#!/bin/sh
#
# Plugin to monitor auth.log or journald for sshd server events.
#
# Require read permitions for $LOG or journald
#  (set in /etc/munin/plugin-conf.d/munin-node on debian)
#
# $Log$
# Revision 2.0  2016/11/11 15:42:00  Thomas Riccardi
# Revision 1.2  2010/03/19 15:03:00  pmoranga
# Revision 1.1  2009/04/26 23:28:00  ckujau
# Revision 1.0  2009/04/22 22:00:00  zlati
# Initial revision
#
# Parameters:
#
#       config   (required)
#       autoconf (optional - used by munin-config)
#
# Magick markers (optional):
#%# family=auto
#%# capabilities=autoconf

# config example for /etc/munin/plugin-conf.d/munin-node
#[sshd_log]
#user root
#group root
#env.logfile /var/log/messages
#env.category users
#
# config example with journald
#[sshd_log]
#group systemd-journal
#env.logfile journald
#
# config example with journald on the sshd.service unit only
#[sshd_log]
#group systemd-journal
#env.logfile journald
#env.journalctlarg --unit=sshd.service
#

LOG=${logfile:-/var/log/secure}
JOURNALCTL_ARG=${journalctlarg:-_COMM=sshd}


if [ "$1" = "autoconf" ]; then
        if [ "$LOG" = "journald" ]; then
                if journalctl --no-pager --quiet --lines=1 "$JOURNALCTL_ARG" | read -r DUMMY; then
                        echo yes
                        exit 0
                else
                        echo no
                        exit 1
                fi
        else
                if [ -r "$LOG" ]; then
                        echo yes
                        exit 0
                else
                        echo no
                        exit 1
                fi
        fi
fi

if [ "$1" = "config" ]; then

        if [ "$LOG" = "journald" ]; then
                TYPE=ABSOLUTE
        else
                TYPE=DERIVE
        fi

        echo 'graph_title SSHD login stats from' "$LOG"
        echo 'graph_args --base 1000 -l 0'
        echo 'graph_vlabel logins'
        echo 'graph_category' security

        echo 'LogPass.label Successful password logins'
        echo 'LogPass.min 0'
        echo 'LogPass.type' "$TYPE"

        echo 'LogPassPAM.label Successful login via PAM'
        echo 'LogPassPAM.min 0'
        echo 'LogPassPAM.type' "$TYPE"

        echo 'LogKey.label Successful PublicKey logins'
        echo 'LogKey.min 0'
        echo 'LogKey.type' "$TYPE"

        echo 'NoID.label No identification from user'
        echo 'NoID.min 0'
        echo 'NoID.type' "$TYPE"

        echo 'rootAttempt.label Root login attempts'
        echo 'rootAttempt.min 0'
        echo 'rootAttempt.type' "$TYPE"

        echo 'InvUsr.label Invalid user login attepmts'
        echo 'InvUsr.min 0'
        echo 'InvUsr.type' "$TYPE"

        echo 'NoRDNS.label No reverse DNS for peer'
        echo 'NoRDNS.min 0'
        echo 'NoRDNS.type' "$TYPE"

        echo 'Breakin.label Potential Breakin Attempts'
        echo 'Breakin.min 0'
        echo 'Breakin.type' "$TYPE"

        exit 0
fi

if [ "$LOG" = "journald" ]; then
        CURSOR_FILE="$MUNIN_STATEFILE"
        # read cursor
        # format: "journald-cursor <cursor>"
        CURSOR=
        if [ -f "$CURSOR_FILE" ]; then
                CURSOR=$(awk '/^journald-cursor / {print $2}' "$CURSOR_FILE")
        fi
else
        CURSOR_FILE=
fi

if [ "$LOG" = "journald" ]; then
        journalctl --no-pager --quiet --show-cursor ${CURSOR:+"--after-cursor=$CURSOR"} "$JOURNALCTL_ARG"
else
        cat "$LOG"
fi | \
    awk -v cursor_file="$CURSOR_FILE" 'BEGIN{c["LogPass"]=0;c["LogKey"]=0;c["NoID"]=0;c["rootAttempt"]=0;c["InvUsr"]=0;c["LogPassPAM"]=0;c["Breakin"]=0;c["NoRDNS"]=0; }
     /sshd\[.*Accepted password for/{c["LogPass"]++}
     /sshd\[.*Accepted publickey for/{c["LogKey"]++}
     /sshd\[.*Did not receive identification string/{c["NoID"]++}
     /sshd\[.*Failed password for root/{c["rootAttempt"]++}
     /sshd\[.*Invalid user/{c["InvUsr"]++}
     /sshd\[.*POSSIBLE BREAK-IN ATTEMPT!/{c["Breakin"]++}
     /sshd\[.*keyboard-interactive\/pam/{c["LogPassPAM"]++}
     /sshd\[.*reverse mapping checking getaddrinfo/{c["NoRDNS"]++}a
     END{if (cursor_file != "") { print "journald-cursor " $3 > cursor_file };for(i in c){print i".value " c[i]} }'