NFS static ports and firewalls

NFS makes use of the portmapper to assign ports between the server and client. This makes firewall configuration rather difficult.

On Solaris and Linux nfsd is assigned to port 2049 but the supporting protocols are handled by the portmapper and thereby ports are rather unpredictable.

Linux implements the possibility to assign static ports easily to all of the NFS services which makes firewalling a lot easier.

You just edit /etc/sysconfig/nfs and adds your preferred ports:

# Port rquotad should listen on.
RQUOTAD_PORT=875
# TCP port rpc.lockd should listen on.
LOCKD_TCPPORT=32803
# UDP port rpc.lockd should listen on.
LOCKD_UDPPORT=32769
# Port rpc.mountd should listen on.
MOUNTD_PORT=892
# Port rpc.statd should listen on.
STATD_PORT=662

Then you can edit your firewall settings in /etc/sysconfig/iptables adding the static ports:

# nfsd
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 2049 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m udp -p udp --dport 2049 -j ACCEPT
# rquotad
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 875 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m udp -p udp --dport 875 -j ACCEPT
# lockd
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 32803 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m udp -p udp --dport 32769 -j ACCEPT
# mountd
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 892 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m udp -p udp --dport 892 -j ACCEPT
# statd
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 662 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m udp -p udp --dport 662 -j ACCEPT
# portmapper
-A RH-Firewall-1-INPUT -s 127.0.0.1 -p tcp --dport 111 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 111 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 111 -j ACCEPT

You can check the configuration after restarting the nfs service:

# rpcinfo -p localhost
   program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp    662  status
    100024    1   tcp    662  status
    100011    1   udp    875  rquotad
    100011    2   udp    875  rquotad
    100011    1   tcp    875  rquotad
    100011    2   tcp    875  rquotad
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100021    1   udp  32769  nlockmgr
    100021    3   udp  32769  nlockmgr
    100021    4   udp  32769  nlockmgr
    100021    1   tcp  32803  nlockmgr
    100021    3   tcp  32803  nlockmgr
    100021    4   tcp  32803  nlockmgr
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs
    100005    1   udp    892  mountd
    100005    1   tcp    892  mountd
    100005    2   udp    892  mountd
    100005    2   tcp    892  mountd
    100005    3   udp    892  mountd
    100005    3   tcp    892  mountd

Everything's fine and running on the specified ports.