Install OpenSSH 7.3 in Ubuntu 16.04

openssh-7.3.sh

# WARNING: Use this at your own risk. It will probably break your other packages and cause other havoc.
# These days you should just upgrade to Ubuntu 18.04.

$ ssh -V
OpenSSH_7.2p2 Ubuntu-4ubuntu2.1, OpenSSL 1.0.2g  1 Mar 2016

wget https://launchpadlibrarian.net/277739251/openssh-client_7.3p1-1_amd64.deb
wget https://launchpadlibrarian.net/298453050/libgssapi-krb5-2_1.14.3+dfsg-2ubuntu1_amd64.deb
wget https://launchpadlibrarian.net/298453058/libkrb5-3_1.14.3+dfsg-2ubuntu1_amd64.deb
wget https://launchpadlibrarian.net/298453060/libkrb5support0_1.14.3+dfsg-2ubuntu1_amd64.deb
sudo dpkg -i libkrb5support0_1.14.3+dfsg-2ubuntu1_amd64.deb
sudo dpkg -i libkrb5-3_1.14.3+dfsg-2ubuntu1_amd64.deb
sudo dpkg -i libgssapi-krb5-2_1.14.3+dfsg-2ubuntu1_amd64.deb
sudo dpkg -i openssh-client_7.3p1-1_amd64.deb

$ ssh -V
OpenSSH_7.3p1 Ubuntu-1, OpenSSL 1.0.2g  1 Mar 2016

@cwhsu1984 if you don't mind manually patching your bash-completion installation you can enable autocomplete yourself.

Edit the /usr/share/bash-completion/bash_completion file as sudo and add this function just before a function called _known_hosts_real():

# Helper function to locate ssh included files in configs
# This function look for the "Include" keyword in ssh config files and include
# them recursively adding each result to the config variable
_included_ssh_config_files()
{
    [[ $# -lt 1 ]] && echo "error: $FUNCNAME: missing mandatory argument CONFIG"
    local configfile i f
    configfile=$1
    local included=$( command sed -ne 's/^[[:blank:]]*[Ii][Nn][Cc][Ll][Uu][Dd][Ee][[:blank:]]\{1,\}\([^#%]*\)\(#.*\)\{0,1\}$/\1/p' "${configfile}" )
    for i in ${included[@]}; do
        # Check the origin of $configfile to complete relative included paths on included
        # files according to ssh_config(5):
        #  "[...] Files without absolute paths are assumed to be in ~/.ssh if included in a user
        #   configuration file or /etc/ssh if included from the system configuration file.[...]"
        if ! [[ "$i" =~ ^\~.*|^\/.* ]]; then
            if [[ "$configfile" =~ ^\/etc\/ssh.* ]]; then
                i="/etc/ssh/$i"
            else
                i="$HOME/.ssh/$i"
            fi
        fi
        __expand_tilde_by_ref i
        # In case the expanded variable contains multiple paths
        for f in ${i}; do
            if [ -r $f ]; then
                config+=( "$f" )
                # The Included file is processed to look for Included files in itself
                _included_ssh_config_files $f
            fi
        done
    done
} # _included_ssh_config_files()

Then add the following code:

  # "Include" keyword in ssh config files
    for i in "${config[@]}"; do
        _included_ssh_config_files "$i"
    done

Just before a line that looks like:

    # Known hosts files from configs
    if [[ ${#config[@]} -gt 0 ]]; then
        local OIFS=$IFS IFS=$'\n' j
        local -a tmpkh

Source: scop/bash-completion#70

This works and updates your ssh version, but it breaks all these packages in apt, so you won't be able to use apt to install anything else afterwards.

This works and updates your ssh version, but it breaks all these packages in apt, so you won't be able to use apt to install anything else afterwards.

+1 Exactly

why yould you break your installation if the whole point of having installed a distribution is to avoid custom installs. better build from sources and install under /usr/local/bin

This broke all the packages in apt and now I can't run krb5-user :( Somehow I can't manage to uninstall v7.4 and it exists simultaneously with 7.2