If the listening process binds the socket to localhost, then it will only accept connections from the local computer.

Here's an example, using IO::Socket: 

#!/usr/local/bin/perl -w

use strict;

use IO::Socket;

my $sock = IO::Socket::INET->new(Listen => 1,
                                 LocalAddr => 'localhost',
                                 LocalPort => 43546,
                                 Proto => 'tcp',
                                 Reuse => 1,
                                );

my $NL = "\015\012";

while (my $client = $sock->accept()) {
    print $client "Hello.  To close connection, type quit$NL";
    while (<$client>) {
        tr/\015\012//d;
        print "Client said $_\n";
        print $client "You said $_$NL";
        last if /^quit/i;
    }
    print "Client quit.\n";
    print $client "Bye!$NL";
    close $client;
}

[download]
Start this running, then try connecting from various computers. You'll only be able to connect from the local computer, and only when connecting specifically to 'localhost'. (Exit the server with a kill signal, e.g. Ctrl-C)

In reply to Re: local socket by chipmunk
in thread local socket by Punto

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.