I followed the Paravirtualization With Xen On CentOS 5.6 (x86_64) howto. Everything went fine and in fact everything described in the howto work as described, the only problem I have is that after I reboot into the Xen kernel network connectivity is gone. I can login to the server on the physical console, but I can't ssh (putty) into it anymore. If I go to the physical console I can't ping anything either. My infrastructure is pretty standard, a home network with ADSL connection through a standard router. A couple of PC's on the network, some Windows and some Linux. The Xen server has been setup with static IP 192.168.1.51. The ADSL gateway is 192.168.1.1. Before installing Xen, the network works fine on the Xen server, in fact I install xen and xen-kernel using yum. So far no problem. ifconfig shows just eth0 with 192.168.1.51 and lo. After Xen has been installed and rebooted ifconfig shows a long list of interfaces, most without IP addresses: eth0 (still with 192.168.1.51), lo, peth0, veth1-3, vif0.0-0.3, virbr0 with 192.168.122.1 and xenbr0. xm list shows one VM, Domain-0. I'm not sure I fully understand Xen at this time, is Domain-0 what I am logged into or is that a separate VM? I can't connect to it or anything, but it's listed. Maybe I'm just completely misunderstanding everything, but shouldn't I still be able to ssh into this hardware box and proceed creating VM's through putty? Do I really have to sit in front of the physical box for that?
Decided to restart from scratch, re-installed Centos 5.6, verified network works fine, confirms no hardware or network problem causing this. Installed Xen with yum as per the howto, rebooted and again no network access. modprobe/lsmod show the NIC hardware ip link shows NIC up ip route shows correctly "default via 192.168.1.1 dev eth0" What am I missing here?
Changed NIC, that fixed the problem. There must have been some kind of conflict between Xen and the original NIC.
Domain-0 AKA dom0 AKA the hypervisor in paravirtualization is the host OS, the OS you installed the Xen kernel on and the OS you're going to use to create guests OSes AKAs domUs. Make sure sshd is installed, configured and running. Since you are using ADSL, make sure you open port 22 or your SSH port in your hardware firewall if you have one. Code: iptables -F will flush all your software firewall rules so you can configure from scratch.
