~/.ssh/config behind firewall (ssh via HTTP proxy) and faster session creation by reusing already established connection

config

# User ssh configuration file ~/.ssh/config
# Gist https://gist.github.com/terrywang/3997931
# man ssh_config for more information
# Inspired by the blog post below to fight the NSA
# https://stribika.github.io/2015/01/04/secure-secure-shell.html

# Outside of the firewall, with HTTPS proxy
# Package connect-proxy is required.

# Amazon EC2
Host *.compute.amazonaws.com
    ProxyCommand connect -H proxy.company.com:80 %h %p
    ServerAliveInterval 30

# cloud.terry.im
Host cloud.terry.im
    ProxyCommand connect -H proxy.company.com:80 %h %p
    ServerAliveInterval 30

# Digital Ocean
Host 192.241.*.*
    ProxyCommand connect -H proxy.company.com:80 %h %p
    ServerAliveInterval 30

# Inside the firewall (do not use proxy)
Host *
    ProxyCommand connect %h %p

Host *
    # key exchange algorithms
    KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
    # client authenticaiton
    # PasswordAuthentication no
    ChallengeResponseAuthentication no
    PubkeyAuthentication yes
    # host key algorithms the client wants to use in order of preference
    HostKeyAlgorithms ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-ed25519,ssh-rsa
    # symmetric ciphers in order of preference
    Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
    # Message Authentication Code algorithms in order of preference for data integrity protection
    MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com
    ServerAliveInterval 30
    # Speed up SSH session creation
    # by sharing multiple sessions over a single network connection
    # reuse already established TCP connection
    # ControlMaster auto
    # ControlPath ~/.ssh/sockets/%r@%h-%p
    # ControlPersist 600
    # Disable roaming explicitly anyway for good
    # UseRoaming no # Disable as it is by default off
    VisualHostKey yes
    # Ensure KnownHosts are unreadable if leaked
    # otherwise it is easier to know which hosts your keys have access to
    # HashKnownHosts yes
    # macOS Sierra - add passphrases to keychain
    UseKeychain yes
    # Load keys into ssh-agent
    AddKeysToAgent yes