We're doing NAT.  We just don't need additional "NAT rules" according to
the Untangle definition of them.  We should have just been using the
system-created rules and not creating additional rules of our own.


On Thu, Aug 7, 2014 at 3:01 PM, Paul Boniol <[email protected]> wrote:

> Something will be needing to do NAT since you are using 192.168.
> addresses.  Whether that's your firewall or your ISP connection(s).
>
> Paul
>
>
> On Thu, Aug 7, 2014 at 2:49 PM, Chris McQuistion <[email protected]>
> wrote:
>
>> Mystery solved!
>>
>> I called Untangle and got some help from them.  (I'm paying for this
>> thing, so I ought to get some tech support, right?)
>>
>> My port forwarding and everything was pretty straightforward and nothing
>> wrong there.
>>
>> Untangle has the ability to create static routes, but they also have "NAT
>> rules" where you can set up something very similar to a static route, but
>> it also re-writes the packets on the way out of the network to strip out
>> any internal IP information.  We had "NAT rules" set up and didn't really
>> need them.  Once the "NAT rule" was disabled, /var/log/messages starting
>> showing the correct external IP address when I would connect in, from the
>> off-site server.
>>
>> It's weird that it only affected our RHEL 5 server and none of the
>> others.  The NAT rule only re-writes outgoing packets and not incoming
>> packets, so the Untangle guy couldn't quite figure out why it would affect
>> an incoming SSH connection like this, but the fact is that it did and the
>> NAT rules really weren't needed.
>>
>> Chris
>>
>>
>> On Thu, Aug 7, 2014 at 1:32 PM, Sabuj Pattanayek <[email protected]>
>> wrote:
>>
>>> the interesting part is that it only seems to be happening on his RHEL5
>>> system and not on the other ones.
>>>
>>>
>>> On Thu, Aug 7, 2014 at 11:48 AM, Tilghman Lesher <[email protected]>
>>> wrote:
>>>
>>>> None of those packages would affect how packets are logged.  At this
>>>> point, I'd do a tcpdump on the external interface on that particular
>>>> server, then pull up the dump in Wireshark.  That should tell you
>>>> whether the packets are being rewritten incorrectly by the firewall or
>>>> if the server is simply doing something strange.  You shouldn't have
>>>> to look any further than the IP header to verify the
>>>> source/destination address.
>>>>
>>>> On Thu, Aug 7, 2014 at 11:27 AM, Chris McQuistion
>>>> <[email protected]> wrote:
>>>> > Interesting thought.
>>>> >
>>>> > The firewall rules are the same for this server as all the other
>>>> servers and
>>>> > none of the other servers are showing this anomaly in their logs.
>>>> >
>>>> > I went ahead and deleted the rule, then recreated it, then tested
>>>> again.
>>>> > Same results.
>>>> >
>>>> > The day that I started getting these weird entries was the first day
>>>> that
>>>> > server was logged into from offsite and right after installing some
>>>> yum
>>>> > updates.  I looked through the Logwatch emails and these yum updates
>>>> > correspond to that same day.  Any chance one of these could change
>>>> the way
>>>> > that this information is being logged?  I can tail /var/log/secure
>>>> and watch
>>>> > it log the wrong IP address when I login from home.
>>>> >
>>>> > Packages Updated:
>>>> >     nss-3.15.3-7.el5_10.i386
>>>> >     httpd-manual-2.2.3-87.el5_10.x86_64
>>>> >     1:mod_ssl-2.2.3-87.el5_10.x86_64
>>>> >     nspr-4.10.6-1.el5_10.i386
>>>> >     nss-tools-3.15.3-7.el5_10.x86_64
>>>> >     firefox-24.7.0-1.el5_10.i386
>>>> >     nss-3.15.3-7.el5_10.x86_64
>>>> >     httpd-2.2.3-87.el5_10.x86_64
>>>> >     firefox-24.7.0-1.el5_10.x86_64
>>>> >     nspr-4.10.6-1.el5_10.x86_64
>>>> >
>>>> >
>>>> >
>>>> >
>>>> > On Thu, Aug 7, 2014 at 10:42 AM, Tilghman Lesher <
>>>> [email protected]>
>>>> > wrote:
>>>> >>
>>>> >> On Wed, Aug 6, 2014 at 3:20 PM, Chris McQuistion
>>>> >> <[email protected]> wrote:
>>>> >> > This is a weird problem.
>>>> >> >
>>>> >> > I get the daily logwatch emails from our various servers and one
>>>> of the
>>>> >> > things that I eyeball on a regular basis is the "Users logging in
>>>> >> > through
>>>> >> > sshd".  I like to make sure that I don't see any logins from IP
>>>> >> > addresses
>>>> >> > that I don't recognize (as well as failed login attempts.)
>>>> >> >
>>>> >> > We changed our firewall about a week and a half ago, over to
>>>> Untangle.
>>>> >> > This
>>>> >> > has had no negative affect on any of the usual behavior except for
>>>> one
>>>> >> > of
>>>> >> > our servers, a database server running RHEL 5.X (64 bit, fully up
>>>> to
>>>> >> > date.)
>>>> >> >
>>>> >> > On this one system, I'm now seeing the following line in it's daily
>>>> >> > Logwatch
>>>> >> > email:
>>>> >> >
>>>> >> > 192.168.1.254 (firewall.watkins.edu): 2 times
>>>> >> >
>>>> >> > That IP address is the firewall, itself.  The firewall is NOT
>>>> actually
>>>> >> > logging into this server.  My Linux box at home is logging in via
>>>> SSH,
>>>> >> > every
>>>> >> > day, to run backups.  In the past, and with every other server
>>>> that I
>>>> >> > remotely backup via SSH, every day, the Logwatch email reflects
>>>> the IP
>>>> >> > address of my cable modem at home.
>>>> >> >
>>>> >> > In this one case, this server shows 192.168.1.254 (the firewall)
>>>> as the
>>>> >> > source IP address instead of the "real" source IP address.
>>>> >> >
>>>> >> > Port forwarding to this server is set up exactly the same way as
>>>> all the
>>>> >> > other servers.  The backup program I'm running at home (dirvish)
>>>> >> > connects to
>>>> >> > this server, just like the other servers.
>>>> >> >
>>>> >> > The only variable that has changed is the firewall and possibly
>>>> some
>>>> >> > recently-run yum updates.  The only unique thing about this
>>>> server, is
>>>> >> > that
>>>> >> > it is our only RHEL 5 server.  We also have a RHEL 6 server and
>>>> several
>>>> >> > CentOS 5/6 servers.
>>>> >> >
>>>> >> > Any ideas?
>>>> >>
>>>> >> I suspect a difference in how your firewall is set up to forward
>>>> those
>>>> >> packets.  I'd look at the underlying iptables commands, not the
>>>> >> frontend information.  It sounds like the firewall is rewriting the
>>>> >> source address on those packets.
>>>> >>
>>>> >> --
>>>> >> Tilghman
>>>> >>
>>>> >> --
>>>> >> --
>>>>
>>>> --
>>>> Tilghman
>>>>
>>>
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