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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | SEE ALSO | NOTES | AUTHORS |
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SSHDUMP(1) SSHDUMP(1)
sshdump - Provide interfaces to capture packets from a remote host
through SSH using a remote capture binary.
sshdump [ --help ] [ --version ] [ --extcap-interfaces ] [
--extcap-dlts ] [ --extcap-interface=<interface> ] [
--extcap-config ] [ --extcap-capture-filter=<capture filter> ] [
--capture ] [ --fifo=<path to file or pipe> ] [ --remote-host=<IP
address> ] [ --remote-port=<TCP port> ] [
--remote-username=<username> ] [ --remote-password=<password> ] [
--sshkey=<private key path> ] [ --sshkey-passphrase=<private key
passphrase> ] [ --proxycommand=<SSH proxy command> ] [
--remote-interface=<interface> ] [
--remote-capture-command-select=<capture command selection> ] [
--remote-capture-command=<capture command> ] [
--remote-priv=<privilege elevation command selection> ] [
--remote-priv-user=<privileged user name> ] [ --remote-noprom ] [
--remote-filter=<remote capture filter> ] [
--remote-count=<number> ]
sshdump --extcap-interfaces
sshdump --extcap-interface=<interface> --extcap-dlts
sshdump --extcap-interface=<interface> --extcap-config
sshdump --extcap-interface=<interface> --fifo=<path to file or
pipe> --capture --remote-host=myremotehost --remote-port=22
--remote-username=user --remote-interface=eth2
--remote-capture-command='tcpdump -U -i eth0 -w-'
Sshdump is an extcap tool that allows one to run a remote capture
tool over a SSH connection. The requirement is that the capture
executable must have the capabilities to capture from the wanted
interface.
The feature is functionally equivalent to run commands like
$ ssh remoteuser@remotehost -p 22222 'tcpdump -U -i IFACE -w -' > FILE &
$ wireshark FILE
$ ssh remoteuser@remotehost '/sbin/dumpcap -i IFACE -P -w - -f "not port 22"' > FILE &
$ wireshark FILE
$ ssh somehost dumpcap -P -w - -f udp | tshark -i -
Typically sshdump is not invoked directly. Instead it can be
configured through the Wireshark graphical user interface or its
command line. The following will start Wireshark and start
capturing from host remotehost:
$ wireshark '-oextcap.sshdump.remotehost:"remotehost"' -i sshdump -k
To explicitly control the remote capture command:
$ wireshark '-oextcap.sshdump.remotehost:"remotehost"' \
'-oextcap.sshdump.remotecapturecommand:"tcpdump -i eth0 -Uw- not port 22"' \
-i sshdump -k
Supported interfaces:
1. sshdump
--help
Print program arguments.
--version
Print program version.
--extcap-interfaces
List available interfaces.
--extcap-interface=<interface>
Use specified interfaces.
--extcap-dlts
List DLTs of specified interface.
--extcap-config
List configuration options of specified interface.
--extcap-capture-filter=<capture filter>
The capture filter. It corresponds to the value provided via
the tshark -f option, and the Capture Filter field next to the
interfaces list in the Wireshark interface.
--capture
Start capturing from specified interface and write raw packet
data to the location specified by --fifo.
--fifo=<path to file or pipe>
Save captured packet to file or send it through pipe.
--remote-host=<remote host>
The address of the remote host for capture.
--remote-port=<remote port>
The SSH port of the remote host.
--remote-username=<username>
The username for SSH authentication.
--remote-password=<password>
The password to use (if not ssh-agent and pubkey are used).
WARNING: the passwords are stored in plaintext and visible to
all users on this system. It is recommended to use keyfiles
with a SSH agent.
--sshkey=<SSH private key path>
The path to a private key for authentication. NOTE: Only
OPENSSH key/value pair format is supported.
--sshkey-passphrase=<SSH private key passphrase>
The passphrase for the private key for authentication.
--proxycommand=<proxy command>
The command to use as proxy for the SSH connection.
--remote-interface=<remote interface>
The remote network interface to capture from.
--remote-capture-command-select=<capture command-selection>
The selection of the build-in support for remote capture
commands. Either dumpcap for a remote capture command using
dumpcap, tcpdump for a remote capture command using tcpdump,
or other, where the remote capture command is to be given with
the --remote-capture-command option.
Note that selecting dumpcap allows for specifying multiple
capture interfaces as a whitespace separated list, while
tcpdump does not.
--remote-capture-command=<capture command>
A custom remote capture command that produces the remote
stream that is shown in Wireshark. The command must be able to
produce a PCAP stream written to STDOUT. See below for more
examples.
If using tcpdump, use the -w- option to ensure that packets
are written to standard output (stdout). Include the -U option
to write packets as soon as they are received.
When specified, this command will be used as is, options such
as the capture filter (--extcap-capture-filter) will not be
appended.
--remote-priv=<privilege elevation command selection>
The command to use to achieve privilege elevation to capture
on the remote host. Either none, sudo or doas.
--remote-priv-user=<privileged user name>
If a command is used to achieve privilege elevation to capture
on the remote host this may require a user name. If needed use
this option to give that user name.
--remote-filter=<capture filter>
The remote capture filter. It corresponds to the value
provided via the tshark -f option, and the Capture Filter
field next to the interfaces list in the Wireshark interface.
--remote-count=<number>
The number of packets to capture.
To see program arguments:
sshdump --help
To see program version:
sshdump --version
To see interfaces:
sshdump --extcap-interfaces
Only one interface (sshdump) is supported.
Example output
interface {value=sshdump}{display=SSH remote capture}
To see interface DLTs:
sshdump --extcap-interface=sshdump --extcap-dlts
Example output
dlt {number=147}{name=sshdump}{display=Remote capture dependent DLT}
To see interface configuration options:
sshdump --extcap-interface=sshdump --extcap-config
Example output
arg {number=0}{call=--remote-host}{display=Remote SSH server address}{type=string}
{tooltip=The remote SSH host. It can be both an IP address or a hostname}{required=true}{group=Server}
arg {number=1}{call=--remote-port}{display=Remote SSH server port}{type=unsigned}{default=22}
{tooltip=The remote SSH host port (1-65535)}{range=1,65535}{group=Server}
arg {number=2}{call=--remote-username}{display=Remote SSH server username}{type=string}
{tooltip=The remote SSH username. If not provided, the current user will be used}{group=Authentication}
arg {number=3}{call=--remote-password}{display=Remote SSH server password}{type=password}
{tooltip=The SSH password, used when other methods (SSH agent or key files) are unavailable.}{group=Authentication}
arg {number=4}{call=--sshkey}{display=Path to SSH private key}{type=fileselect}
{tooltip=The path on the local filesystem of the private SSH key (OpenSSH format)}{mustexist=true}{group=Authentication}
arg {number=5}{call=--sshkey-passphrase}{display=SSH key passphrase}{type=password}
{tooltip=Passphrase to unlock the SSH private key}{group=Authentication}
arg {number=6}{call=--proxycommand}{display=ProxyCommand}{type=string}
{tooltip=The command to use as proxy for the SSH connection}{group=Authentication}
arg {number=7}{call=--remote-interface}{display=Remote interface}{type=string}
{tooltip=The remote network interface used for capture}{group=Capture}
arg {number=8}{call=--remote-capture-command-select}{display=Remote capture command selection}{type=radio}
{tooltip=The remote capture command to build a command line for}{group=Capture}
value {arg=8}{value=dumpcap}{display=dumpcap}
value {arg=8}{value=tcpdump}{display=tcpdump}{default=true}
value {arg=8}{value=other}{display=Other:}
arg {number=9}{call=--remote-capture-command}{display=Remote capture command}{type=string}
{tooltip=The remote command used to capture}{group=Capture}
arg {number=10}{call=--remote-priv}{display=Gain capture privilege on the remote machine}{type=radio}
{tooltip=Optionally prepend the capture command with sudo or doas on the remote machine}{group=Capture}
value {arg=10}{value=none}{display=none}{default=true}
value {arg=10}{value=sudo}{display=sudo}
value {arg=10}{value=doas -n}{display=doas}
arg {number=11}{call=--remote-priv-user}{display=Privileged user name for sudo or doas}{type=string}
{tooltip=User name of privileged user to execute the capture command on the remote machine}{group=Capture}
arg {number=12}{call=--remote-noprom}{display=No promiscuous mode}{type=boolflag}
{tooltip=Don't use promiscuous mode on the remote machine}{group=Capture}
arg {number=13}{call=--remote-filter}{display=Remote capture filter}{type=string}
{tooltip=The remote capture filter}{default=not ((host myhost) and port 22)}{group=Capture}
arg {number=14}{call=--remote-count}{display=Packets to capture}{type=unsigned}{default=0}
{tooltip=The number of remote packets to capture. (Default: inf)}{group=Capture}
arg {number=15}{call=--log-level}{display=Set the log level}{type=selector}
{tooltip=Set the log level}{required=false}{group=Debug}
value {arg=14}{value=message}{display=Message}{default=true}
value {arg=14}{value=info}{display=Info}
value {arg=14}{value=debug}{display=Debug}
value {arg=14}{value=noisy}{display=Noisy}
arg {number=16}{call=--log-file}{display=Use a file for logging}{type=fileselect}
{tooltip=Set a file where log messages are written}{required=false}{group=Debug}
To capture:
sshdump --extcap-interface=sshdump --fifo=/tmp/ssh.pcap --capture --remote-host 192.168.1.10
--remote-username user --remote-filter "not port 22"
To use different capture binaries:
sshdump --extcap-interface=sshdump --fifo=/tmp/ssh.pcap --capture --remote-host 192.168.1.10
--remote-username user --remote-priv sudo --remote-capture-command-select tcpdump
--remote-interface eth0 --remote-noprom
sshdump --extcap-interface=sshdump --fifo=/tmp/ssh.pcap --capture --remote-host 192.168.1.10
--remote-capture-command='dumpcap -i eth0 -P -w -'
sshdump --extcap-interface=sshdump --fifo=/tmp/ssh.pcap --capture --remote-host 192.168.1.10
--remote-capture-command='sudo tcpdump -i eth0 -U -w -'
Note
To stop capturing CTRL+C/kill/terminate the application.
The sshdump binary can be renamed to support multiple instances.
For instance if we want sshdump to show up twice in wireshark (for
instance to handle multiple profiles), we can copy sshdump to
sshdump-host1 and sshdump-host2. Each binary will show up an
interface name same as the executable name. Those executables not
being "sshdump" will show up as "custom version" in the interface
description.
wireshark(1), tshark(1), dumpcap(1), extcap(4), tcpdump(1)
Sshdump is part of the Wireshark distribution. The latest version
of Wireshark can be found at https://www.wireshark.org.
HTML versions of the Wireshark project man pages are available at
https://www.wireshark.org/docs/man-pages.
Original Author
Dario Lombardo <lomato[AT]gmail.com>.SH COLOPHON This page is part
of the wireshark (Interactively dump and analyze network traffic)
project. Information about the project can be found at
⟨https://www.wireshark.org/⟩. If you have a bug report for this
manual page, see
⟨https://gitlab.com/wireshark/wireshark/-/issues⟩. This page was
obtained from the project's upstream Git repository
⟨https://gitlab.com/wireshark/wireshark.git⟩ on 2025-08-11. (At
that time, the date of the most recent commit that was found in
the repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
2025-03-07 SSHDUMP(1)
Pages that refer to this page: ciscodump(1), extcap(4)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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