Here is contributions that people have made for inprovments to Arla and AFS.
natkeep is written by Matthew Fredette <fredette@mit.edu>.
natkeep monitors the network, watching for connections between AFS clients and servers, and periodically transmits fake packets matching those connections. These fake packets have a junk one-byte UDP payload, but have a user-specified TTL that is supposed to be just enough to get the packet through the NAT, without reaching the AFS servers.
natkeep is available at: