Re: natd port forward times out, tcpdump yields nothing

Kage wrote:
Well, no, see it's hitting natd just fine as shown by my natd verbose
logs, if you're assuming ipfw is blocking me from reaching natd. Are
you talking about adding a firewall rule for each of my round-robin
addresses, too?

Yes

How would that do any good?

All response paquet to a paquet diverted to natd must also be diverted to natd to be reverse translated. eg:

incoming request from client (c) to server (s) redirected to server (S)

c.c.c.c -> s.s.s.s nated as c.c.c.c -> S.S.S.S

must have response paquetd reverse translated:

S.S.S.S -> c.c.c.c nated as s.s.s.s -> c.c.c.c

to be a valid response to client (c).


On Sat, Mar 22, 2008 at 9:27 AM, Henri Hennebert <hlh@xxxxxxxxxx> wrote:
Kage wrote:
> Hey guys,
>
> This is a fun one that's stumped people in Freenode ##freebsd.
> Basically, I have this layout:
>
> irc.domain.com -> DNS A -> IRC Jail
>
> When someone connects to irc.domain.com on IRC ports (6667, 8067,
> etc.), it round-robins them using natd, otherwise it sends all other
> port requests to the IRC jail as per normal (such as port 80, which is
> my primary concern). As for having it setup to have ipfw divert to
> natd, that's done and works, as shown by natd verbose mode:
>
> In {default}[TCP] [TCP] 72.65.73.23:2980 -> 207.210.114.45:6667 aliased to
> [TCP] 72.65.73.23:2980 -> 207.210.114.45:6667
>
> (For reference)
> 207.210.114.45 = jail IP
> 72.20.28.202 = example target IP in the round-robin
> 72.65.73.23 = my IP
>
> Right now, my ipfw.rules file is as follows:
>
> [root@nub /etc]# cat ipfw.rules
> IPF="ipfw -q add"
> ipfw -f -q flush
>
> #loopback
> $IPF 10 allow all from any to any via lo0
> $IPF 20 deny all from any to 127.0.0.0/8
> $IPF 30 deny all from 127.0.0.0/8 to any
> $IPF 40 deny tcp from any to any frag
>
> # statefull
> $IPF 50 check-state
> $IPF 60 allow tcp from any to any established
> $IPF 70 allow all from any to any out keep-state
> $IPF 54999 allow icmp from any to any
>
> # Include the deny file
> . /etc/ipfw.deny
>
> [snip -- some allowed ports]
> # IRC (natd divert for IRC port-forwarding
> $IPF 50220 divert natd all from any to 207.210.114.45 6667 via rl0
> $IPF 50230 divert natd all from any to 207.210.114.45 8067 via rl0
> $IPF 50240 divert natd all from any to 207.210.114.45 8068 via rl0
> $IPF 50250 divert natd all from any to 207.210.114.45 6697 via rl0
> $IPF 50260 divert natd all from any to 207.210.114.45 7000 via rl0


You must also divert the response trafic AFAIK eg:

$IPF 50220 divert natd all from 72.20.28.202 6667 to 207.210.114.45 via rl0



> # keep these two IRC ports normally open for BNC
> $IPF 50270 allow all from any to any 31337 in
> $IPF 50380 allow all from any to any 31337 out
> [snip -- more allowed ports]
> # deny and log everything
> $IPF 55000 deny log all from any to any
>
> -----
>
> Here's a dump of ipfw show, with some stuff cut out for space purposes
> (they're just denied DDoS IPs)
>
> [root@nub /etc]# ipfw show
> 00010 61124 16056802 allow ip from any to any via lo0
> 00020 0 0 deny ip from any to 127.0.0.0/8
> 00030 0 0 deny ip from 127.0.0.0/8 to any
> 00040 0 0 deny tcp from any to any frag
> 00050 0 0 check-state
> 00060 670616 455926379 allow tcp from any to any established
> 00070 16213 14071853 allow ip from any to any out keep-state
> [snip]
> 50220 468 22464 divert 8668 ip from any to 207.210.114.45
> dst-port 6667 via rl0
> 50230 0 0 divert 8668 ip from any to 207.210.114.45
> dst-port 8067 via rl0
> 50240 0 0 divert 8668 ip from any to 207.210.114.45
> dst-port 8068 via rl0
> 50250 0 0 divert 8668 ip from any to 207.210.114.45
> dst-port 6697 via rl0
> 50260 0 0 divert 8668 ip from any to 207.210.114.45
> dst-port 7000 via rl0
> 50270 1 60 allow ip from any to any dst-port 31337 in
> 54999 66 3991 allow icmp from any to any
> 55000 4364 343609 deny log logamount 100 ip from any to any
> 65535 29 4176 allow ip from any to any
>
> My natd.conf is as follows:
>
> [root@nub /etc]# cat natd.conf
> # Nub.Core NATd
> verbose
> alias_address 207.210.114.45
> log
> log_denied
> log_ipfw_denied
> pid_file /var/run/natd.pid
>
>
> ### IRC Redirect Ports
> # 6667


If I understand man natd


redirect_port tcp 72.20.28.202:6667 207.210.114.45:6667 207.210.114.45:6667
^^^^^^^^^^^^^
Trafic is comming from 72.65.73.23 - so the rule don't apply


[root@nub /etc]#
>
> And, as stated above, I am showing connection diverts to natd. When I
> run the following three tcpdumps:
>
> tcpdump -s 0 -w me_to_nat.pcap -vvv -i rl0 src host 72.65.73.23 and
> dst host 207.210.114.45 and dst port 6667
> tcpdump -s 0 -w nat_to_jail.pcap -vvv -i rl0 src host 72.20.28.202 and
> dst host 207.210.114.45 and dst port 6667
> tcpdump -s 0 -w jail_to_nat.pcap -vvv -i rl0 src host 207.210.114.45
> and dst host 72.20.28.202 and src port 6667
>
> Only the "me_to_nat.pcap" gets any data. The rest are 0 bytes. Example:
>
> -rw-r--r-- 1 root wheel 0 Mar 21 14:57 jail_to_nat.pcap
> -rw-r--r-- 1 root wheel 16384 Mar 21 15:24 me_to_nat.pcap
> -rw-r--r-- 1 root wheel 0 Mar 21 14:57 nat_to_jail.pcap
>
> So, can anyone diagnose and fix this? Thanks.
>
> (P.S.: I'm aware of the DNS methods of doing round-robin, but please
> keep that from this discussion. I need to port-forward round-robin,
> not whole DNS)
>


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