On Thursday 07 July 2005 15:34, Richard B. Johnson wrote: > >> Only the 127.0.0.0 network should be routed through the loop-back > >> device. > > > > Again: All the IP addresses mentioned are local to this box. > > > > If you ping an IP address on your eth0, the traffic will "go" > > over loopback. You can verify it using tcpdump: > > > > If you ping an IP address on your computer, the traffic will go > through lo. However, I think that the IP address shown is > the result of an instrumentation error because it is impossible > to put, for instance your 192.168.1.1, through a 127.0.0.0 network, > the ONLY route through lo. This shows that 'local' traffic bypasses > the lo route filtering altogether. You can verify this by > deleting the lo route altogether, you can still ping the local > addresses. > > Somebody else mentioned that lo was 'perfectly happy' to > carry whatever. The fact that something bogus appears on > lo can be a sign of a misconfiguration error, just as > the reserved 127.0.0.0 network must never appear on ethernet.
Care to tcpdump your own lo? > In the case of 0.0.0.0 (a possible broadcast), there is > no "local" address that could cause a bypass via lo. Instead, > any such traffic should have been on the ethernet wire. This > shows the possible configuration error that I mentioned. > > > > 1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue > > link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 > ^^^^^^^^^^^^^^^^ > > inet 127.0.0.1/8 scope host lo > > This looks as though there is no netmask set. My configuration > shows: BS. 00:00:00:00:00:00's above aren't netmasks. > 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 > > This is a possible configuration error. Yours is ifconfig output, whereas "link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00" line above was from ip, not ifconfig. -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
