ssh.completion.bash

export COMP_WORDBREAKS=${COMP_WORDBREAKS/\:/}

_sshcomplete() {
    local CURRENT_PROMPT="${COMP_WORDS[COMP_CWORD]}"
    if [[ ${CURRENT_PROMPT} == *@*  ]] ; then
      local OPTIONS="-P ${CURRENT_PROMPT/@*/}@ -- ${CURRENT_PROMPT/*@/}"
    else
      local OPTIONS=" -- ${CURRENT_PROMPT}"
    fi


    # parse all defined hosts from .ssh/config
    if [ -r $HOME/.ssh/config ]; then
        COMPREPLY=($(compgen -W "$(grep ^Host $HOME/.ssh/config | awk '{print $2}' )" ${OPTIONS}) )
    fi

    # parse all hosts found in .ssh/known_hosts
    if [ -r $HOME/.ssh/known_hosts ]; then
        if grep -v -q -e '^ ssh-rsa' $HOME/.ssh/known_hosts ; then
            COMPREPLY=( ${COMPREPLY[@]} $(compgen -W "$( awk '{print $1}' $HOME/.ssh/known_hosts | cut -d, -f 1 | sed -e 's/\[//g' | sed -e 's/\]//g' | cut -d: -f1 | grep -v ssh-rsa)" ${OPTIONS}) )
        fi
    fi

    # parse hosts defined in /etc/hosts
    if [ -r /etc/hosts ]; then
        COMPREPLY=( ${COMPREPLY[@]} $(compgen -W "$( grep -v '^[[:space:]]*$' /etc/hosts | grep -v '^#' | awk '{print $2}' )" ${OPTIONS}) )
    fi

    return 0
}

complete -o default -o nospace -F _sshcomplete ssh

Without Username

|ruby-2.1.2| gm25795-2 in ~
○ → ssh dealestate-app1<TAB><TAB>
dealestate-app1-staging.snc1  dealestate-app1-uat.snc1      dealestate-app1.snc1

|ruby-2.1.2| gm25795-2 in ~
○ → ssh dealestate-app1

Works as expected

With Username

|ruby-2.1.2| gm25795-2 in ~
○ → ssh user@dealestate-app1<TAB>

Pressing TAB here replaces the current prompt and user input with the following

|ruby-2.1.2| gm25795-2 in ~
○ → ssh useruser@dealestate-app1

Pressing TAB a second time, replaces again with:

|ruby-2.1.2| gm25795-2 in ~
○ → ssh useruseruseruser@dealestate-app1