# Xen dom0 networking

## Crisis

I'm building a virtual server with Xen, and I'm having an odd issue.  The dom0 can not access the outside network.  The domUs can connect fine, however.  Additionally, the domUs can connect to the dom0.

So basically I am trying to establish connectivity to/from remote hosts and the dom0.

I'm using the default networking setup, as a bridge.  So I'm guessing the issue is with the bridge.  Anyone have any ideas or places to start?  Thanks!

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## anello

 *Crisis wrote:*   

> ... Anyone have any ideas or places to start?  Thanks!

 

Xen 3.0 Documentation  :Wink: 

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## Crisis

I've read the docs, I'm looking for help with my issue....

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## abombss

I too am in need of some networking help.  I have a bonded interface bond0 consisting of eth0 and eth1 and I cann't get any configurations working.  Anyone running xen-3.0.3+ that can enlighten us on how networking is done under gentoo.

My conf.d/net

config_eth0=("null")

config_eth1=("null")

bond0_slaves=eth0 eth1

config_bond0=("10.1.10.24/24")

routes_bond0=("default via 10.1.10.1")

I added net.bond0 to init.d default

When I boot my bond works fine, however as soon as I start xend nothing works.  It seems like my ip address and mac address do not copy.

I have even changed the xend-config.sxp (network-bridge 'network-bridge netdev=bond0') and still nothing.

Can someone post a working ifconfig -a and route -n for pre xend start and post xend start, also a conf.d/net file, xend-config.sxp, and rc-update show would also be helpful.

Thank you,

Adam

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## Berra

I got a similar problem, maby it's the same. When I start xend conntrack seems to mark all packats as invalid. So the network works when not using conntrack but not with.

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## Crisis

I had to update the firmware on my IBM xSeries server's onboard NetXtreme II card, and it fixed the issue.

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## Age_M

Hi,

i don't know if it is really the problem, but let's see...

 *abombss wrote:*   

> 
> 
> I added net.bond0 to init.d default
> 
> 

 

I think this is wrong. you only should have net.lo in your boot runlevel and no net.* in the default. the physical network-device should be started by xend, because xend needs to set the MAC-address of your physical netdev to ff:ff:ff:ff:ff:ff. this mac address is needet to connect a physical netdev to a bridge IIRC.

so, try to remove net.bond0 and just add xend to your default runlevel. everything should work just fine now. if it doesen't and the init of xend hangs, just restart the machine, do the interactive init and skip xend.

hope this helps

Greetz Age_M

PS: sorry for my poor english  :Wink: 

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## thepustule

 *anello wrote:*   

>  *Crisis wrote:*   ... Anyone have any ideas or places to start?  Thanks! 
> 
> Xen 3.0 Documentation 

 

Uh, yeah.  

Ok, first, the Gentoo xen wiki says that you are supposed to stop the net.eth0 scripts from running at startup.  Then the Xen 3.0 documentation says that the xen network scripts copy the IP address and Mac address from the "real" interface to the xen virtual bridge interface.  So, if I stop the net.eth0 script from running, there is no IP address to copy.  Not only that, but Xen isn't copying the Mac address either.  It's all F's, with one E.  The documentation says that the MAC will be randomly generated from the 00:16:3E:xx:xx:xx range.  But it's not.

Oh that's really clear...

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## Age_M

Hi,

 *Quote:*   

> Xen isn't copying the Mac address either.  It's all F's, with one E.  The documentation says that the MAC will be randomly generated from the 00:16:3E:xx:xx:xx range.  But it's not.
> 
> 

 

afaik, that is correct: the original eth0 is renamed to peth0 and eth0 is a new interface connected to the bridge. because of that the new eth0 get's a mac fe:ff:ff:ff:ff:ff.

Greetz Age_M

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## thepustule

no, on my system the eth0 keeps the "real" MAC address, but peth0 is added to the bridge.  In any case, it works ok.

I had to mknod /dev/net/tun before my vms would start.  That took me a while to figure out...

In all, Xen is one of the sloppiest software projects I've ever seen.  All of the "official" documentation on their site (such as it is, which is bad) is out of date.  Config files undergo massive changes between minor releases, and comprehensive lists of features are hard to find.  The only way to figure out how to do anything is google the personal blogs of people who have wrestled through it before.

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