questions about /proc/sys/net/ipv4/conf/ on 2.2

Jim Breton (jamesb-kernel@alongtheway.com)
Tue, 21 Dec 1999 20:54:20 -0500 (EST)


Hi, sorry to post this here, I'd sent it to linux-admin without response
and am hoping someone might be able to help me out. I haven't been able
to find the answers in the kernel docs (2.2) or in any How-Tos or
anything. I will run a few tests to check some of it out but I want to
make sure I will have an understanding of what is supposed to happen so I
don't mis-interpret the results when I'm through. Though this e-mail
appears long-ish, it should only take a moment to respond if someone
wouldn't mind. :)

I notice there is a "default" directory in there, as well as an "all" and
one for each of your network interfaces. How does one know which is the
"default" interface? Also, what does the default interface imply... iow,
what changes would be inflicted by making a certain interface the default?

Does setting an option in one of the interfaces' directories override a
contradictory setting in the "all" directory? Or is it the other way
around? The kernel docs mention that "Changes in the all subdirectory
affect all interfaces, where changes in the other subdirectories affect
only one interface" but it does not say which will take precedence.

Would settings (such as accept_source_route, etc.) in this dir override
kernel firewall rules or will the rules still block source routed packets
if so configured? (Seems to me that the latter would be true.)

Also, in one of the LDP firewall How-Tos, I saw it noted that kernels
>=2.1 would auto-reject packets coming from 127.* if they were incoming on
any iface besides lo. However, I was able to spoof packets from 127.0.0.1
into my ppp0 interface from a remote box and they were not automatically
rejected (until I blocked them with ipchains). Is there something I did
wrong or was this feature removed somewhere between 2.1 and 2.2?

Lastly, each of these dirs has a "forwarding" option in it. Should this
override the setting in /proc/sys/net/ipv4/ip_forward?

TIA. Appreciate any responses (not counting flames, of course.) ;)

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/