In this article series, I will explain how to use a command-line terminal to connect to secure shell (SSH) servers, using the config file for quick access to frequently used servers, and setting up an SSH server on macOS, Ubuntu, or CentOS.
Table of Contents:
SSH config file makes it easier to connect to frequently used servers. Here, I start with a simple server setup and then explain how to setup proxy jumps.
SSH config file is located in home directory under “.ssh” folder:
For each server, add a block of text starting with “Host” followed by a memorable name for that server.
Add information like the address of the host on the following line with indentation:
Host favorite_ssh HostName ip_or_address_of_server User username_at_the_server
Now save the file. To connect to the sever, in a terminal window simply type ssh followed by the name you chose in the config file:
$ ssh favorite_ssh
This is equivalent of typing the following command:
$ ssh username_at_the_server@ip_or_address_of_server
You can add the identity file location to the config file as well:
Host favorite_ssh HostName ip_or_address_of_server User username_at_the_server IdentityFile ~/.ssh/my_private_key
which is equivalent of the following command:.
$ ssh username_at_the_server@ip_or_address_of_server -i ~/.ssh/my_private_key
You can add multiple servers to the config file:
Host favorite_ssh HostName ip_or_address_of_server User username_at_the_server IdentityFile ~/.ssh/my_private_key Host favorite_ssh_2 HostName ip_or_address_of_server_2 User username_at_the_server_2 IdentityFile ~/.ssh/my_private_key_3 Host favorite_ssh_3 HostName ip_or_address_of_server_3 User username_at_the_server_3 IdentityFile ~/.ssh/my_private_key_3
You can add a proxy or jump server to the config file as well and use it to connect to your “favorite_ssh”:
Host proxy_1 HostName ip_or_address_of_proxy_server User username_at_proxy_server IdentityFile ~/.ssh/proxy_server_private_key Host favorite_ssh HostName ip_or_address_of_server User username_at_the_server IdentityFile ~/.ssh/my_private_key ProxyJump proxy_1
You can also use wildcards to use a same setting for a range of IP addresses (10.0.* and 10.1.0.*) :
Host proxy_1 HostName ip_or_address_of_proxy_server User username_at_proxy_server IdentityFile ~/.ssh/proxy_server_private_key Host 10.0.* User username_at_these_servers IdentityFile ~/.ssh/my_private_key_for_all_the_servers ProxyJump proxy_1 Host 10.1.0.* ProxyJump proxy_1
Now to connect to a server with IP address of 10.0.0.1, you can use the following command:
$ ssh 10.0.0.1
Or to connect to 10.1.0.2 with a username “my_user”, you can run:
$ ssh firstname.lastname@example.org
Let me know your questions and comments in the comment section.