I have stumbled upon a interesting problem in our application. When testing our app in a Linux VM that is unable to get a IPv4 address, LWP fails to connect to localhost. This app has the webserver running and Firefox is able to connect to it fine.

The VM: Stock CentOS 6.4 Desktop in Virtual Box on Corporate Win 7 with the following network adapters:

• eth0: Virtual box default adapter (no changes), IPv6 address, fails to connect to the internet (or just about anywhere else)
• eth1: Virtual box host only adapter, IPv4 and IPv6 address, used to ssh into VM to upload files.

When I bring up a network that has a IPv4 connection, it magically starts working. I take it down and LWP stops working. However, Firefox happily works anyways. Then when I take down all eth interfaces, it works again.

Here is the boiled down test script:

#!perl -w
use strict;
use LWP;

my $browser = LWP::UserAgent->new();
my $response = $browser->get("http://localhost:8080/index.html");
if($response->is_success()) {
  print "Success\n";
} else {
  print "Failure\n";
}
print "Response: ".$response->as_string();
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We have had a few people look into this and it has us stumped. All the system tools for networking still work for us.