SSH tricks

Check SSH configuration
sshd -t

Show active SSH connections
lsof -i -n | egrep '\<ssh\>'

Script to keep alive SSH connection with varying IP:

#!/bin/bash

if [ -z "$(ps ax | awk '{print $9}' | grep 2200:svarm:2200)" ]
then
ssh -N -f -R 2200:svarm:2200 -p 2222 mynetwork.net
fi

Establish SSH tunnel to DB on background, save its PID and kill it afterwards:

#!/bin/bash

ssh  -N -L 3333:db.myserver.com:3306 jump-host &
pid=$!
do something
kill -9 $pid