Multistage ssh

In some circumstances, it was necessary to use multistage SSH.
(It is bad that "ssh port 22 Operation timed out" comes out almost on AWS.)

Preparation

• Create server1's private key.
• Create server2's private key.

Update config

Edit ssh config file.

vim ~/.ssh/config

Add the following parameters.

Host preserver
  HostName server2.com
  ForwardAgent yes
  User server2user-name 
  IdentityFile ~/.ssh/server2key
  ProxyCommand ssh -l server1user-name -i ~/.ssh/server1key -p port-number server1.com -W %h:%p

Command

ssh-add ~/.ssh/server2key
ssh preserver

Enjoy!