nfslock vs imaps

I had a race condition on a server that made it back into production. nfslock had grabbed port 993 before imaps could. This wasn't obvious at first from the imaps client error message: The first thing is to always check your logs. I grepped based on when I restarted the service:

# egrep "^10:" 2007-11-19.log | grep -i imap | head -1
10:06:32.88 1 IMAP failed to start listener on [123.456.78.9:993]. Error
Code=network address (port) is already in use
#

I hadn't expected another service to grab that port but there it was:

# netstat -tulpn | grep 993
tcp        0      0 0.0.0.0:993                 0.0.0.0:*
    LISTEN      5899/rpc.statd
#

man rpc.statd: "The rpc.statd server implements the NSM (Network Status Monitor) RPC protocol... used by the NFS file locking service, rpc.lockd, to implement lock recovery when the NFS server machine crashes and reboots." This server used to use NFS but doesn't anymore. I stopped the service:

service nfslock stop
chkconfig nfslock off

and made sure my last chkconfg would prevent it from coming back up:

# chkconfig --list | grep nfslock
nfslock         0:off   1:off   2:off   3:off   4:off   5:off   6:off
#

While investigating this I saw that others had seen rpc.statd running on various ports. The man page said that "rpc.statd will ask portmap(8) to assign it a port number. As of this writing, there is not a standard port number that portmap always or usually assigns. Specifying a port may be useful when implementing a firewall" (thus the -p option). I find it odd that it just happened to grab a port that my server needed.