check_process_listeners.sh

#!/bin/bash -eu
#
# Authors:
#    - [email protected]
#    - [email protected]
#
# Source:
#  https://gist.github.com/dosaboy/261c52e4d820699d5834b45b5c1fe5d2
#
# Description:
#   Look for "cmd" processes and that they are listening on
#   the specified port and that they are bound to an ip address
#   that is configured on a bridge with format br<num>. This is
#   useful for debugging openstack nova-network.
#
# Requires:
#   -
#
port=${1:-53}
proto=${2:-udp}
cmd=${3:-dnsmasq}
ip_path=sos_commands/networking/ip_-o_addr
netstat_path=sos_commands/networking/netstat_-W_-neopa
ps_path=sos_commands/process/ps_alxwww

echo "Checking '${cmd}' processes listening on port $port proto $proto"

cleanup()
{
((${#ftmps[@]})) || return
rm ${ftmps[@]}
}
trap cleanup EXIT

ftmps=()
[ -r "$ip_path" ] || { ip_path=`mktemp`; ip -o addr > $ip_path; ftmps+=($ip_path); }
[ -r "$netstat_path" ] || { netstat_path=`mktemp`; netstat -W -neopa > $netstat_path; ftmps+=($netstat_path); }
[ -r "$ps_path" ] || { ps_path=`mktemp`; ps -alxwww > $ps_path; ftmps+=($ps_path); }

num_procs=`grep ${cmd} $ps_path| awk '$4=="1" {print $3}'| wc -l`

readarray -t bridge_addr<<<"`sed -r 's/.+ (br[0-9]+) .+ inet ([[:digit:]\.]+)\/[[:digit:]]+ .+/\1 \2/g;t;d' $ip_path`"
declare -A blookup=()
for ba in "${bridge_addr[@]}"; do
b=`echo $ba| awk '{print $1}'`
a=`echo $ba| awk '{print $2}'`
blookup[$a]=$b
done

checked=0
errors=0
readarray -t conns<<<"`grep ":${port} " $netstat_path| awk '{print $1, $4, $8}'| grep ":${port} " $netstat_path| awk '{print $1, $4, $8}'| sed -r "s/${proto}\s+([[:digit:]\.]+):${port}\s+([[:digit:]]+)\/${cmd}.*/\1 \2/g;t;d"`"
for uc in "${conns[@]}"; do
[ -n "$uc" ] || continue
a=`echo $uc| awk '{print $1}'`
if [ "$a" != "0.0.0.0" ]; then
pid=`echo $uc| awk '{print $2}'`
if [ "${blookup[$a]:-__null__}" = '__null__' ]; then
if `grep -q "$a/" $ip_path`; then
echo "no bridge found with address $a -  this indicates that ${cmd} pid=$pid is listening to an incorrect address"
else
echo "no interfaces found with address $a -  this indicates that ${cmd} pid=$pid is listening to an unbound address that will never receive any data"
fi
((errors+=1))
fi
fi
((checked+=1))
done
echo "${checked}/$num_procs ${cmd} checked - $errors errors found"

exit 0