Allowing multicast broadcasting on a Linux machine

You must allow for multicast broadcasting to take place in order for ehcache to sync successfully between servers on a Linux® machine.

Issue the iptables –list command. If multicast broadcasting is allowed, you will see a message similar to the following:
...
ACCEPT     all  --  anywhere             anywhere            PKTTYPE = multicast
...  
If multicast broadcasting is not allowed, issue the following to allow it:
$ iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT
$ service iptables save

The command will look similar to:

./iptables -I <rule_name> <position_in_rule> -m pkttype --pkt-type multicast -j ACCEPT
for example:
iptables -I RH-Firewall-1-INPUT 26 -m pkttype --pkt-type multicast -j ACCEPT
ehcache mechanism:
- Displaying the current configuration:
   ./etc/rc.d/init.d/iptables status
      oder
   iptables -list
- Add / Grant multicast traffic:
   iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT
      oder
   iptables -A INPUT -m pkttype --pkt-type multicast -j ACCEPT
      oder
   vi /etc/sysconfig/iptables
      oder
   iptables -I RH-Firewall-1-INPUT 33 -m pkttype --pkt-type multicast -j ACCEPT
- Permanently save this firewall configuration:
   service iptables save
      oder
   ./etc/rc.d/init.d/iptables save