Table of Contents

SSH Tunnel

Forwarding

In this example, the remote port 3306 on the remote server will be forwarded to local port 3307 using login@remoteserver for ssh credentials. The connection is pushed in the background and the port will remain forwarded as long as this ssh connection remains active. 

ssh login@remote-server -L 3307:127.0.0.1:3306 -N &

Multiple ports can be forwarded by simply repeating the -L command: 

ssh remote-host -L 8822:REMOTE_IP_1:22 -L 9922:REMOTE_IP_2:22

Full Tunnel

SSH has a “-w” option which will set up “tun” devices on either end and transport the traffic between them. If you say “ssh -w 0:0 hostname”, it will set up a “tun0” on both ends. Then you just need to ifconfig the two tunnel endpoints. You can use the “LocalCommand” setting to do one ifconfig and the remote command to do the other, for example: 

ssh -o PermitLocalCommand=yes \
    -o LocalCommand="ifconfig tun0 192.168.0.1 netmask 255.255.255.252" \
    -w 0:0 $HOSTNAME \
    'ifconfig tun0 192.168.0.2 netmask 255.255.255.252; sleep 900000'

Note that on the server you will need to set “PermitTunnel yes” in /etc/ssh/sshd_config and restart SSH. This needs to run as root on both ends to build the tunnel interface.