Rule based virtual server hangs during direct socket connections

Stephan,

your Perl based web client is most likely sending just linefeed characters (\n - hex 0a) instead of carriage return, linefeed sequences (\r\n - hex 0d,0a) as line terminators as is mandated by applicable RFCs (2616, 1945). BIG-IP HTTP parser used by the iRule engine requires lines to be terminated by carriage return, linefeed sequences. All normal web clients DoTheRightThing(tm). Also Unix/Linux bases TELNET clients by default translate \n to \r\n. The example you've refered to clearly uses only \n as line terminator:

 contact the server
if (open_TCP(F, $ARGV[0], 80) == undef) {
  print "Error connecting to server at $ARGV[0]\n";
  exit(-1);
}
 
 send the GET method with / as a parameter
print F "GET / HTTP/1.0\n\n";

Unless there is some behind-the-scenes translation, that is your problem. It can be trivially fixed by prefixing every \n with \r, like this:

 contact the server
 send the GET method with / as a parameter
print F "GET / HTTP/1.0\r\n\r\n";