Print incoming UDP messages as hex dump or plain text on the command line with the free Swiss File Knife for Windows, Mac OS X and Linux.

sfk udpdump [options] [group] port

create human-readable hexdump of UDP socket input,
for debugging of UDP network applications.

options
   -showle  highlights line ending characters CR and LF.
            you may also add "le" to the command name.
   -wide    dumps 32 input bytes per line.
   -lean    dumps 16 input bytes per line.
   -post    reduced format e.g. for forum posts
   -min     minimal format with alnum only text
   -echo    echo received packets back to sender.
   -stop    or stop=n stops after n received packages.
            with command chaining, default is -stop=1.
   -sep[arator] prints detailed separator between packages
            with message number, source IP and time.
   -pure    lists flat hex characters:
            53464B2D544553540D0A
   -hexsrc  lists hex comma separated values:
            0x53,0x46,0x4B,0x2D,0x54,0x45,0x53,0x54,0x0D,0x0A,
   -decsrc  lists decimal comma separated values:
            83,70,75,45,84,69,83,84,13,10,
   -maxdump=n   dump only first n bytes of incoming data.
   -flat        no hexdump, print characters as they come.
   -nohead      does not show the "received n bytes" message.
   -text        just print text, same as -flat -nohead.
                use -sep to show a header per message.
   -tofile x    write output to file x.

message filtering
   show only messages ...
   -from "s1,s2"  from IPs containing text s1 or s2.
                  note that packages from the same
                  machine may use an IP 127.0.0.1
   -from "s1 s2"  same as -from "s1,s2"
   -notfrom "s"   not from IP containing text s,
                  with ".10"  matching .10 and .100
                  but  ".10/" matching only .10
   -size n        with this size
   -minsize n     larger  or equal to n
   -maxsize n     smaller or equal to n
   -data foo      containing text "foo"
   -data 0xa0a1   containing binary data 0xa0a1

experimental multicast receive
  if a multicast group IP address is given, like
     sfk udpdump 224.0.0.123 5000
  then udpdump tries to print incoming multicast messages.
  this may or may not work depending on the OS, network
  interface, router and firewall settings, user rights and
  other programs running in parallel.

special protocol support
  sfk udpdump -bon   - print bonjour messages
  sfk udpdump -knx   - print knx messages (sfk help knx)

see also
  sfk udpsend  - send UDP packets.
  sfk hexdump  - for further format options.

examples
  sfk udpdump 5000
     waits on port 5000 for incoming udp packages.
  sfk udpdump 5000 -from .10
     show only packages from ip's containing .10
     like 192.168.100.1 or 192.168.1.100
  sfk udpdump 5000 -from ".100/,.101/,.102/"
     show only from ip's ending .100, .101 or .102
     e.g. 192.168.1.100 but not 192.168.100.1