sshdig(1)

# sshdig(1) Manual Page

## NAME

sshdig - Provide interfaces to capture system calls from a remote host through SSH using a remote capture binary.

## SYNOPSIS

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=-'

## DESCRIPTION

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

## OPTIONS

--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.

## EXAMPLES

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.

## SEE ALSO

stratoshark(1), strato(1), dumpcap(1), extcap(4)

## NOTES

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.

## AUTHORS

Original Author

Dario Lombardo <lomato[AT]gmail.com>