How can I get list of open SSH tunnels?

Solution 1:

You can use lsof:

$ lsof -i tcp | grep ^ssh
ssh       2211 lcipriani    3r  IPv4  20825      0t0  TCP lcipriani-laptop.local:49164->docsuite.cefla.com:22 (ESTABLISHED)
ssh       2223 lcipriani    3r  IPv4  21945      0t0  TCP lcipriani-laptop.local:34471->gd-b-21.vps.redomino.com:22 (ESTABLISHED)
ssh       2640 lcipriani    3r  IPv4  37488      0t0  TCP lcipriani-laptop.local:45693->makeda-xen1.redomino.com:22 (ESTABLISHED)
ssh       5279 lcipriani    3r  IPv4 212324      0t0  TCP lcipriani-laptop.local:56491->67.227.82.162:22 (ESTABLISHED)
ssh       5279 lcipriani    4u  IPv6 210281      0t0  TCP lcipriani-laptop:10000 (LISTEN)
ssh       5279 lcipriani    5u  IPv4 210282      0t0  TCP localhost.localdomain:10000 (LISTEN)

The last line represent a tunnel (look at the state LISTEN).

Solution 2:

In Ubuntu, with iptables and iptstate installed and standard ssh port:

iptstate -D 22

each line will represent open tunnel.

Solution 3:

If you're trying to find out what's using the tunnel(s) in a single ssh session, type ~# at the beginning of a line.

Solution 4:

/sbin/ip tunnel list # replacement for the deprecated iptunnel command