SSH to a host through multiple jump hosts. [Linux]

It is really frustrating to type credentials when connecting to a particular host through multiple jump hosts.

Is there a way to make things easier? Luckily YES! Follow these steps to make you life easier.

For explanation purpose I will use the following example. Here, we are trying to SSH to Host-C via Host-A and Host-B. You can extend this method to any number of Hosts.

[Your Computer]<—>[Host-A] <—> [Host-B] <—> [Host-C]

[1] First of all, create this file if not exists ~/.ssh/config

Then open that file using your favorite text editor. And type following entries and save it.

Host host-a
   User username1
   Hostname hosta.domain

Host host-b
   User username2
   Hostname hostb.domain
   Port 22
   ProxyCommand ssh -q -W %h:$p host-a

Host host-c
   User username3
   Hostname hostc.domain
   Port 22
   ProxyCommand ssh -q -W %h:$p host-b

[2] Saving credentials.

Open the terminal in ~/.ssh/ directory. Here we have 3 hosts; therefore, first we will create 3 rsa keys using this command.

ssh-keygen -t rsa -N "" -f hosta.key
ssh-keygen -t rsa -N "" -f hostb.key
ssh-keygen -t rsa -N "" -f hostc.key

Now we will save the credentials for each host. Execute the following command with argument as the host name and enter the password. Repeat for all hosts.

ssh-copy-id host-a
ssh-copy-id host-b
ssh-copy-id host-c

[3] Test the SSH. Now you can ssh to any host quickly using a single ssh command.

ssh host-c