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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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SSHDIG(1) SSHDIG(1)
sshdig - Provide interfaces to capture system calls from a remote
host through SSH using a remote capture binary.
sshdig [ --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-capture-command-select=<capture command selection> ] [
--remote-capture-command=<capture command> ] [
--remote-priv=<privilege elevation command selection> ] [
--remote-priv-user=<privileged user name> ] [
--remote-filter=<remote capture filter> ] [
--remote-count=<number> ] [ --remote-modern-bpf ] [
--remote-io-snaplen=<snapshot length> ]
sshdig --extcap-interfaces
sshdig --extcap-interface=<interface> --extcap-dlts
sshdig --extcap-interface=<interface> --extcap-config
sshdig --extcap-interface=<interface> --fifo=<path to file or
pipe> --capture --remote-host=myremotehost --remote-port=22
--remote-username=user --remote-capture-command='sysdig
--unbuffered --write=-'
Sshdig is an extcap tool that allows one to capture system calls
over a SSH connection. You must have permission to capture system
calls on the remote system.
The feature is functionally equivalent to
$ ssh remoteuser@remotehost -p 22222 'sysdig --unbuffered -w -' > FILE &
$ stratoshark FILE
Typically sshdig is not invoked directly. Instead it can be
configured through the Stratoshark graphical user interface or its
command line. The following will start Stratoshark and start
capturing from host remotehost:
$ stratoshark '-oextcap.sshdig.remotehost:myserver.home.arpa' -i sshdig -k
Supported interfaces:
1. sshdig
--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 Stratoshark 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-capture-command-select=<capture command-selection>
The command to run on the remote system. Either sysdig for a
remote capture command using sysdig, or other, where the
remote capture command must be provided with the
--remote-capture-command option.
--remote-capture-command=<capture command>
A custom remote capture command that produces the remote
stream that is shown in Stratoshark. The command must be able
to produce a .scap stream written to STDOUT.
--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 requires a user name it may be provided
here.
--remote-filter=<capture filter>
The remote capture filter. This is passed to the remote
capture program, and must comply with its syntax rules.
--remote-count=<number>
The number of events to capture.
--remote-modern-bpf
Capture using an eBPF probe instead of the kernel module.
--remote-io-snaplen=<snapshot length>
The number of bytes to capture in each I/O event.
To see program arguments:
sshdig --help
To see program version:
sshdig --version
To see interfaces:
sshdig --extcap-interfaces
Only one interface (sshdig) is supported.
Example output
interface {value=sshdig}{display=SSH remote syscall capture}
To see interface DLTs:
sshdig --extcap-interface=sshdig --extcap-dlts
Example output
dlt {number=147}{name=sshdig}{display=Remote capture dependent DLT}
To see interface configuration options:
sshdig --extcap-interface=sshdig --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=--ssh-sha1}{display=Support SHA-1 keys (deprecated)}{type=boolflag}{tooltip=Support keys and key exchange algorithms using SHA-1 (deprecated)}{group=Authentication}
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=sysdig}{display=sysdig}
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}
{group=Capture}
arg {number=12}{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=13}{call=--log-level}{display=Set the log level}{type=selector}{tooltip=Set the log level}{required=false}{group=Debug}
value {arg=13}{value=message}{display=Message}{default=true}
value {arg=13}{value=info}{display=Info}
value {arg=13}{value=debug}{display=Debug}
value {arg=13}{value=noisy}{display=Noisy}
arg {number=14}{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:
sshdig --extcap-interface=sshdig --fifo=/tmp/ssh.scap --capture --remote-host 192.168.1.10
--remote-username user
Note
CTRL + C should be used to stop the capture in order to ensure
clean termination.
The sshdig binary can be renamed to support multiple instances.
For instance if we want sshdig to show up twice in Stratoshark
(for instance to handle multiple profiles), we can copy sshdig to
sshdig-host1 and sshdig-host2. Each binary will show up an
interface name same as the executable name. Those executables not
being "sshdig" will show up as "custom version" in the capture
source description.
stratoshark(1), tshark(1), dumpcap(1), extcap(4), tcpdump(1)
Sshdig is part of the Stratoshark distribution. The latest version
of Stratoshark can be found at https://www.wireshark.org.
HTML versions of the Stratoshark 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
man-pages@man7.org
2025-08-09 SSHDIG(1)
Pages that refer to this page: 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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