16 Jan 2020
After setup NFS server, you try to use showmount command to list out shared entries in server, but you get below error:
[root@client ~]# showmount -e server
clnt_create: RPC: Port mapper failure - Timed out
Then you checked firewall setting, port 111(rpcbind) and 2049(nfs) TCP are open. What you don’t know is showmount use UDP by default. So, if you want to use showmount, please open 111/udp also.
Or you can just use
# mount -t nfs4 / /mnt
That’s because NFS4 doesn’t use rpcbind, so 111/udp isn’t used in that case.