tricks

Some handy tips and tricks hopefully

##SSH Helper Aliases

I log into servers often where I use a user account that is not my name e.g

ssh systemuser@54.53.52.51

Seems trivial but I have probably typed ssh systemuser@ thousands of times. The solution is to create a simple function and alias in bash

function ssh-helper {
        ssh systemuser@$1
}
​
alias sshh='ssh-helper'

You can name the alias anything you like. In this case I used sshh

Another common issue is contacting AWS EC2 instances in a VPC, they may only have a private IP and may only be accessible via some jump host. Can we connect to these more easily?

Yes

function ssh-jump-helper {
        ssh -o ProxyCommand="ssh your.jumphost.com -W %h:%p" systemuser@$1
}
​
alias sshj='ssh-jump-helper'

What is going on here? Mad hax

ProxyCommand Specifies the command to use to connect to the server.

-W Requests that standard input and output on the client be forwarded to host %h on port %p over the secure channel.

Using this technique we can connect to private RFC1918 addressed within a VPC

sshj 172.16.1.1

Its a good idea to obfuscate the port on your jump host. You can specify that in the command also using the -p option. The following code connects to the jumphost on port 4567

ssh -o ProxyCommand="ssh -p 4567 your.jumphost.com -W %h:%p" systemuser@$1