How can I configure a system as an NFS server which sits behind a firewall with NFS clients outside of the firewall?
http://kbase.redhat.com/faq/FAQ_85_5928.shtm
Resolution:
Release Found: Red Hat Enterprise Linux 4
Symptom:
NFS relies on portmap to assign the ports on which it will listen. One side effect of this is that the ports are randomly assigned, so each time NFS is restarted the ports will change. This can make it difficult to run an NFS server behind a firewall which only allows access to specific ports on the system.
Solution:
The first step is to assign a permanent port number to each of the NFS services (rquotad, mountd, statd, and lockd). While they can use any unused ports greater than 1024, it is recommended that you first consult the file /etc/services to find a valid unused port range. The following examples use the range 10000-10005.
The majority of the ports are configured through the file /etc/sysconfig/nfs. You will need to create this file if it does not exist. It should look similar to the following example:
# NFS port numbers STATD_PORT=10002 STATD_OUTGOING_PORT=10003 MOUNTD_PORT=10004 RQUOTAD_PORT=10005
The lockd service is configured differently from the others because it is compiled as a kernel module. To set the port which lockd uses, add these options in the /etc/sysconfig/nfs file:
LOCKD_UDPPORT=30001 LOCKD_TCPPORT=30001
where “30001” can be replaced with any port that is available and can be assigned for use.
After these configuration changes, you can view the port assignments with the command rpcinfo -p <hostname>
# rpcinfo -p localhost
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100021 1 udp 10001 nlockmgr
100021 3 udp 10001 nlockmgr
100021 4 udp 10001 nlockmgr
100021 1 tcp 10000 nlockmgr
100021 3 tcp 10000 nlockmgr
100021 4 tcp 10000 nlockmgr
100024 1 udp 10002 status
100024 1 tcp 10002 status
100011 1 udp 10005 rquotad
100011 2 udp 10005 rquotad
100011 1 tcp 10005 rquotad
100011 2 tcp 10005 rquotad
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100005 1 udp 10004 mountd
100005 1 tcp 10004 mountd
100005 2 udp 10004 mountd
100005 2 tcp 10004 mountd
100005 3 udp 10004 mountd
100005 3 tcp 10004 mountd
At this point, the ports will remain the same when NFS is restarted. The following is a list of ports which need to be opened on the firewall:
- 111: portmap (tcp/udp)
- 2049: nfs (tcp/udp)
- 10000: example lockd (tcp)
- 10001: example lockd (udp)
- 10002: example statd/status (tcp/udp)
- 10003: example statd/status outgoing (tcp/udp)
- 10004: example mountd (tcp/udp)
- 10005: example rquotad (tcp/udp)
You can now open these ports on the firewall to allow remote clients to mount a share on the server. If you are using iptables, the following commands can be used to add inbound/outbound rules to allow access to these ports. Note that this is only an example, as your specific firewall rules may differ:
# iptables -A INPUT -p tcp -m tcp --dport 111 -j ACCEPT # iptables -A INPUT -p udp -m udp --dport 111 -j ACCEPT # iptables -A INPUT -p tcp -m tcp --dport 2049 -j ACCEPT # iptables -A INPUT -p udp -m udp --dport 2049 -j ACCEPT # iptables -A INPUT -p tcp -m tcp --dport 10000 -j ACCEPT # iptables -A INPUT -p udp -m udp --dport 10001 -j ACCEPT # iptables -A INPUT -p tcp -m tcp --dport 10002:10005 -j ACCEPT # iptables -A INPUT -p udp -m udp --dport 10002:10005 -j ACCEPT # iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT # iptables -A INPUT -j REJECT --reject-with icmp-port-unreachable # iptables -A OUTPUT -p tcp -m tcp --dport 111 -j ACCEPT # iptables -A OUTPUT -p udp -m udp --dport 111 -j ACCEPT # iptables -A OUTPUT -p tcp -m tcp --dport 2049 -j ACCEPT # iptables -A OUTPUT -p udp -m udp --dport 2049 -j ACCEPT # iptables -A OUTPUT -p tcp -m tcp --dport 10000 -j ACCEPT # iptables -A OUTPUT -p udp -m udp --dport 10001 -j ACCEPT # iptables -A OUTPUT -p tcp -m tcp --dport 10002:10005 -j ACCEPT # iptables -A OUTPUT -p udp -m udp --dport 10002:10005 -j ACCEPT # iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT # iptables -A OUTPUT -j REJECT --reject-with icmp-port-unreachable
Note: Mount requests without the specific options for tcp will default to udp.