Help with ipchains on Potato -- problem with -s?
-----BEGIN PGP SIGNED MESSAGE-----
I've been trying to configure a firewall using ipchains on a machine
running pretty much a stock installation of Potato -- I've done the apt-get
upgrade but not dist-upgrade. My kernel is the default 2.2.19pre17, and
given that /proc/net/ip_fwchains exists, I figure it has the appropriate
support for using ipchains.
My problem is this: whenever I use ipchains to try to filter by source
address, i.e. with -s x.x.x.x/x as an option, something goes wrong.
Details (I'll use *chain* to stand for any one of the chains):
All the following ipchains commands work properly (i.e. checking with
ipchains -L returns an intelligible response, and the packet filter seems
to behave as it should given the ipchains commands):
ipchains -F *chain*
ipchains -P *chain* DENY
ipchains -A input -i lo -j ACCEPt
ipchains -A input -i eth0 -p tcp ! -y -j ACCEPT
ipchains -A input -i eth0 -p icmp --destination-port 0 -j ACCEPT
ipchains -A input -j DENY -l
BUT when I try to filter by source address, e.g.
ipchains -A input -i eth0 -s 192.168.0.0/16 -j DENY
and check with ipchains -L to see my rule set, ipchains -L just seems to
hang, and prints out just this:
Chain input (policy ACCEPT):
target prot opt source destination ports
I have to hit ctrl-c to get the prompt back.
When I look at /proc/net/ip_fwchains, it seems that rules with -s options
make a change there (i.e. it looks like the rule gets registered there,
when I check that file with more), but ipchains -L just hangs there.
One more complication: this doesn't happen every time. Oddly, sometimes
my whole firewall script runs and everything works -- I get a proper
response from ipchains -L. But sometimes it doesn't. I've tried to
establish a pattern, but other than noting that it seems to be using
ipchains with the -s option that triggers it, I can't seem to detect
anything that might indicate why it works sometimes but not others.
Any ideas? Anything I'm missing, or anywhere else I can check?
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (OpenBSD)
Comment: For info see http://www.gnupg.org
-----END PGP SIGNATURE-----