Hello, i'd like to understand more deeply xen networking. My purpose is to modify the dscp ip field in guest's packet, to perform Qos, thanks to iptables. I'm using a FC7 with xen 3.1. I've installed a windows guest, with virt-manager, and I have used the default nat network option. Unfortunatelly, i couldn't use the bridge option because no network card was proposed! but this isn't the subject... I was quite surprised when i saw, in my xen-config.sxp : (network-script : network-bridge). it should be network-nat, am I wrong? the ifconfig command displays : lo Link encap:Boucle locale inet adr:<a href="http://127.0.0.1">127.0.0.1</a> Masque:<a href="http://255.0.0.0">255.0.0.0</a> adr inet6: ::1/128 Scope:Hôte UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:731062 errors:0 dropped:0 overruns:0 frame:0 TX packets:731062 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:0 RX bytes:7695075004 (7.1 GiB) TX bytes:7695075004 (7.1 GiB) tap0 Link encap:Ethernet HWaddr 82:E3:26:59:DC:BF adr inet6: fe80::80e3:26ff:fe59:dcbf/64 Scope:Lien UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:17783 errors:0 dropped:0 overruns:0 frame:0 TX packets:513 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:500 RX bytes:24458454 (23.3 MiB) TX bytes:181392 (177.1 KiB) tmpbridge Link encap:Ethernet HWaddr 00:00:00:00:00:00 inet adr:<a href="http://192.168.1.5"> 192.168.1.5</a> Bcast:<a href="http://192.168.1.255">192.168.1.255</a> Masque:<a href="http://255.255.255.0">255.255.255.0</a> adr inet6: fe80::200:ff:fe00:0/64 Scope:Lien UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:34 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:0 RX bytes:0 (0.0 b) TX bytes:9046 ( 8.8 KiB) vif11.0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF UP BROADCAST MULTICAST MTU:1500 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 lg file transmission:32 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) virbr0 Link encap:Ethernet HWaddr 82:E3:26:59:DC:BF inet adr:<a href="http://192.168.122.1">192.168.122.1 </a> Bcast:<a href="http://192.168.122.255">192.168.122.255</a> Masque:<a href="http://255.255.255.0">255.255.255.0</a> adr inet6: fe80::200:ff:fe00:0/64 Scope:Lien UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:21958 errors:0 dropped:0 overruns:0 frame:0 TX packets:1377 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 lg file transmission:0 RX bytes:24771762 (23.6 MiB) TX bytes:304511 (297.3 KiB) the "network-bridge status" displays : ============================================================ 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet <a href="http://127.0.0.1/8">127.0.0.1/8</a> scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: peth0: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:08:02:f5:71:e6 brd ff:ff:ff:ff:ff:ff 3: virbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue link/ether 82:e3:26:59:dc:bf brd ff:ff:ff:ff:ff:ff inet <a href="http://192.168.122.1/24"> 192.168.122.1/24</a> brd <a href="http://192.168.122.255">192.168.122.255</a> scope global virbr0 inet6 fe80::200:ff:fe00:0/64 scope link valid_lft forever preferred_lft forever 4: tmpbridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff inet <a href="http://192.168.1.5/24">192.168.1.5/24</a> brd <a href="http://192.168.1.255">192.168.1.255</a> scope global tmpbridge inet6 fe80::200:ff:fe00:0/64 scope link valid_lft forever preferred_lft forever 21: vif11.0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 32 link/ether fe:ff:ff:ff:ff:ff brd ff:ff:ff:ff:ff:ff 22: tap0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 500 link/ether 82:e3:26:59:dc:bf brd ff:ff:ff:ff:ff:ff inet6 fe80::80e3:26ff:fe59:dcbf/64 scope link valid_lft forever preferred_lft forever it seems like the network-bridge scripts crashes, because the tmpbridge is not renamed, and when I start the xend service or when I run network-bridge start, the eth0 interface is disable!! can anyone helps me debug this situation? thanks