This server (opentftpdspV1.6x) is single port TFTP Server based on Trivial File
Transfer Protocol and is normally used for PXE Boot or firmware load. It
supports advance options like tsize, blksize, block number rollover and timeout.
There is one multiport version (opentftpdmtV1.6x) also available on website. If
you do not have firewall issues, you should use that. Multiport server accepts
all requests on listening port but responds on a new port for each request, using
a separate thread. Multithreaded version runs little faster.
On contrary, this single port server responds to requests back on same
listening port. This way firewall need to be opened for one port only.
Despite using single port, it too can serve multiple clients at same time.
If you are accessing TFTP Server using NAT Gateway, Multithreaded version of this
server will not be able to send the response back. This single port version will
work quite will through NAT Gateway too.