Lectures notes for 2010 - KTH

UDP server design
Stevens, Vol, 1, pp. 162-167 discusses how to program a UDP server
You can often determine what IP address the request was sent to (i.e., the
destination address):
• for example: thus ignoring datagrams sent to a broadcast address
You can limit a server to a given incoming IP address:
• thus limiting requests to a given interface
You can limit a server to a given foreign IP address and port:
• only accepting requests from a given foreign IP address and port #
Multiple recipients per port (for implementations with multicasting support)
• setting SO_REUSEADDR socket option ⇒ each process gets a copy
of the incoming datagram
Note: limited size input queue to each UDP port, can result in silent discards
without an ICMP message being sent back (since OS discarded, not the network!)
Maguire Simple UDP client 4: 21 of 74
maguire@kth.se 2010.03.21 Internetworking/Internetteknik