You Don't Need to Type a Lengthy SSH Command

1. With ssh we often deal with lengthy domain names and plain IP addresses. To ssh easily we usually create short aliases by adding entries to /etc/hosts. This can be done using ~/.sshconfig itself:

    Host my-server-1
       Hostname 192.168.1.10
   
    Host my-server-2
       Hostname my-lenghthy-domain-name.example.com
   

   Now,

   To access 192.168.1.10:

    ssh user@my-server-1
   

   To access my-lenghthy-domain-name.example.com:

    ssh user@my-server-2
   

2. In SSH via Jump Server in One Step I shared about ssh-ing via jump servers in one step using the -J option. This too can be configured in ~/.sshconfig.

   To access 192.168.1.10 that is accessible only through 192.168.1.2 we would do:

    ssh -J user@192.168.1.2 user@192.168.1.10
   

   With the following in ~/.sshconfig:

    Host 192.168.1.10
       ProxyJump 192.168.1.2
   

   We could just do:

    ssh user@192.168.1.10
   

3. Similarly, many other configs like username, key filename could be pushed to ~/.sshconfig:

    Host my-server
       Hostname 192.168.1.10
       ProxyJump 192.168.1.2
       User foo
       IdentityFile ~/foo.pem
   
    Host my-jump-server
       Hostname 192.168.1.2
       User bar
       IdentityFile ~/bar.pem
   

   Now just by doing ssh my-server we will have access to 192.168.1.10.

Pushing these configurations to ~/.sshconfig will be very helpful if you ssh into many machines often. We could also share this with other members of the team easily.

We could also auto-generate the configuration as part of our infrastructure automation. For example, we could make a terraform code that spawns VMs to provide this configuration as output .