ssh-ping

#!/usr/bin/env bash

# +--------------------------------------------------------------------------------------+
# | Title        : ssh-ping                                                              |
# | Description  : Check if host is reachable using ssh_config                           |
# |                Outputs 'Reply from' when server is reachable but login failed        |
# |                Outputs 'Pong from' when server is reachable and login was successful |
# | Author       : Sven Wick <sven.wick@gmx.de>                                          |
# | Contributors : Denis Meiswinkel                                                      |
# | URL          : https://github.com/vaporup/ssh-tools                                  |
# | Based On     : https://unix.stackexchange.com/a/30146/247383                         |
# |                https://stackoverflow.com/a/33277226                                  |
# +--------------------------------------------------------------------------------------+

# trap CTRL-C and call print_statistics()
trap print_statistics SIGINT

#
# Some colors for better output
#

     RED='\033[0;91m'
   GREEN='\033[0;92m'
  YELLOW='\033[0;93m'
    BLUE='\033[0;94m'
 MAGENTA='\033[0;95m'
    CYAN='\033[0;96m'
   WHITE='\033[0;97m'
    BOLD='\033[1m'
   RESET='\033[0m'

#
# Default SSH Options
#

SSH_OPTS=(
    -o "BatchMode=yes"
    -o "CheckHostIP=no"
    -o "StrictHostKeyChecking=no"
)

#
# SSH Flags which get populated later
#

SSH_FLAGS=()

#
# Defaults
#

ping_count=0           # How many requests to do
ping_interval=1        # Seconds to wait between sending each request
connect_timeout=16     # Seconds to wait for a response
ssh_seq=1              # Request Counter
requests_transmitted=0 # Count how often we sent a request
requests_received=0    # Count how often we got an answer
requests_lost=0        # Count how often we lost an answer
quiet="no"             # Do not suppress output

#
# Usage/Help message
#

function usage() {

cat << EOF

    Usage: ${0##*/} [OPTIONS] [user@]hostname

    OPTIONS:

        -4             Use IPv4 only
        -6             Use IPv6 only
        -c count       Stop after sending <count> request packets
        -C             Connect as soon as the host responds
                       and try reconnecting after a SSH session ends (e.g. rebooting).
                       Useful also for IDRAC, IPMI, ILO devices, Switches, etc...
                       which don't have a full shell environment.
                       CTRL+C stops reconnect attempts.
        -F configfile  Specifies an alternative per-user configuration file.
                       If a configuration file is given on the command line,
                       the system-wide configuration file ( /etc/ssh/ssh_config ) will be ignored.
                       The default for the per-user configuration file is ~/.ssh/config.
        -h             Show this message
        -i interval    Wait <interval> seconds between sending each request.
                       The default is 1 second.
        -l user        Try login with <user> as username. The default is the current value of \$USER.
        -D             Print timestamp (unix time + microseconds as in gettimeofday) before each line
        -H             Print timestamp (human readable) before each line
        -W timeout     Time to wait for a response, in seconds
        -p port        Port to connect to on the remote host.
                       This can be specified on a per-host basis in the configuration file.
        -q             Quiet output.
                       Nothing is displayed except the summary lines at startup time and when finished
        -n             No colors.
                       (e.g. for black on white terminals)
        -v             Verbose output

    ENVIRONMENT_VARIABLES:

        SSH_PING_NO_COLORS    if set, no colors are shown (like -n)

        Example:      SSH_PING_NO_COLORS=true ${0##*/} -c 1 hostname

    EXIT_CODES:

        0             No requests lost
        1             More than 1 request lost
        2             All requests lost

        Example:      ${0##*/} -q -c 1 hostname >/dev/null || ...


EOF

}

if [[ -z $1 || $1 == "--help" ]]; then
    usage
    exit 1
fi

function command_exists() {

    command -v "${1}" >/dev/null 2>&1

}

function get_timestamp() {

    if [[ "${print_timestamp_human_readable}" == "yes" ]]; then
      date
    else
      if [[ "${OSTYPE}" == "linux-gnu" ]] && command_exists date; then
        date +%s.%6N
      else
        command_exists perl && perl -MTime::HiRes=time -e 'printf "%.6f", time'
      fi
    fi

}

function get_request_timestamp() {

    if [[ "${OSTYPE}" == "linux-gnu" ]] && command_exists date; then
        date +%s%3N
    else
        command_exists perl && perl -MTime::HiRes=time -e 'printf "%i", time * 1000'
    fi

}

function print_statistics() {

    [[ ${requests_transmitted} -eq 0 ]] && exit

    requests_loss=$(( 100 * requests_lost / requests_transmitted ))

    echo ""
    echo -e "${WHITE}---${RESET} ${YELLOW}${host}${RESET} ${WHITE}ping statistics${RESET} ${WHITE}---${RESET}"

    statistics_ok="${GREEN}${requests_transmitted}${RESET} ${WHITE}requests transmitted${RESET}, "
    statistics_ok+="${GREEN}${requests_received}${RESET} ${WHITE}requests received${RESET}, "
    statistics_ok+="${GREEN}${requests_loss}%${RESET} ${WHITE}request loss${RESET}"

    statistics_warn="${YELLOW}${requests_transmitted}${RESET} ${WHITE}requests transmitted${RESET}, "
    statistics_warn+="${YELLOW}${requests_received}${RESET} ${WHITE}requests received${RESET}, "
    statistics_warn+="${YELLOW}${requests_loss}%${RESET} ${WHITE}request loss${RESET}"

    statistics_crit="${RED}${requests_transmitted}${RESET} ${WHITE}requests transmitted${RESET}, "
    statistics_crit+="${RED}${requests_received}${RESET} ${WHITE}requests received${RESET}, "
    statistics_crit+="${RED}${requests_loss}%${RESET} ${WHITE}request loss${RESET}"

    [[ ${requests_loss} -eq 100 ]] &&  echo -e "${statistics_crit}" && exit 2
    [[ ${requests_loss} -gt   1 ]] &&  echo -e "${statistics_warn}" && exit 1
    [[ ${requests_loss} -eq   0 ]] &&  echo -e "${statistics_ok}"   && exit

}

#
# Command line Options
#

# shellcheck disable=SC2249
while getopts ":46c:CF:hi:l:DHp:vW:qn" opt; do
    case ${opt} in
        4 )
            SSH_FLAGS+=("-4")
        ;;
        6 )
            SSH_FLAGS+=("-6")
        ;;
        c )
            [[ ${OPTARG} =~ ^[0-9]+$ ]] && ping_count=${OPTARG}
        ;;
        C )
            connect="yes"
        ;;
        F )
            SSH_FLAGS+=("-F")
            SSH_FLAGS+=("${OPTARG}")
        ;;
        h )
            usage
            exit 1
        ;;
        i )
            ping_interval=${OPTARG}
        ;;
        l )
            SSH_FLAGS+=("-l") && SSH_FLAGS+=("${OPTARG}")
        ;;
        D )
            print_timestamp="yes"
        ;;
        H )
            print_timestamp="yes"
            print_timestamp_human_readable="yes"
        ;;
        p )
            [[ ${OPTARG} =~ ^[0-9]+$ ]] && SSH_FLAGS+=("-p") && SSH_FLAGS+=("${OPTARG}")
        ;;
        v )
            verbose="yes"
        ;;
        W )
            [[ ${OPTARG} =~ ^[0-9]+$ ]] && connect_timeout=${OPTARG}
        ;;
        q )
            quiet="yes"
        ;;
        n )
            colors="no"
        ;;
        \? )
            echo "Invalid option: ${OPTARG}" 1>&2
            usage
            exit 1
        ;;
    esac
done

shift $((OPTIND - 1))

SSH_OPTS+=( -o "ConnectTimeout=${connect_timeout}" )

#
# Getting username and host from command line without using grep and awk
#
# user@host -> user gets stored in $username
#           -> host gets stored in $host
#
# If no user@ was given on the command line
# we just store the last argument as hostname
#

if [[ $1 == *"@"* ]]; then
    host="${1##*@}"
    username="${1%%@*}"
else
    host=${1}
fi

#
# Colors are counter productive
# on black on white terminals
#

# shellcheck disable=SC2154
if [[ -n "${SSH_PING_NO_COLORS}" ]]; then

    colors="no"

fi

if [[ ${colors} == no ]]; then

    unset -v RED GREEN YELLOW BLUE MAGENTA CYAN WHITE BOLD

fi

[[ -z "${host}" ]] && { echo -e "\n  ${RED}Error: No target host given${RESET}" ; usage; exit 1; }

#
# Output header with optional debugging output
#

echo -e "${BOLD}SSHPING${RESET} ${YELLOW}${host}${RESET}"

if [[ ${verbose} == yes ]]; then
    echo -e -n "${BLUE}"
    echo "SSH_FLAGS:" "${SSH_FLAGS[@]}"
    echo "SSH_OPTS:" "${SSH_OPTS[@]}"
    echo -e -n "${RESET}"
fi

if [[ ! "${OSTYPE}" == "linux-gnu" ]]; then
  command_exists perl || echo -e "${YELLOW}WARNING:${RESET} No perl found, time measure probably fails (${WHITE}time${RESET}=${RED}0${RESET} ms)" >&2
fi

while true; do

    #
    # ping only $count times or forever if $count = 0
    #

    [[ ${ping_count} -gt 0 ]] && [[ ${ssh_seq} -gt ${ping_count} ]] && break

    #
    # used for -D and or -H option
    #

    timestamp=$( get_timestamp )

    #
    # Doing the actual request and measure its execution time
    #

    start_request=$( get_request_timestamp )

    if [[ -z "${username}" ]]; then
        if [[ "${connect}" == "yes" ]]; then
            status=$(ssh "${SSH_FLAGS[@]}" "${SSH_OPTS[@]}" "sshping@${host}" echo pong 2>&1 | grep -oE 'pong|denied|sftp')
        else
            status=$(ssh "${SSH_FLAGS[@]}" "${SSH_OPTS[@]}" "${host}" echo pong 2>&1 | grep -oE 'pong|denied|sftp')
        fi
    else
        if [[ "${connect}" == "yes" ]]; then
            status=$(ssh "${SSH_FLAGS[@]}" "${SSH_OPTS[@]}" "sshping@${host}" echo pong 2>&1 | grep -oE 'pong|denied|sftp')
        else
            status=$(ssh "${SSH_FLAGS[@]}" "${SSH_OPTS[@]}" "${username}@${host}" echo pong 2>&1 | grep -oE 'pong|denied|sftp')
        fi
    fi

    end_request=$( get_request_timestamp )
    time_request=$((end_request-start_request))

    #
    # Output "Pong"  if request succeeded by login in and echoing back our string
    # Output "Reply" if the SSH server is at least talking to us but login was denied
    #

    if [[ ${status} == pong ]]; then
        requests_received=$(( requests_received + 1 ))
        [[ ${quiet} == no ]] && [[ ${print_timestamp} == yes ]] && echo -e -n "${WHITE}[${RESET}${MAGENTA}${timestamp}${RESET}${WHITE}]${RESET} "
        [[ ${quiet} == no ]] && echo -e "${GREEN}Pong${RESET} ${WHITE}from${RESET} ${YELLOW}${host}${RESET}${WHITE}: ssh_seq${RESET}=${RED}${ssh_seq}${RESET} ${WHITE}time${RESET}=${RED}${time_request}${RESET} ms"
    elif [[ ${status} == denied || ${status} == sftp ]]; then
        requests_received=$(( requests_received + 1 ))
        [[ ${quiet} == no ]] && [[ ${print_timestamp} == yes ]] && echo -e -n "${WHITE}[${RESET}${MAGENTA}${timestamp}${RESET}${WHITE}]${RESET} "
        [[ ${quiet} == no ]] && echo -e "${CYAN}Reply${RESET} ${WHITE}from${RESET} ${YELLOW}${host}${RESET}${WHITE}: ssh_seq${RESET}=${RED}${ssh_seq}${RESET} ${WHITE}time${RESET}=${RED}${time_request}${RESET} ms"
    else
        requests_lost=$(( requests_lost + 1 ))
    fi

    requests_transmitted=${ssh_seq}
    ssh_seq=$(( ssh_seq + 1 ))

    if [[ "${connect}" == "yes" ]]; then
        if [[ -z "${username}" ]]; then
            ssh "${SSH_FLAGS[@]}" -o "BatchMode=no" "${SSH_OPTS[@]}" "${host}"
        else
            ssh "${SSH_FLAGS[@]}" -o "BatchMode=no" "${SSH_OPTS[@]}" "${username}@${host}"
        fi
        echo -e "Reconnecting... (Press CTRL+C to abort)"
    fi

    #
    # Don't sleep if we do just 1 request
    #

    [[ ${ping_count} -eq 1 ]] || sleep "${ping_interval}"

done

print_statistics