Pál Csányi wrote:
> ---------- Forwarded message ----------
> From: Pál Csányi <[EMAIL PROTECTED]>
> Date: 2007.08.02. 17:52
> Subject: Re: [Shorewall-users] exim4 behind a firewall
> To: Tom Eastep <[EMAIL PROTECTED]>
> 
> 
> 2007/8/2, Tom Eastep <[EMAIL PROTECTED]>:
>> Pál Csányi wrote:
> 
>>> DNAT         net   loc:192.168.1.100               tcp   80
>> Didn't you want port 25 there rather than 80?
> 
> No, this is for my web server, and this works fine, the port is open, and
> answers for the requests. Try http://csanyi-pal.info

The reason that I asked is that the post that I was replying to had NO DNAT
rule for smtp.

> It's in hungarian language yet.
> 
>>> The port 25 is still closed from the internet. :(
>>>

> rules:
> DNAT         net   loc:192.168.1.10-192.168.1.98:25  tcp  25   -
> 212.200.112.79

Why are you specifying a range of IP addresses? Are you running 89 smtp
servers? You should only be specifying the IP address of the system where
exim is running (192.168.1.98).

> 
> I tried now with masq:
> ppp0                    eth1            212.200.112.79
> 
> No success.

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> 
> I red Shorewall FAQs 1a.
> -----------------------------------------
> - I'm trying to test from inside my firewall:
> http://wigwam.sztaki.hu/varazslatok/port_teszt.shtml
> It's in hungarian. You must to click on the button:
> WIGWAM - gyors tűzfalteszt
> 
> that is in english: fast firewall test
> 
> This site scan your ports and find out whether is the port open and
> answer for the queries.
> 
> - on my desktop behind firewall:
> ifconfig
> eth1      Link encap:Ethernet  HWaddr **:**:**:**:**:**
>           inet addr:192.168.1.98  Bcast:192.168.1.255  Mask:255.255.255.0
> eth1 get his IP address with dhcp-client from the firewall.
> route -n
> Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
> 192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
> 0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth1
> 
> - I ask from my ISP that, that he opens for me the ports 80 & 25, and
> he was opened these ports for me.
> 
> - I'm running Debian GNU/Linux Etch
> 
> I red Shorewall FAQs 1b.
> -----------------------------------------
> iptables -t nat -Z
> With: http://wigwam.sztaki.hu/varazslatok/tamadas.shtml
> I attack my own port 25:
> Szimulált támadás szabadon választott porton:
> PORT: 25 TÁMADJ MEG!
> 
> This is a simulated attacking for my port 25.
> 
> sudo shorewall show nat
> ...................................
> Shorewall-3.2.6 NAT Table at debian-tuzfal - 2007. aug.  2.,
> csütörtök, 17.38.52 CEST
> 
> Counters reset 2007. aug.  2., csütörtök, 16.58.56 CEST
> 
> Chain net_dnat (1 references)
>  pkts bytes target     prot opt in     out     source
> destination
>     0     0 DNAT       tcp  --  *      *       0.0.0.0/0
> 212.200.112.79      tcp dpt:25 to:192.168.1.10-192.168.1.98:25
> ..................................

> Because I must use pptp-linux to connect to my ISP, for that I use the
> ppp0 interface. The simulated attack can use only the ppp0 interface
> to connect to port 25.
> - My DNAT rule doesn't match the connection request in some other way.

We are still not seeing enough here to tell what is going on (other than
your DNAT rule is clearly wrong).

> How can I use tcpdump to further diagnose the problem?

        tcpdump -ni ppp0 port 25

Then try to connect to port 25 from the net.

-Tom
-- 
Tom Eastep    \ Nothing is foolproof to a sufficiently talented fool
Shoreline,     \ http://shorewall.net
Washington USA  \ [EMAIL PROTECTED]
PGP Public Key   \ https://lists.shorewall.net/teastep.pgp.key

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