Alias, making quick custom commands

Recently I placed my home computer on the Internet for a remote access but also to run a personal web page. The problem I had is while I enabled ssh access using only private keys, I was still worried that I might leave a loop hole open on the system.

So here I was constantly checking the logs for any alerts to SSHD service. The command I would run is something simple, "tail /var/log/messages | grep sshd".

The results would typically something as simple as a few lines but it would be important to keep up on. Here's an example.



$ tail /var/log/messages | grep sshd
Nov 25 03:13:59 server1 sshd[927]: error: PAM: authentication error for user from 192.168.1.100
Nov 25 03:14:06 server1 sshd[927]: error: PAM: authentication error for user from 192.168.1.100
Nov 25 05:50:25 server1 sshd[1299]: error: PAM: authentication error for illegal user root from 192.168.1.100

Now this is kinda of a long command to type out each time, I was wondering if I could just type something shorter?

Here's where the alias command comes into play. From your terminal, you can type "alias" and find out what are your current alias commands. 

$ alias

g='egrep -i'

h='fc -l'

j=jobs

l='ls -l'

ll='ls -laFo'

m=more

We're now going to add our search command as listed above, but make an alias to "searchsshd". 

$ alias searchsshd='tail /var/log/messages | grep sshd'

Now, when we type "searchsshd" we get the following. 

$ tail /var/log/messages | grep sshd
Nov 25 03:13:59 server1 sshd[927]: error: PAM: authentication error for user from 192.168.1.100
Nov 25 03:14:06 server1 sshd[927]: error: PAM: authentication error for user from 192.168.1.100
Nov 25 05:50:25 server1 sshd[1299]: error: PAM: authentication error for illegal user root from 192.168.1.100

Pretty cool! 

Rob