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 .

Originally published at https://arunvelsriram.dev.

Open Source | DevOps | Infrastructure | Backend | Ployglot Programmer

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