xen network bridge problem

[Sounds]

Hi everyone.

I'm running CentOS 5.7 with xen installed via the Virtualization yum group.

I installed an Ubuntu 11.04 domU with virt-manager and have configured the network bridge according to the guide here:
wiki.kartbuilding.net/index.php/Xen_Networking]Xen Networking - Wiki

I also changed the mac address according to the recommendation here:
adminstuff.wikidot.com/xen-bridge-networking]Xen Bridge Networking - Adminstuff

I am able to ping the IP of the domU from dom0 and vice versa, but I cannot access the internet from the domU. Any suggestions?

my iptables don't show forwarding to vif1.0 the the domU's IP address.

# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     udp  --  anywhere             anywhere            udp dpt:domain 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:domain 
ACCEPT     udp  --  anywhere             anywhere            udp dpt:bootps 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:bootps 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             192.168.122.0/24    state RELATED,ESTABLISHED 
ACCEPT     all  --  192.168.122.0/24     anywhere            
ACCEPT     all  --  anywhere             anywhere            
REJECT     all  --  anywhere             anywhere            reject-with icmp-port-unreachable 
REJECT     all  --  anywhere             anywhere            reject-with icmp-port-unreachable 
ACCEPT     all  --  max                  anywhere            PHYSDEV match --physdev-in vif1.0 
ACCEPT     udp  --  anywhere             anywhere            PHYSDEV match --physdev-in vif1.0 udp spt:bootpc dpt:bootps 

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Here's the config for my VM:

# cat /etc/xen/rm 
name = "rm"
maxmem = 512
memory = 404
vcpus = 2
builder = "hvm"
kernel = "/usr/lib/xen/boot/hvmloader"
boot = "c"
pae = 1
acpi = 1
apic = 1
localtime = 0
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
device_model = "/usr/lib64/xen/bin/qemu-dm"
sdl = 0
vnc = 1
vncunused = 1
keymap = "en-us"
disk = [ "file:/var/lib/xen/images/rm.img,hda,w", ",hdc:cdrom,r" ]
vif = [ "mac=02:00:00:00:00:01,ip=___.__.___.16" ]
parallel = "none"
serial = "pty"

Any help is much appreciated!

[um_nirvani]

You will need to check the vif configuration. I have a VM and its config reads as:

vif = [ 'mac=___MAC___, bridge=xenbr0', 'bridge=virbr0', ]

This link could help you:
Guest Configuration

[carloxavier]

I crossed my path to the same problem,

I installed Xen3.0 and several Debian Etch on DomU's that worked just fine,
Then I Installed an Ubuntu Natty (11.04) as another DomU, and I got no internet at all...
the problem was the MTU:

etch:~# ifconfig

eth0      Link encap:Ethernet  HWaddr 00:16:3E:74:CB:77  
          inet addr:192.168.11.101  Bcast:255.255.255.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:576  Metric:1
          RX packets:1809 errors:0 dropped:0 overruns:0 frame:0
          TX packets:172 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:478086 (466.8 KiB)  TX bytes:23465 (22.9 KiB)
          Interrupt:26 

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:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

natty:~# ifconfig

eth0      Link encap:Ethernet  HWaddr 00:16:3E:74:CA:21  
          inet addr:192.168.11.102  Bcast:255.255.255.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1809 errors:0 dropped:0 overruns:0 frame:0
          TX packets:172 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:478086 (466.8 KiB)  TX bytes:23465 (22.9 KiB)
          Interrupt:26 

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:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

So I changed the mtu of the Natty girl:

natty:~# ifconfig eth0 mtu 576

and everything is working fine now