ssh

• https://www.digitalocean.com/community/tutorials/ssh-essentials-working-with-ssh-servers-clients-and-keys

How to

• https://stackoverflow.com/questions/2419566/best-way-to-use-multiple-ssh-private-keys-on-one-client

% ssh -i <key location> login@server.example.com 

~/.ssh/config

Host myshortname realname.example.com
    HostName realname.example.com
    IdentityFile ~/.ssh/realname_rsa # private key for realname
    User remoteusername

Host myother realname2.example.org
    HostName realname2.example.org
    IdentityFile ~/.ssh/realname2_rsa  # different private key for realname2
    User remoteusername

or

Host custom-host-name
    HostName <IP Address>
    Port 22
        User <Username>
        IdentityFile ~/.ssh/<Path to the private key>
        IdentitiesOnly yes
        TCPKeepAlive yes

Keepalive

• https://unix.stackexchange.com/questions/200239/how-can-i-keep-my-ssh-sessions-from-freezing

~/.ssh/config on Client

Host *
    ServerAliveInterval 100

/etc/ssh/sshd_config on Server

TCPKeepAlive yes
...
ClientAliveInterval 60
ClientAliveCountMax 10000