Typing less with SSH

For me as a Linux^w user I always had to type long lines to start my SSH^w sessions. It’s no rocket science, you know, but for he who types thousands of characters each day, each character save is golden.

We usally start our SSH sessions by typing the following command string:

ssh user@domain.tld

I’ve tried to shorten this by adding the domain and its TLD^w to my hosts file with a shorter alias like

hname hostname.tld

But obviously that crashed against Apache^w Vhost^w capability, the request never make it to the other end.

I personally have SSH keys on some of my servers to avoid typing passwords, that is good to prevent against MITM^w attacks and keyloggers, but I still have to type the string mentioned lines above.

Then, with 3 lines in a SSH’s configuration file on my home directory (yes, you don’t need to alter the server’s SSH configuration file and yes, you can do that on your shared hosting’s shell account).

It’s very simple. SSH allows some user-based configuration in your ~/.ssh directory (note that ~ stands for your home directory (usually /home/yourusername) and it also provides Aliases^w capability.

The aliases can be configured in such a way that you won’t need to type neither the FQDN^w nor even type a single username EVER MORE!

Your old

ssh user@domain.tld

will be shortened to

ssh aliasname

Ok, talk is cheap, show me the code!

Creating the need files and directories

All the magic occurs on the config in your already-mentioned ~/.ssh/ directory. If you don’t have one, create it and secure it, as the following:

mkdir ~/.ssh/
chmod 700 ~/.ssh/

If the file does not exists, create it and secure it propperly, like:

touch ~/.ssh/config
chmod 600 ~/.ssh/config

Syntax model

Host [alias name]
HostName [host's fqdn]
User [username to log-in as]

Without the braces, please!

For a user called jdoe on mydomain.com being shorted md, the code would be the following:

Host md
HostName mydomain.com
User jdoe

Save the file and you can start typing less with SSH:

ssh md

And that’s IT!

Wow that’s great! What else this beauty can do?

Omnipresence

Do you have the same username in a large number of machines, like in a local network? So you have to love the * wildcard.

Host *
User jdoe

I have many names

Want to follow a naming pattern but also wants to have shorter ones? Give multiple aliases!

Host gdf gandalf
HostName gandalf.mydomain.com
User jdoe

Avoid the front door

Security through obscurity is always fun! Have your SSH aliases even in hosts with sshd running in a different port.

Host md
HostName mydomain.com
User jdoe
Port 11

Be backwards compatible

Have outdated SSH servers? I hope not! But if you do, you may also define a different protocol in a host-based manner.

Host md
HostName mydomain.com
User jdoe
Protocol 1

Handle multiple keys

You may specify the specific (what?) SSH key file for a host.

Host md
HostName mydomain.com
User jdoe
IdentityFile ~/mykey.pub

And it also works on SCP!

Oh yeah, file transfers are easier now!

scp somefile.txt md:/path/to/upload

More parameters can be found on SSH manual, page 5.

man ssh 5

Phew! That’s all folks! Hope it helps someone as much as helped me! Anyone have any neat SSH trick?