IP alias access __linux configured SSH in Mac/linux

When we log on to the server with SSH on the client, the commands we enter are often troublesome, such as "SSH root@111.111.111.111". If you want to manage multiple IPs, it's really hard to remember these IPs.        Fortunately, we can use aliases to replace these difficult to remember the IP, using a similar "SSH root@server1" this way to login to the server, is not very convenient. The following describes the configuration on Mac and Linux, respectively.
Mac: In ~/.ssh/config, configure the following:

Host Server1
HostName 111.111.111.111
User root
identitiesonly Yes

After saving, host alias access is available.

Linux: Add the above configuration to the/etc/ssh/ssh_config.