for XMPP (Jabber), allowing Telepathy clients like empathy(1) to connect to XMPP accounts, including Google Talk.

It is a D-Bus service which runs on the session bus, and should usually be started automatically by D-Bus activation. However, it might be useful to start it manually for debugging.

## OPTIONS
There are no command-line options.

## ENVIRONMENT
GABBLE_LOGFILE=filename

If set, debug output will go to the given file rather than to stderr. If + is prepended to the filename (e.g. GABBLE_LOGFILE=+gabble.log), debug output will be appended to the file; otherwise, any existing file will be replaced.

GABBLE_DEBUG=type

May be set to "all" for full debug output, or various undocumented options (which may change from release to release) to filter the output.

WOCKY_DEBUG=type

May be set to "all" for full debug output from the Wocky XMPP library used by Gabble, or various undocumented options (which may change from release to release) to filter the output. For general Gabble debugging, "net" is recommended.

GABBLE_PERSIST=1

If set (to any value), Gabble will continue running until killed, rather than timing out if it has no open connections for a few seconds.

GABBLE_PLUGIN_DIR=directory

If set, and Gabble was compiled with plugin support, plugins will be loaded from directory rather than from the default directory.

## SEE ALSO
http://telepathy.freedesktop.org/, http://telepathy.freedesktop.org/wiki/CategoryGabble, empathy(1)


telepathy-haze

package: telepathy-haze

title: telepathy-haze(8)

text:
# telepathy-haze(8)

## NAME
telepathy-haze - Telepathy connection manager using libpurple

## SYNOPSIS
/usr/libexec/telepathy-haze

## DESCRIPTION
Haze implements the Telepathy D-Bus specification using libpurple, allowing Telepathy clients like empathy(1) to connect to any protocol supported by pidgin(1).

It is a D-Bus service which runs on the session bus, and should usually be started automatically by D-Bus activation. However, it might be useful to start it manually for debugging.

## OPTIONS
There are no command-line options.

## ENVIRONMENT
HAZE_DEBUG=type

May be set to "all" for full debug output, or various undocumented options (which may change from release to release) to filter the output.

HAZE_PERSIST=1

If set, Haze will not automatically close itself after five seconds without any connections.

HAZE_LOGFILE=filename

If set, all debugging output will be written to filename rather than to the terminal.

## SEE ALSO
http://telepathy.freedesktop.org/, empathy(1), pidgin(1)


telepathy-idle

package: telepathy-idle

title: telepathy-idle(8)

summary: Telepathy connection manager for IRC

text:
# telepathy-idle(8)

## NAME
telepathy-idle - Telepathy connection manager for IRC

## SYNOPSIS
/usr/lib/telepathy-idle

## DESCRIPTION
Idle implements the Telepathy D-Bus specification for Internet Relay Chat, allowing Telepathy clients like empathy(1) to connect to IRC servers.

It is a D-Bus service which runs on the session bus, and should usually be started automatically by D-Bus activation. However, it might be useful to start it manually for debugging.

## OPTIONS
There are no command-line options.

## ENVIRONMENT
IDLE_LOGFILE=filename

If set, debug output will go to the given file rather than to stderr. If + is prepended to the filename (e.g. IDLE_LOGFILE=+idle.log), debug output will be appended to the file; otherwise, any existing file will be replaced.

IDLE_DEBUG=type

May be set to "all" for full debug output, or various undocumented options (which may change from release to release) to filter the output.

## SEE ALSO
http://telepathy.freedesktop.org/, empathy(1)


telepathy-rakia

package: telepathy-rakia-devel

title: telepathy-rakia(8)

summary: Telepathy connection manager for SIP

text:
# telepathy-rakia(8)

## NAME
telepathy-rakia - Telepathy connection manager for SIP

## SYNOPSIS
/usr/lib/telepathy-rakia

## DESCRIPTION
telepathy-rakia implements the Telepathy D-Bus specification for the Session Initiation Protocol, allowing Telepathy clients like empathy(1) to connect to Voice over IP providers that implement SIP.

It is a D-Bus service which runs on the session bus, and should usually be started automatically by D-Bus activation. However, it might be useful to start it manually for debugging.

## OPTIONS
There are no command-line options.

## ENVIRONMENT
RAKIA_DEBUG=type

May be set to "all" for full debug output, or various undocumented options (which may change from release to release) to filter the output.

RAKIA_LOGFILE=filename

May be set to the name of a file to overwrite with log messages. The filename may be prefixed with + to append messages to an existing file instead of overwriting it.

RAKIA_PERSIST

May be set to any value to avoid telepathy-rakia's usual automatic exit when there have been no connections for a few seconds.

TPORT_LOG

May be set to any value to print all parsed SIP messages at the transport layer (this functionality is provided by the underlying Sofia-SIP library, which also offers various more specialized debugging options).

## SEE ALSO
http://telepathy.freedesktop.org/, empathy(1)


telepathy-salut

package: telepathy-salut

title: telepathy-salut(8)

text:
# telepathy-salut(8)

## NAME
telepathy-salut - Telepathy connection manager for link-local XMPP

## SYNOPSIS
/usr/lib/telepathy-salut

## DESCRIPTION
Salut implements the Telepathy D-Bus specification for link-local XMPP (XEP-0174, often called "Bonjour"), allowing Telepathy clients like empathy(1) to communicate with other implementations of link-local XMPP, such as iChat. It also extends the protocol to support multicast-based chat rooms and collaboration.

It is a D-Bus service which runs on the session bus, and should usually be started automatically by D-Bus activation. However, it might be useful to start it manually for debugging.

## OPTIONS
There are no command-line options.

## ENVIRONMENT
SALUT_LOGFILE=filename

If set, debug output will go to the given file rather than to stderr.

SALUT_DEBUG=type

May be set to "all" for full debug output, or various undocumented options (which may change from release to release) to filter the output. GIBBER_DEBUG=type May be set to "all" for full debug output from the Gibber XMPP library used by Salut, or various undocumented options (which may change from release to release) to filter the output.

## SEE ALSO
http://telepathy.freedesktop.org/, http://telepathy.freedesktop.org/wiki/CategorySalut, http://www.xmpp.org/extensions/xep-0174.html, empathy(1)


telnetd

package: telnet-server

title: telnetd(8)

summary: DARPA

text:
# telnetd(8)

## NAME
telnetd — DARPA TELNET protocol server

## SYNOPSIS
telnetd

[-BUhkln] [-D debugmode] [-S tos] [-L /bin/login] [-y]

## DESCRIPTION
The telnetd command is a server which supports the DARPA standard TELNET virtual terminal protocol. Telnetd is normally invoked by the internet server (see inetd(8)) for requests to connect to the TELNET port as indicated by the /etc/services file (see services(5)).

The telnetd command accepts the following options:

-B

Ignored.

-D debugmode

This option may be used for debugging purposes. This allows telnetd to print out debugging information to the connection, allowing the user to see what telnetd is doing. There are several possible values for debugmode: options

Prints information about the negotiation of TELNET options.

report

Prints the options information, plus some additional information about what processing is going on.

netdata

Displays the data stream received by telnetd.

ptydata

Displays data written to the pty.

exercise

Has not been implemented yet.

-h

Disables the printing of host-specific information before login has been completed.

-l

Ignored.

-n

Disable TCP keep-alives. Normally telnetd enables the TCP keep-alive mechanism to probe connections that have been idle for some period of time to determine if the client is still there, so that idle connections from machines that have crashed or can no longer be reached may be cleaned up.

-S tos

-U

This option causes telnetd to refuse connections from addresses that cannot be mapped back into a symbolic name via the getnameinfo(3) routine.

-L pathname

Specify pathname to an alternative login program.

-y

Makes telnetd not warn when a user is trying to login with cleartext passwords.

Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for a client, then creating a login process which has the slave side of the pseudo-terminal as stdin, stdout and stderr. Telnetd manipulates the master side of the pseudo-terminal, implementing the TELNET protocol and passing characters between the remote client and the login process.

When a TELNET session is started up, telnetd sends TELNET options to the client side indicating a willingness to do the following TELNET options, which are described in more detail below:

```
DO TERMINAL TYPE
DO TSPEED
DO XDISPLOC
DO NEW-ENVIRON
DO ENVIRON
WILL SUPPRESS GO AHEAD
DO ECHO
DO LINEMODE
DO NAWS
WILL STATUS
DO LFLOW
DO TIMING-MARK
```

The pseudo-terminal allocated to the client is configured to operate in “cooked” mode, and with XTABS and CRMOD enabled (see tty(4)).

Telnetd has support for enabling locally the following TELNET options:

WILL ECHO

When the LINEMODE option is enabled, a WILL ECHO or WONT ECHO will be sent to the client to indicate the current state of terminal echoing. When terminal echo is not desired, a WILL ECHO is sent to indicate that telnetd will take care of echoing any data that needs to be echoed to the terminal, and then nothing is echoed. When terminal echo is desired, a WONT ECHO is sent to indicate that telnetd will not be doing any terminal echoing, so the client should do any terminal echoing that is needed.

WILL BINARY

Indicates that the client is willing to send a 8 bits of data, rather than the normal 7 bits of the Network Virtual Terminal.

WILL SGA

Indicates that it will not be sending IAC GA, go ahead, commands.

WILL STATUS

Indicates a willingness to send the client, upon request, of the current status of all TELNET options.

WILL TIMING-MARK

Whenever a DO TIMING-MARK command is received, it is always responded to with a WILL TIMING-MARK

WILL LOGOUT

When a DO LOGOUT is received, a WILL LOGOUT is sent in response, and the TELNET session is shut down.

WILL ENCRYPT

Only sent if telnetd Kerberos is enabled, and indicates a willingness to decrypt the data stream.

Telnetd has support for enabling remotely the following TELNET options:

DO BINARY

Sent to indicate that telnetd is willing to receive an 8 bit data stream.

DO LFLOW

Requests that the client handle flow control characters remotely.

DO ECHO

This is not really supported, but is sent to identify a 4.2BSD telnet(1) client, which will improperly respond with WILL ECHO. If a WILL ECHO is received, a DONT ECHO will be sent in response.

DO TERMINAL-TYPE

Indicates a desire to be able to request the name of the type of terminal that is attached to the client side of the connection.

DO SGA

Indicates that it does not need to receive IAC GA, the go ahead command.

DO NAWS

Requests that the client inform the server when the window (display) size changes.

DO TERMINAL-SPEED

Indicates a desire to be able to request information about the speed of the serial line to which the client is attached.

DO XDISPLOC

Indicates a desire to be able to request the name of the X windows display that is associated with the telnet client.

DO NEW-ENVIRON

Indicates a desire to be able to request environment variable information, as described in RFC 1572.

DO ENVIRON

Indicates a desire to be able to request environment variable information, as described in RFC 1408.

DO LINEMODE

Only sent if telnetd is compiled with support for linemode, and requests that the client do line by line processing.

DO TIMING-MARK

Only sent if telnetd is compiled with support for both linemode and kludge linemode, and the client responded with WONT LINEMODE. If the client responds with WILL TM, the it is assumed that the client supports kludge linemode. Note that the [-k] option can be used to disable this.

## FILES
/etc/issue.net

/etc/services

## SEE ALSO
login(1), telnet(1)

## STANDARDS
RFC-854

TELNET PROTOCOL SPECIFICATION

RFC-855

TELNET OPTION SPECIFICATIONS

RFC-856

TELNET BINARY TRANSMISSION

RFC-857

TELNET ECHO OPTION

RFC-858

TELNET SUPPRESS GO AHEAD OPTION

RFC-859

TELNET STATUS OPTION

RFC-860

TELNET TIMING MARK OPTION

RFC-861

TELNET EXTENDED OPTIONS - LIST OPTION

RFC-885

TELNET END OF RECORD OPTION

RFC-1073

Telnet Window Size Option

RFC-1079

Telnet Terminal Speed Option

RFC-1091

Telnet Terminal-Type Option

RFC-1096

Telnet X Display Location Option

RFC-1123

Requirements for Internet Hosts -- Application and Support

RFC-1184

Telnet Linemode Option

RFC-1372

Telnet Remote Flow Control Option

RFC-1416

Telnet Authentication Option

RFC-1411

Telnet Authentication: Kerberos Version 4

RFC-1412

Telnet Authentication: SPX

RFC-1571

Telnet Environment Option Interoperability Issues

RFC-1572

Telnet Environment Option

## BUGS
Some TELNET commands are only partially implemented.

Because of bugs in the original 4.2 BSD telnet(1), telnetd performs some dubious protocol exchanges to try to discover if the remote client is, in fact, a 4.2 BSD telnet(1).

Binary mode has no common interpretation except between similar operating systems (Unix in this case).

The terminal type name received from the remote client is converted to lower case.

Telnetd never sends TELNET IAC GA (go ahead) commands.


fidentify

package: testdisk

title: fidentify(8)

text:
# fidentify(8)

## NAME
fidentify - Determine file type using PhotoRec database

## SYNOPSIS
fidentify [--check] [directory|file]

fidentify --version

## DESCRIPTION

fidentify identify the file type, the "extension", by using the same database than PhotoRec.

When a file or directory is specified, fidentify will output the type of file, or files under the specified directory.

If given no arguments, fidentify will output type of files under current directory.

fidentify is similar to file(1).

## OPTIONS
--check

check the file format like PhotoRec does by default

## SEE ALSO
photorec(8),testdisk(8),file(1)

## AUTHOR
PhotoRec 7.1, Data Recovery Utility, July 2019

Christophe GRENIER <grenier@cgsecurity.org>

https://www.cgsecurity.org