Hello, I use bridge to give user-mode-linux boxs an Internet access When the uml-host is connected to the gateway via a cross-wired cable, everything works fine. If I put a hub (I've also make tests with another hub and a switch) between the host and the gateway, uml-guests no more see the gateway (and therefore no more see the Internet) In both case the uml-host can ping the gateway and the uml-guests, the gateway can always ping the uml-host, and the uml-guests can always ping the uml-host: * direct cross wired cable between umlhost and gateway: [umlhost:br2:192.168.1.2/24] -------- [gateway:eth4:192.168.1.1/24] | | [uml1:eth0:192.168.1.3/24] umlhost# ping 192.168.1.1 is OK umlhost# ping 192.168.1.3 is OK uml1# ping 192.168.1.1 is OK * a hub (or a switch) between umlhost and gateway [umlhost:br2:192.168.1.2/24] --[hub]-- [gateway:eth4:192.168.1.1/24] | | [uml1:eth0:192.168.1.3/24] umlhost# ping 192.168.1.1 is OK umlhost# ping 192.168.1.3 is OK uml1# ping 192.168.1.1 no response gateway# ping 192.168.1.3 no response I've noticed that dmesg gives me lot of lines like theses: eth2: received packet with own address as source address eth2: received packet with own address as source address ... I first think about a MAC adress sort of conflict, so I take care of assigning specifics ones to the uml-guests, but no changes. What did I miss ? Thanks, Olivier. PS: my current configuration look like this: host kernel is a 2.4.22 (with almost all security patchs, skas3, and cryptoloop) SMP enabled on a dual PIII/400 (cannot try latest 2.4 kernel now, it's planned) umlhost# brctl show bridge name bridge id STP enabled interfaces br2 8000.0080c8e8ac3f no eth2 tap0 umlhost# brctl showmacs br2 port no mac addr is local? ageing timer 1 00:00:e8:3d:be:81 no 202.29 (this is the gateway) 1 00:80:c8:e8:ac:3f yes 0.00 (this is eth2) 2 00:ff:c0:6a:b1:46 yes 0.00 (this is tap0) 2 fe:fd:0a:00:00:01 no 218.27 (this is eth0 inside uml) umlhost# ifconfig eth2 eth2 Link encap:Ethernet HWaddr 00:80:C8:E8:AC:3F UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:1029587 errors:0 dropped:5 overruns:0 frame:104 TX packets:2307201 errors:3 dropped:0 overruns:3 carrier:0 collisions:0 txqueuelen:100 RX bytes:152173060 (145.1 MiB) TX bytes:3011077736 (2.8 GiB) Interrupt:18 Base address:0x9000 umlhost# ifconfig tap0 tap0 Link encap:Ethernet HWaddr 00:FF:C0:6A:B1:46 UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1 RX packets:7595 errors:0 dropped:0 overruns:0 frame:0 TX packets:7641 errors:0 dropped:2 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:6853964 (6.5 MiB) TX bytes:732177 (715.0 KiB) umlhost# ifconfig br2 br2 Link encap:Ethernet HWaddr 00:80:C8:E8:AC:3F inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:4019 errors:0 dropped:0 overruns:0 frame:0 TX packets:1342 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:394739 (385.4 KiB) TX bytes:184260 (179.9 KiB) uml1:~# ifconfig eth0 eth0 Link encap:Ethernet HWaddr FE:FD:0A:00:00:01 inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::fcfd:aff:fe00:1/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:7641 errors:0 dropped:0 overruns:0 frame:0 TX packets:7595 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:625203 (610.5 KiB) TX bytes:6853964 (6.5 MiB) Interrupt:5 gateway# ifconfig eth4 eth4 Link encap:10Mbps Ethernet HWaddr 00:00:E8:3D:BE:81 inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:6188 errors:0 dropped:0 overruns:0 TX packets:5398 errors:0 dropped:0 overruns:0 Interrupt:12 Base address:0xc400