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 .

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