DHCP relay

[Steffen Beyer]

Hi,

I'm trying to set up relaying on a 3.1 box and stuck with a problem:
the client request gets forwarded to the server but the answer is dropped.

Could there be a problem for dhcrelay with the different IPs for one host?

Steffen


Details:

(192.168.1.1)
DHCP server
(192.168.2.1)
|
(192.168.2.2)
DHCP relay
(192.168.3.1)
|
(192.168.3.2)
DHCP client

relay# dhcrelay -d -i $client 192.168.2.1 # 192.168.1.1 also fails
Internet Software Consortium DHCP Relay Agent 2.0pl5-OpenBSD
Copyright 1997, 1998, 1999 The Internet Software Consortium.
All rights reserved.

Please contribute if you find this software useful.
For info, please visit http://www.isc.org/dhcp-contrib.html

Listening on BPF/de0/00:e0:29:14:5f:d7
Sending on BPF/de0/00:e0:29:14:5f:d7
Sending on Socket/fallback/fallback-net

relay# tcpdump -n -e -ttt -i $client
tcpdump: listening on de0
Sep 21 10:05:02.883927 0:4:75:62:b4:69 ff:ff:ff:ff:ff:ff 0800 590:
0.0.0.0.68 > 255.255.255.255.67: xid:0x84b4dcbe [|bootp]

relay# tcpdump -n -e -ttt -i $server
Sep 21 10:05:02.884315 0:10:f3:0:72:fc 0:4:e2:22:d4:ea 0800 590:
192.168.2.2.67 > 192.168.2.1.67: (request) xid:0x84b4dcbe
G:192.168.3.1 ether 0:4:75:62:b4:69 [|bootp]

Sep 21 10:05:02.982752 0:4:e2:22:d4:ea 0:10:f3:0:72:fc 0800 343:
192.168.2.1.67 > 192.168.3.1.67: (reply) xid:0x84b4dcbe Y:192.168.3.2
S:192.168.1.1 G:192.168.3.1 ether 0:4:75:62:b4:69 [|bootp] (DF)

server# tail syslog
Sep 21 10:05:02 a-traxx dhcpd: DHCPDISCOVER from 00:04:75:62:b4:69 via
192.168.3.1
Sep 21 10:05:02 a-traxx dhcpd: DHCPOFFER on 192.168.3.2 to
00:04:75:62:b4:69 via 192.168.3.1

[Michael Erdely]

Steffen,

I found that you have to specify both interfaces.

Take my example: I have two networks, one for wireless and one for my
internal, wired machines. My firewall has 3 interfaces: one is for the
internet, one if for my wired connections (fxp0 = 192.168.25.1) and one
is a cross-over cable to my Wireless AP (fxp2 = 172.16.25.1).

Hanging off of fxp0 is another OpenBSD server (192.168.25.10) running
DHCP. It has scopes defined for my private network (192.168.25.0/24)
and my wireless network (172.16.25.0/24).

On my firewall, instead of running and maintaining a second DHCP server
for the wireless network, I'm using dhcrelay.
Here is my command to start the process:
dhcrelay -q -i fxp0 -i fxp2 192.168.25.10

Hope that helps you.
-ME

-----Original Message-----
From: owner-***@openbsd.org [mailto:owner-***@openbsd.org] On Behalf
Of Steffen Beyer
Sent: Saturday, September 21, 2002 4:35 AM
To: ***@openbsd.org
Subject: DHCP relay


Hi,

I'm trying to set up relaying on a 3.1 box and stuck with a problem:
the client request gets forwarded to the server but the answer is
dropped.

Could there be a problem for dhcrelay with the different IPs for one
host?

Steffen


Details:

(192.168.1.1)
DHCP server
(192.168.2.1)
|
(192.168.2.2)
DHCP relay
(192.168.3.1)
|
(192.168.3.2)
DHCP client

relay# dhcrelay -d -i $client 192.168.2.1 # 192.168.1.1 also fails
Internet Software Consortium DHCP Relay Agent 2.0pl5-OpenBSD
Copyright 1997, 1998, 1999 The Internet Software Consortium.
All rights reserved.

Please contribute if you find this software useful.
For info, please visit http://www.isc.org/dhcp-contrib.html

Listening on BPF/de0/00:e0:29:14:5f:d7
Sending on BPF/de0/00:e0:29:14:5f:d7
Sending on Socket/fallback/fallback-net

relay# tcpdump -n -e -ttt -i $client
tcpdump: listening on de0
Sep 21 10:05:02.883927 0:4:75:62:b4:69 ff:ff:ff:ff:ff:ff 0800 590:
0.0.0.0.68 > 255.255.255.255.67: xid:0x84b4dcbe [|bootp]

relay# tcpdump -n -e -ttt -i $server
Sep 21 10:05:02.884315 0:10:f3:0:72:fc 0:4:e2:22:d4:ea 0800 590:
192.168.2.2.67 > 192.168.2.1.67: (request) xid:0x84b4dcbe
G:192.168.3.1 ether 0:4:75:62:b4:69 [|bootp]

Sep 21 10:05:02.982752 0:4:e2:22:d4:ea 0:10:f3:0:72:fc 0800 343:
192.168.2.1.67 > 192.168.3.1.67: (reply) xid:0x84b4dcbe Y:192.168.3.2
S:192.168.1.1 G:192.168.3.1 ether 0:4:75:62:b4:69 [|bootp] (DF)

server# tail syslog
Sep 21 10:05:02 a-traxx dhcpd: DHCPDISCOVER from 00:04:75:62:b4:69 via
192.168.3.1
Sep 21 10:05:02 a-traxx dhcpd: DHCPOFFER on 192.168.3.2 to
00:04:75:62:b4:69 via 192.168.3.1

[Steffen Beyer]

On Sat, 21 Sep 2002 11:35:27 -0400

Post by Michael Erdely
I found that you have to specify both interfaces.

It's running now, thank you!