Hi

for curiosity's sake am trying to implement a very simple DHCP-server in Perl but unfortunately I am having problems...

All the server is supposed to do is to assign an IP, a subnet-mask and a DNS-server to a client in a network that only consists of two machines (my laptop as server and a blueray player as client).

The only example for a dhcp-server I could find was part of the Net::DHCP::Packet distribution, so I tried to make that work (it does not as it is) and here is my code: 

use strict;

use IO::Socket;
use Net::DHCP::Packet;
use Net::DHCP::Constants;

my $server_ip = "10.10.10.1";
my $client_ip = "10.10.10.10";
my $subnet_mask = "255.255.255.0";

my $socket_in = IO::Socket::INET->new(
                                        LocalPort => 67,
                                        LocalAddr => "255.255.255.255"
+,
                                        Proto    => 'udp') or die $@;

while(1) {
  my $buf;
  $socket_in->recv($buf,4096);
  my $packet = new Net::DHCP::Packet($buf);

  my $messagetype = $packet->getOptionValue(DHO_DHCP_MESSAGE_TYPE());

  if ($messagetype eq DHCPDISCOVER()) {
                  send_offer($packet);
  } elsif ($messagetype eq DHCPREQUEST()) {
                  send_ack($packet);
  }
}

sub send_offer {
  my($request)=@_;

  my $socket_out = IO::Socket::INET->new(
                                          PeerPort => 68,
                                          PeerAddr => "255.255.255.255
+",
                                          LocalAddr => "$server_ip:67"
+,
                                          Broadcast => 1,
                                          Proto    => 'udp') or die $@
+;

  my $offer = new Net::DHCP::Packet(
                                     Op => BOOTREPLY(),
                                     Xid => $request->xid(),
                                     Flags => $request->flags(),
                                     Ciaddr => $request->ciaddr(),
                                     Yiaddr => $client_ip,
                                     Siaddr => $server_ip,
                                     Giaddr => $request->giaddr(),
                                     Chaddr => $request->chaddr(),
                                     DHO_DHCP_MESSAGE_TYPE() => DHCPOF
+FER(),
                                   );

  $offer->addOptionValue(DHO_SUBNET_MASK(), $subnet_mask);
  $offer->addOptionValue(DHO_NAME_SERVERS, $server_ip);

  $socket_out->send($offer->serialize()) or die $!;
  print STDERR "sent offer\n";
}

sub send_ack {
 print STDERR "send ack\n";
}

[download]
The problem that I have here is that while I can see in wireshark the dhcp-offers going out (and they look ok) the client ignores them and just keeps sending discoveries.

I believe the reason for that is that the outgoing ethernet-frames do not use the client's ethernet-address as destination but use ff:ff:ff:ff:ff:ff.

So how can I fix that or what else may I be doing wrong?

If anybody knows of a working DHCP server implementation in Perl I would be intererested to hear about it as to my surprice I could not find any.

Many thanks!

In reply to simple DHCP server in Perl by morgon

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.