problems with DHCP over wifi

[RomanJB]

I need a help of a network guru. I am testing a wireless client bridge/router. I have a wired LAN with Netscreen router acting as DHCP server. I have a Motorola AP on the same subnet, which works fine - I can access the subnet and internet by connecting my PowerBook, using DHCP, through this AP. Now I am trying to use a Senao wifi bridge to to access the network. I am connecting the PowerBook to the wired LAN on the Senao. The Senao runs Linux Net4.0. I want the Senao to connect wirelessly through Motorolla to my subnet and bridge my laptop to it.

This is what happens in the bridge mode:
1. When I assign my laptop a static IP from my subnet, I can connect. However, DNS resolution doesn't work for my subnet. Dig resolves names fine, but ping and email do not. I have a DNS server on my subnet. DNS resolution for outside net works fine (using the same server).

2. When I set my laptop to "using DHCP with manual address" everything works fine, including local subnet(domain) resolution.

3. When I set it to DHCP client, the laptop doesn't get an IP address from the server, it displays a default IP of 169.254.120.172, which of course doesn't work at all.

In the router mode behavior is similar - the WLAN side doesn't want to get an IP through DHCP, but static IP works.

Two questions:

1. Any hint where to look for problems. Is it my network setup? Is it going through wifi? Is it the Senao box? BTW. The DHCP server (netscreen box) reports assigning an IP to WLAN MAC in the router mode, but the Senao keeps waiting.

2. Out of curiosity: why DNS works in DHCP mode (with manual address) and doesn't in pure static mode?

Thanks much,

Roman

 

[Captain-M]

Im not sure if you configured the gateway (eg TCP/IP 192.168.1.1) then reboot. When you get a 169.x.x.x address, this is a private address, because the DNS name is not resolved. Type in DOS shell (at start/run CMD). Enter IPCONFIG -ALL. See if the DNS server is listed. Then IPCONFIG -RELEASE, wait for reply, IPCONFIG -RENEW. If you have a firewall, this may be blocking the DHCP requests.

 

[RomanJB]

In the bridge mode the Senao box is not (and should not be) visible to my laptop, so its address doesn't matter. Interestingly with "DHCP with manual address" it gets a gateway address from DHCP server and things work well.

In the client router mode, it is the router that is supposed to get its IP through DHCP, and it fails.

It appears that Linux NET4.0 has some problems with DHCP client setup.

Im not sure if you configured the gateway (eg TCP/IP 192.168.1.1) then reboot. When you get a 169.x.x.x address, this is a private address, because the DNS name is not resolved. Type in DOS shell (at start/run CMD). Enter IPCONFIG -ALL. See if the DNS server is listed. Then IPCONFIG -RELEASE, wait for reply, IPCONFIG -RENEW. If you have a firewall, this may be blocking the DHCP requests.

 

[Madwand]

In the bridge mode the Senao box is not (and should not be) visible to my laptop, so its address doesn't matter.

I'm not familiar with the Senao box, but with a hacked (DD-WRT) Linksys wireless client bridge that I have here, I can see it from both sides of the bridge, at its assigned static address (and everything is on the same subnet here). You'd need to be able to see the bridge box for maintenance, and a static address makes that easier.

Your setup seems to be out of my depth, but based on what you've written I'd suspect the Senao box's implementation. You may be right to suspect that it might be something deeper with your DHCP / DNS implementation, but that's out of my depth...

So my suggestion is to try Senao support, or another box with a different client bridge mode implementation. SMC is sometimes recommended at the lower end of the higher end. The Linksys WRT54GL + DD-WRT is of course at the bottom end of price. There's a D-Link AP/bridge at the low end, among a handful of other products.

 

[RomanJB]

In the bridge mode the Senao box is not (and should not be) visible to my laptop, so its address doesn't matter.

I'm not familiar with the Senao box, but with a hacked (DD-WRT) Linksys wireless client bridge that I have here, I can see it from both sides of the bridge, at its assigned static address (and everything is on the same subnet here). You'd need to be able to see the bridge box for maintenance, and a static address makes that easier.

I meant only to say that in the bridge mode it doesn't serve as a gateway, so setting its IP as a gateway on the laptop wouldn't work. I can see the bridge if I set it right.

Update: I tried connecting to a public network and it worked. A PC bihind it got its IP from a DHCP server fine. The client router mode didn't work though.

So it seems that maybe my Motorolla AP doesn't work well with the Senao box.

Roman