ssh_config

Host *
    GSSAPIAuthentication no
    AddressFamily inet
    TCPKeepAlive yes
    ServerAliveInterval 55
    Compression yes
    #LogLevel DEBUG

    #reuse connections
    ControlMaster auto
    ControlPersist 600
    ControlPath ~/.ssh/.tmp_session/%h_%p_%r

Host ec2-*.compute.amazonaws.com
    # Note that this "%C" work on OpenSSH v6.7+, so comment out, disablle multiplexing by default.
    # This will generates a hash from the concatenation of %l%h%p%r,
    # SO it'll help if you got "ControlPath domain.blah.blah ... too long for Unix domain socket" problem.

    # Need OpenSSH   v6.7+ :  (e.g. on Ubuntu 16.04 or homebrew)
    #ControlPath ~/.ssh/.tmp_session/%C
    # For OpenSSH  < v6.7  :
    ControlMaster no

Host do.not.use.multiplexing
    ControlMaster no

Host for.x11.forwarding
    ForwardX11 yes
    ForwardX11Trusted yes

Host internal
    ProxyCommand ssh jumphost.internal -W %h:%p

Host internal2
    ProxyJump jumphost.internal # OpenSSH v7.3+ shortcut