Due to this I am unable to retrive file with second post.

I think you're trying to access a protected file,
you may try something like this:

( See lwpcook )

#!/usr/bin/perl
use strict;
use warnings;
use LWP::UserAgent;


my $ua = LWP::UserAgent->new;
my $req = HTTP::Request->new(GET => 'http://someip:port/');
$req->authorization_basic('Username', 'password');
print $ua->request($req)->as_string;
[download]

hth,
PooLpi