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Re: Help with ipchains on Potato -- problem with -s?

Looks like a problem with reverse-DNS.  Does ipchains -L *chain* -n hang?


>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 10/11/2001, 2:38:08 PM, Marc Ozon <marc.ozon@utoronto.ca> wrote 
regarding Help with ipchains on Potato -- problem with -s?:

> Hash: SHA1

> Hi,

> 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 
> 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 -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.
> Absolutely maddening.

> Any ideas?  Anything I'm missing, or anywhere else I can check?

> Thanks,
> Marc

> Version: GnuPG v1.0.6 (OpenBSD)
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> =9M/Z

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