Hello pf,
I've found two problems today on my 3.2 release machine. I've got an
$ExtIF that connects to the Internet and an $IntIF that goes to a
NATed private net.
1) I've got a cablemodem that asigns an IP throu DHCP. But the
cablemodem itself has an 192.169.100.1 IP. So I have added an alias
192.168.100.128. Which leads to two subroblems.
1a) When I try to reach it from my NATed machine it gets translated
and so it doesn't goes throu 192.168.100.128 but my CM assigned IP.
I think that I have to add a:
nat on $ExtIF from $IntNet to ! 192.168.100.1 -> $ExtIP
Is that right? does this works on 3.2-release? If I had multiple
aliases (non consecutive) how should I do it?
1b) I want to make sure that if some machine gets compromised, it
can't send spoofed IP. So I've put:
block out quick on $ExtIF inet from ! $ExtIP to any
But it doesn't allows my aliased IP. I've tried to use a list. But
when I negate a list I get a sysntax error (which I expected
anyway). I don't think it's logical to have a list of negated IPs
since that should mean everything. How am I supposed to do this?
I've been explicitly allowing what to get out so I do:
pass out quick on $ExtIF inet proto tcp from $ExtIPalias to any \
flags S/SAFPRU keep state
pass out quick on $ExtIF inet proto tcp from $ExtIP to any \
flags S/SAFPRU keep state
pass out quick on $ExtIF inet proto udp from $ExtIP to any \
keep state
pass out quick on $ExtIF inet proto icmp from $ExtIP to any
block out quick on $ExtIF all
Which get's what I want. Is this the only way to attain what I
intend? Seems a bit cumbersome.
2) Since I'm NATing on the external interface I can't do something
like:
#Modulate weak clients sequence number
pass out quick on $ExtIF inet proto tcp from $WeakClientsIP \
to any flags S/SAFPRU modulate state
pass out quick on $ExtIF inet proto tcp from $ExtIP to any \
flags S/SAFPRU keep state
So or I modulate everything that get out (which I think would
modulate the firewall's own already excellent sequence numbers or I
have to live with the weak clients sequence numbers. Did get
something wrong or is this the way it's done?
Please keep in mind that I don't want to upgrade until 3.3 release,
so lists and such thins is a no no for now.
--
Best regards,
Alejandro Belluscio
