Creating a UDP server using IO::Socket::INET without specifying a port

Question

I am trying to create a UDP server using perl IO::Socket::INET.

I am facing difficulty with using the following parameters:

• LocalHost => "0.0.0.0"
• LocalPort => 0

What I am trying to achieve is to:

• Listen on all NICs, hence the use of 0.0.0.0
• Have the OS pick a port, hence the use of 0 as the LocalPort

Using the parameters above with TCP, works just fine. When using those parameters for UDP, it doesn't work.

What I found to work with UDP, was specifying a LocalPort to something fixed and not specifying LocalHost at all, however this is not what I need.

The perl code I have is as follows:

my $sock = new IO::Socket::INET(
              LocalHost => "0.0.0.0",
              LocalPort => 0,
              Proto => 'udp') or die "failed $@";

What I use to assess if I achieved what I need or not is by checking the output of lsof -p <pid>. The following table summarizes what I am seeing in my trials:

Protocol	LocalHost	LocalPort	sockport() output	lsof -p output
TCP	0.0.0.0	0	48589	TCP *:48589 (LISTEN)
UDP	0.0.0.0	0	0	protocol: UDP
UDP	Not specified	50001	50001	UDP *:50001
UDP	output of hostname()	0	58066	UDP hostname:58066
UDP	output of hostname()	50001	50001	UDP hostname:50001

The TCP trial in the first row's is what I am trying to achieve but for UDP and I am unable to.