Scripts to mantain a local host list (/etc/hosts) updated with all servers IPs at the same network, using a broadcast message containg "hostname and ip" over UDP:15000.

broadcastHostname.sh

# =========================
# SUBSCRIBER
# =========================

cat << 'EOF' >/usr/local/sbin/broadcastHostnameSubscriber.sh
#!/bin/bash
export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
sleep $((RANDOM%15))
for IP_ADDRESS in $(ip address show up |grep -E 'inet [0-9]' |grep -v '127.0.0.1' |sed -r 's:(^.*inet )([0-9].*)(/.*):\2:g')
do
  echo "${IP_ADDRESS} $(hostname -s)" |socat - udp-datagram:255.255.255.255:15000,broadcast,reuseaddr
done
EOF

chmod 700 /usr/local/sbin/broadcastHostnameSubscriber.sh

cat << 'EOF' >>/etc/cron.d/broadcastHostname
* * * * * root /usr/local/sbin/broadcastHostnameSubscriber.sh
EOF

# =========================
# PUBLISHER
# =========================

cat << 'EOF' >/usr/local/sbin/broadcastHostnamePublisher.sh
#!/bin/bash
export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
while true
do
  while read -a M
  do
    eval "grep '${M[@]}' /etc/hosts" || {
      sed -r "/${M[1]}/d" -i /etc/hosts
      echo "${M[@]}" >>/etc/hosts
    }
    ps --format=pid,cmd |grep 'nc -l -u -p 15000 --recv-only' |grep -v grep |awk '{print $1}' |xargs kill
  done< <(nc -l -u -p 15000 --recv-only)
  [[ $SECONDS -gt 58 ]] && break
done
EOF

chmod 700 /usr/local/sbin/broadcastHostnamePublisher.sh

cat << 'EOF' >>/etc/cron.d/broadcastHostname
* * * * * root /usr/local/sbin/broadcastHostnamePublisher.sh
EOF