#!/bin/sh
#
# Simple SFTP plugin for Nagios
# Written by Steven R. Gould (steven.gould@stevengould.org)
# Last Modified: 02-22-2011
#
# Usage: ./check_sftp_avail [ -p <port> ] -H <host>
#
# Description:
#
# This plugin will attempt to get a login prompt via sftp. Unlike the more
# complete check_sftp plugin it does not require a user name and password and
# therefore does not verify login capability. This plugin is intended to be
# used in an environment where protecting login credentials and/or keeping up
# with frequently changing passwords can become an administrative headache. As
# a result check_sftp_avail merely checks whether the sftp service is running
# and that a login prompt is obtainable remotely.
#
# Another difference between check_sftp_avail and check_sftp is that
# check_sftp_avail is completely standalone and does not require the
# installation of any other dependencies.
#
# Output:
#
# If the sftp service is running and a login prompt is obtainable,
# check_sftp_avail returns an OK state with the message, "OK: service
# available".
#
# If the sftp service is running, but the host key validation fails to
# authenticate the server, then check_sftp_avail returns a state of "WARNING"
# with the message, "WARNING: Host key verification failed - unable to
# authenticate server".
#
# If the connection is refused or cannot be made then check_sftp_avail returns
# a state of "CRITICAL" and the message "CRITICAL: service unavailable".
#
# Finally, if invalid arguments are passed in the usage information is displayed
# and a status of "UNKNOWN" is returned.
#
# Notes:
#
# If you use this plugin make sure to keep the following in mind:
#
#    1.  If you experience a status of "WARNING" and are not sure why, ensure
#        that the user account under which nagios runs - usually nagios - has
#        attempted to connect to the sftp server and accepted the server
#        certificate.
#
# Examples:
#
# Check for sftp service availability on host myhost and port 115 (the default
# for sftp):
#
#   check_sftp_avail -H myhost
#
# Check for sftp service availability on host myotherhost and port 54321 (a
# custom port):
#
#   check_sftp_avail -p 54321 -H myotherhost
#

# Paths to commands used in this script.  These
# may have to be modified to match your system setup.

SFTP="/usr/bin/sftp"
RM="/bin/rm"

PROGNAME=`/usr/bin/basename $0`
PROGPATH=`echo $0 | sed -e 's,[\\/][^\\/][^\\/]*$,,'`
REVISION="1.0.0"

. $PROGPATH/utils.sh

print_usage() {
    echo "Usage: $PROGNAME [ -p port ] -H host"
    echo "Usage: $PROGNAME --help"
    echo "Usage: $PROGNAME --version"
}

print_help() {
    print_revision $PROGNAME $REVISION
    echo ""
    print_usage
    echo ""
    echo "sftp service availability plugin for Nagios"
    echo ""
    support
}

# Make sure the correct number of command line
# arguments have been supplied

if [ $# -lt 1 ]; then
    print_usage
    exit $STATE_UNKNOWN
fi

port=115  # Default for sftp
exitstatus=$STATE_WARNING #default
while test -n "$1"; do
    case "$1" in
        --help)
            print_help
            exit $STATE_OK
            ;;
        -h)
            print_help
            exit $STATE_OK
            ;;
        --version)
            print_revision $PROGNAME $REVISION
            exit $STATE_OK
            ;;
        -V)
            print_revision $PROGNAME $REVISION
            exit $STATE_OK
            ;;
        --hostname)
            box=$2
	    shift
            ;;
        -H)
            box=$2
	    shift
            ;;
        --port)
            port=$2
	    shift
            ;;
        -p)
            port=$2
	    shift
            ;;
        *)
            echo "Unknown argument: $1"
            print_usage
            exit $STATE_UNKNOWN
            ;;
    esac
    shift
done

# Make sure a hostname and port have been specified
if [ -z "$box" -o -z "$port" ]; then
    print_usage
    exit $STATE_UNKNOWN
fi

tempfile=/tmp/check_sftp-$box.tmp
exitstatus=$STATE_UNKNOWN

$SFTP -b - $box &>$tempfile <<EOF




EOF

if [ ! -e "$tempfile" ]; then
        stdio="No sftp output found" && $RM -f $tempfile && echo $stdio && exit $STATE_UNKNOWN;
fi

status=`tail -2 $tempfile`


if [ "`grep -c 'Permission denied' $tempfile`" == "1" ]; then
    exit=$STATE_OK && stdio="OK: service available"
elif [ "`grep -c 'Host key verification failed' $tempfile`" == "1" ]; then
    exit=$STATE_WARNING && stdio="WARNING: Host key verification failed - unable to authenticate server"
else
    exit=$STATE_CRITICAL && stdio="CRITICAL: service unavailable"
fi

$RM -f $tempfile
echo $stdio
exit $exit