DHCP Forwarder

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morphx21
DD-WRT Novice


Joined: 10 Jul 2006
Posts: 5

PostPosted: Mon Jul 10, 2006 19:04    Post subject: DHCP Forwarder Reply with quote
I have a Linksys WRT54GL that I have just flashed with dd-wrt. It is going to reside on a network that has its own DHCP server. I have tried turning off the DHCP server and using the forwarder to point to the stand alone DHCP server with no luck.

Currently my Internet Connection is set to static on the 128.83.87 network and I can access the router from the outside. The routers IP is still set to 192.168.1.1 with 0.0.0.0 as the gateway. DHCP Forwarder points to the DHCP server on the outside of the router.

Any ideas or suggestions?
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pugsly0014
DD-WRT Novice


Joined: 09 Jun 2006
Posts: 15

PostPosted: Mon Jul 10, 2006 19:31    Post subject: Reply with quote
It works fine for me.

I have a Windows 2003 Domain Controler with DHCP for handing out my IP's. It's IP address is 192.168.0.1. My DD-WRT is set up with an IP of 192.168.0.254 and I put the IP address address of 192.168.0.1 in the DHCP forwarder.

I have not had any problems with this.
morphx21
DD-WRT Novice


Joined: 10 Jul 2006
Posts: 5

PostPosted: Mon Jul 10, 2006 20:09    Post subject: Reply with quote
Do you have a static Ip set in the Internet Connection Type or is it disabled? Do you have 192.168.0.254 in both the Internet Connection Type and the Router IP areas of the Basic Setup page?

Under Router IP do you have 192.168.0.1 set as the Gateway?
BrainSlayer
Site Admin


Joined: 06 Jun 2006
Posts: 6103
Location: Dresden, Germany

PostPosted: Mon Jul 10, 2006 23:18    Post subject: Reply with quote
the lan network must be configured within the dhcp forwarding network. everything else will result in a invalid configuration. a router with 192.168.1.1/24 cannot provide ip's in other networks
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LK7R
DD-WRT Novice


Joined: 06 Aug 2006
Posts: 9

PostPosted: Sun Aug 06, 2006 18:16    Post subject: Reply with quote
I have simillar problem. My config is following:

two WRT54GL with DD-WRT v.23 final
WRT54GL1 - AP
WRT54GL2 - client bridged mode

schema attached in PDF

My goal is to get IP from behind DDWRT2 from Linux DHCP via DDWRT1.

When I set clients behind DDWRT2 to DHCP ... I get no IP. When I look into Linux DHCP log i get

following:

Aug 6 18:32:04 mail dhcpd: DHCPOFFER on 10.12.7.62 to 00:13:20:7e:f8:d8 via 10.12.7.7
Aug 6 18:32:20 mail dhcpd: DHCPDISCOVER from 00:13:20:7e:f8:d8 via eth0
Aug 6 18:32:20 mail dhcpd: DHCPOFFER on 10.12.7.62 to 00:13:20:7e:f8:d8 via eth0
Aug 6 18:32:20 mail dhcpd: DHCPDISCOVER from 00:13:20:7e:f8:d8 via 10.12.7.7
Aug 6 18:32:20 mail dhcpd: DHCPOFFER on 10.12.7.62 to 00:13:20:7e:f8:d8 via 10.12.7.7
[repeated many times]

I asume that is correct DHCP discover from my client and corrent answer from DHCP server ... but

DHCPOFFER never reaches my client station.

DDWRT1 10.12.7.7
- is set to AP mode
- is set to DHCP Forwarder to address 10.12.7.1
- is connected to network trough switch port (not the WAN, WAN is disabled)
- DMZ set to 10.12.7.8 (DDWRT2 address)

DDWRT2 10.12.7.8
- is set to client bridged
- is connected to network trough switch port (not the WAN, WAN is disabled)
- gw set to 10.12.7.7 (DDWRT1)



schema.jpg
 Description:
Network schema
 Filesize:  28.57 KB
 Viewed:  30247 Time(s)

schema.jpg


lord_nibbler
DD-WRT Novice


Joined: 08 Aug 2006
Posts: 2

PostPosted: Tue Aug 08, 2006 11:43    Post subject: Reply with quote
BrainSlayer wrote:
the lan network must be configured within the dhcp forwarding network. everything else will result in a invalid configuration. a router with 192.168.1.1/24 cannot provide ip's in other networks


why?

we have one big dhcp server on the LAN, this server provides dhcp for many different subnets.

our AP's are located in a different VLAN and ip network, so it would be very great if the AP's could ask the dhcp server in the LAN.

is this possible with dd-wrt or better why it should not possible?

best regards
lord_nibbler
DD-WRT Novice


Joined: 08 Aug 2006
Posts: 2

PostPosted: Tue Aug 08, 2006 15:53    Post subject: Reply with quote
maybe i should explain a little bit more what i wanna do:

i have 4 AP's with the same SSID and WPA2+AES enabled (of course div. channels)
they are located in a VLAN (WLAN) with subnet 192.168.2.0/24

this subnet is connected with a router (hp procurve switch) to the LAN (default VLAN) with subnet 192.168.1.0/24

on the LAN (192.168.1.0) there is a big dhcp server that should provide dhcp services for the WLAN clients. the 4 AP's should forward dhcp requests to this server.

of course i can configure the switch to dhcp relay between the 2 VLANs.. but in the feature i will disable routing and but a firewall between the 2 vlans for better security.

so currently this setup works.. an it works very fine... the only problem is the dhcp relay option that does not work..

any hints or tips?


best regards
wolfgang
OpsCenter
DD-WRT User


Joined: 14 Jun 2006
Posts: 218

PostPosted: Tue Aug 08, 2006 21:27    Post subject: Reply with quote
I just tried to use the DHCP Forward today with a Buffalo WHR-HP, and it didn't work either. Thought it was something that I didn't understand.

OpsCenter
klaasb01
DD-WRT Novice


Joined: 14 Aug 2006
Posts: 2

PostPosted: Mon Aug 14, 2006 20:32    Post subject: DHCP Forwarder Reply with quote
dhcp-fwd will forward requests for different subnets
eg
DCHP Server is at 192.168.36.2
WAN IP of DD-WRT 192.168.36.3
br0 IP is 192.168.77.1
vlan2 (port 0 WRT54GL) is 192.168.66.1
I can pull 192.168.66.x and 192.168.77.x addresses from DHCP.
Just add "if vlan2 true false true" to /tmp/dhcp-fwd/dhcp-fwd.conf and restart it.

You may have to add a route back to those subnets on the DHCP server.
eg. on windows route add 192.168.66.1 mask 255.255.255.0 192.168.36.3 metric 1 if 0x1


Last edited by klaasb01 on Tue Aug 15, 2006 18:17; edited 2 times in total
heyyosupz
DD-WRT Novice


Joined: 08 Jul 2006
Posts: 9
Location: U.S

PostPosted: Mon Aug 14, 2006 20:49    Post subject: Reply with quote
"the lan network must be configured within the dhcp forwarding network. everything else will result in a invalid configuration. a router with 192.168.1.1/24 cannot provide ip's in other networks "

according to BS's statement, the dhcp fowarder can ONLY forward the client to the DHCP SERVER "within" the "SAME SUBNET". i guess there may be difference between dhcp forwarding and dhcp relay or bootp, right?
lampie
DD-WRT Novice


Joined: 22 Aug 2006
Posts: 1

PostPosted: Tue Aug 22, 2006 18:01    Post subject: Reply with quote
I was also havind troubles, but after 3 days of tinkering i got it working again. DONT use the switch for DHCP forwarding. This will work but somehow the network performace is really awfull. The connection drops in intervals, so something is not right. Use the WAN port for the internet (as it should) and the switch for the computers to connect.

At SETUP

Basic setup

then

VLANs

Vlan 1 (the one where W is checked) click the drop down list box and set this to LAN.

Save settings and it should work :D

Greetings Lampie
iso
DD-WRT Novice


Joined: 31 Aug 2006
Posts: 16
Location: West Chester, PA

PostPosted: Thu Aug 31, 2006 6:28    Post subject: Reply with quote
I took your advice, lampie. It seems to be passing DHCP requests to the server now, but i'm still having issues. Here are the logs from my DHCP Server (Smoothwall) - 192.168.1.1.

Aug 31 11:22:24 loki dhcpd: DHCPDISCOVER from 00:18:39:aa:38:68 via eth0
Aug 31 11:22:24 loki dhcpd: DHCPOFFER on 192.168.1.68 to 00:18:39:aa:38:68 via eth0
Aug 31 11:22:31 loki dhcpd: DHCPDISCOVER from 00:18:39:aa:38:68 via eth0
Aug 31 11:22:31 loki dhcpd: DHCPOFFER on 192.168.1.68 to 00:18:39:aa:38:68 via eth0
Aug 31 11:22:38 loki dhcpd: DHCPDISCOVER from 00:18:39:aa:38:68 via eth0

It looks like its taking the source MAC of my WAN interface instead of the MAC on my Laptop Wireless interface. So it eventually times out after trying to get an IP. Any insight into this?

LAN MAC 00:18:39:AA:38:67
WAN MAC 00:18:39:AA:38:68
Wireless MAC 00:18:39:AA:38:69

DD-WRT v24 Beta (08/20/06) std
iso
DD-WRT Novice


Joined: 31 Aug 2006
Posts: 16
Location: West Chester, PA

PostPosted: Fri Sep 01, 2006 23:09    Post subject: Reply with quote
Works in dd-wrt.v23 SP2 2006 - 0823, but not in dd-wrt.v24 beta 2006 - 0823
rkloost
DD-WRT Guru


Joined: 11 Jul 2006
Posts: 1247
Location: Nijmegen, The Netherlands

PostPosted: Fri Sep 01, 2006 23:22    Post subject: Reply with quote
There are newer builds, try them please...

Bugfixing is work in progress...

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iso
DD-WRT Novice


Joined: 31 Aug 2006
Posts: 16
Location: West Chester, PA

PostPosted: Sat Sep 02, 2006 2:59    Post subject: Reply with quote
Works in dd-wrt.v24 beta 2006 - 0830! Very Happy
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