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Re: [LUG] hi there!!!



hi simon,

yeah you're right from what i've read, anti-spoofing is looked after in the
routing code - check
# cat /proc/sys/net/ipv4/conf/all/rp_filter

should produce an output of '1'

but - i will certainly add it as a specific rule - and also protect the loopback
device with

ipchains -A input -i ppp0 -s 192.168.0.0/255.255.0.0 -j DENY
ipchains -A input -i ppp0 -s 10.0.0.0/255.0.0.0 -j DENY
-> er and the other one... you know - the other private network range which
no-one uses :o)

no harm with two lines of defense!

thanks for the help

kev



Simon Waters wrote:

> John Horne wrote:
>
> > As such you won't even be able to
> > fiddle ipchains to try and determine your IP address when starting. You may
> > need to connect to the ISP, get the IP address, put that into ipchains and
> > then restart it. Messy, probably automatable, but again it may well work :-)
>
> You can specify rules based on interface, but since Demon
> allocate static IP addresses I've never done this in anger.
>
> Block everything, and then allowing in the stuff from the
> Internet. If people are allowed to do things from the Internet,
> it is usually safe to let local IP addresses do the same thing!
>
> Then allow the other things using only the local static IP
> addresses, and make sure that any packets arriving on the ppp0
> interface with source addresses that ought to be inside are
> blocked (Although I think Linux does some antispoofing by
> default lets not rely on it).
>
> --
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