5.3.4. Assign Static Ports and Use IPTables Rules
5.3.4. Assign Static Ports and Use IPTables Rules All of the servers related to NIS can be assigned specific ports except for rpc.yppasswdd - the daemon that allows users to change their login passwords. Assigning ports to the other two NIS server daemons, rpc.ypxfrd and ypserv , allows for the creation of firewall rules to further protect the NIS server daemons from intruders. To do this, add the following lines to /etc/sysconfig/network : The following IPTables rules can be issued to enforce which network the server listens to for these ports: Note Refer to Chapter 7, Firewalls for more information about implementing firewalls with IPTables commands.
YPSERV_ARGS="-p 834" YPXFRD_ARGS="-p 835" iptables -A INPUT -p ALL -s! 192.168.0.0/24 --dport 834 -j DROP iptables -A INPUT -p ALL -s! 192.168.0.0/24 --dport 835 -j DROP