Portmapper is a UDP application, and is subject to the UDP access controls previously discussed. These clients use the well known port 2049 for NFS traffic. For rpcproxy to work with these clients in UDP , do not code udprpc on the permit line for port 2049. Most systems limit the maximum number of open files for a single process. Usually there is a soft and a hard maximum value.
Some systems allow the soft maximum to be increased up to the value of the hard limit.
The rpcproxy automatically increases the maximum number of open files to the systems hard limit. This is done for the following reasons. The rpcproxy runs as a single process and uses multiple file descriptors for each transaction. Each rpc transaction requires two sockets, one for each side of the firewall. Increasing the max open limit prevents rpcproxy from aborting a transactions due to a resource shortage.