Ever wonder how to log ssh sessions? Well, there are many possibilities but what I will show you here is probably the simplest way and most important: tested.

1. Create the directory where you want to put the logs:
(I choose to make it readable only by my username)

florian@mobilebox:~$ mkdir -p /home/florian/logs/ssh/
florian@mobilebox:~$ chmod 700 /home/florian/logs/ssh/
florian@mobilebox:~$ ls -lad /home/florian/logs/ssh/
drwx------ 2 florian florian 359176 2012-02-17 08:36 /home/florian/logs/ssh/

2. Create the magic line (you cannot call it script :) and make it executable:

florian@mobilebox:~$ echo 'script -f -a -q -c "/usr/bin/ssh $*" /home/florian/logs/ssh/$(date +%Y-%m-%d-%H-%M-%S)_$1.log' >/home/florian/bin/sshlog
florian@mobilebox:~$ cat /home/florian/bin/sshlog
script -f -a -q -c "/usr/bin/ssh $*" /home/florian/logs/ssh/$(date +%Y-%m-%d-%H-%M-%S)_$1.log
florian@mobilebox:~$ chmod +x /home/florian/bin/sshlog
florian@mobilebox:~$ ls -la /home/florian/bin/sshlog
-rwxr-xr-x 1 florian florian 104 2012-02-16 12:57 /home/florian/bin/sshlog

3. Add in ~/.bashrc the following line and then logout/login to your user:

florian@mobilebox:~$ echo "alias ssh='/home/florian/bin/sshlog'" >> ~/.bashrc
florian@mobilebox:~$ grep ssh ~/.bashrc
alias ssh='/home/florian/bin/sshlog'

4. Verify the alias:

florian@mobilebox:~$ type ssh
ssh is aliased to `/home/florian/bin/sshlog'

5. Now use ssh as normal and see the results:

florian@mobilebox:~$ ls -lrt /home/florian/logs/ssh/* | tail
-rw-r--r-- 1 florian florian    916022 2012-02-16 11:20 /home/florian/logs/ssh/2012-02-14-09-41-41_core.log