I found this shell line over at insecure.org and decided it would be a nice exercise to do it entirely in perl. Its a little trick with netcat and grep to pull out the server header from an http request...

#!/usr/bin/perl
# What The Server Is RUNning
# get the server make (and maybe OS) by GETting
# a simple query via http...

if (!$ARGV[0]) {
  print "Usage: witsirun.pl [host] [port]\n";
} else {
  $ARGV[1] = 80 if ! $ARGV[1];
  print "Getting ";
  print `echo 'GET / HTTP/1.0\n' | netcat $ARGV[0] $ARGV[1] | grep '^S
+erver:'`;
}
[download]

Would anyone care to take a stab at a best approach to doing this? Use sockets and a while on the file handle?

Cheers!