DHCP fails on Guest WinXP32 bridged to Host Redhat 5

nekenyu · Post by **nekenyu** » 10. Sep 2008, 06:21

Hi,

I looked, but didn't quite find my issue... But, there are unfortunately a lot of topcis... so..

My RedHat 5 system connects by ethernet and dhcp. I followed the manual (without errors) in setting up bridging. WinXP Guest has network device, but DHCP fails to the "Limited or no network connectivity."

However, if I manually set the IP, the host and guest can ping each other, the host can reach the router (dsl router with web configurationi). Unfortunately, using the same DNS server on the guest as the server (the dsl router itself) fails DNS lookups.

Host has full network, including DHCP and DNS. Using NAT instead of host works.

Configuration:

Host: RedHat5 x86_64. Guest: Windows XP 32.
eth0 bridged to br0 (per manual / redhat directions).
Created vbox0 (per manual / redhat directions VBoxAddIF).
No errors reported.

Code: Select all

br0       Link encap:Ethernet  HWaddr 00:1C:23:86:93:15
          inet addr:192.168.1.71  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::21c:23ff:fe86:9315/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:23365 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13931 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:14404342 (13.7 MiB)  TX bytes:2104030 (2.0 MiB)

eth0      Link encap:Ethernet  HWaddr 00:1C:23:86:93:15
          inet6 addr: fe80::21c:23ff:fe86:9315/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:16986 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10843 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:9016518 (8.5 MiB)  TX bytes:1758642 (1.6 MiB)
          Interrupt:185

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3351 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3351 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:7268777 (6.9 MiB)  TX bytes:7268777 (6.9 MiB)

vbox0     Link encap:Ethernet  HWaddr E2:AA:4A:AD:A6:6E
          inet6 addr: fe80::e0aa:4aff:fead:a66e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:638 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2871 errors:0 dropped:146 overruns:0 carrier:0
          collisions:0 txqueuelen:500
          RX bytes:100175 (97.8 KiB)  TX bytes:371731 (363.0 KiB)

Reason for bridging: I intend for tje Guest WinXP to run VPN and route relevant Host Linux traffic over VPN. (I'm not sure the particular VPN client will support that -- Checkpoint VPN-1 Client, but i'll burn that bridge...)

Do I need to have a NAT interface to run the VPN out and a manually configured bridged connection for the host to reach the guest? Or am I missing something obvious?

Post by **Sasquatch** » 10. Sep 2008, 10:27

There are a few things that could matter.
Do you have any firewall running on the Host or guest that might interfere with DHCP?
How does the router/modem act if you powercycle it when the Guest is requesting an IP address? It might give only one IP and records the MAC address of the interface that requested an IP and then denies any other interface.
Your eth0 interface is wireless (you don't say this, I'm assuming wired) and as per the VirtualBox FAQ a bridge does not support a wireless interface.

Please see the Forum Posting Guide and give some more information.

nekenyu · Post by **nekenyu** » 10. Sep 2008, 14:00

The firewall is disabled on the guest and, to my knowledge, is not running on the host. The host networking is across a wired ethernet. I will try the power-cycling of the DSL router this evening.

Post by **Sasquatch** » 10. Sep 2008, 15:23

If you get a private network address you can also set a static address on the Guest. If you power cycle the modem/router, be sure to deny the host to obtain an address. That way, you can be sure that the Guest will be able to obtain one. To deny the Host an address, set a static one.

nekenyu · Post by **nekenyu** » 10. Sep 2008, 15:32

Are you saying that only the host or the guest can use DHCP from the router?

Post by **Sasquatch** » 10. Sep 2008, 17:17

That depends on the router. The modem of someone I fixed the computer for had this issue. When I hooked my laptop on the connection (no router or anything, just a single LAN connection on the modem) I wasn't able to obtain an IP address until I power cycled the device. When the computer was running again, I had to power cycle it again for it to accept the computer. If this is the case, you need a separate router so more than one computer can use the same connection.

Post by **Martin** » 11. Sep 2008, 11:19

nekenyu wrote:The firewall is disabled on the guest and, to my knowledge, is not running on the host.

Make sure that there is no firewall on the host blocking IP forwarding. (and that IP forwarding is not disabled)