[Mageia-discuss] Odd entry in log file

imnotpc imnotpc at Rock3d.net
Tue May 8 01:52:02 CEST 2012

On 05/07/2012 04:47 PM, Maarten Vanraes wrote:
> Op maandag 07 mei 2012 14:23:44 schreef Frank Griffin:
>> On 05/07/2012 06:45 AM, Frank Griffin wrote:
>>>> On 05/06/2012 09:15 PM, imnotpc wrote:
>>>> 1) Is eth0 the interface facing the internet ?
>>> No, this interface faces the LAN which has a subnet.
>> OK, so if eth0 has no outside internet access, you are correct in saying
>> that something in your network is doing this.
>>>> 2) Is the IP address assigned (currently) to you by
>>>> your ISP ?
>>> No, that IP returns to qe-in-f154.1e100.net which appears to be a
>>> server owned by Google.
>> Yes.  I thought maybe Google was your ISP.
>>>> 4) What does "traceroute" from the gateway give ?
>>> [root at Cedar1 /]# traceroute
>>> traceroute to (, 30 hops max, 60 byte packets
>>>   1  74-94-209-242-BusName-VA.hfc.comcastbusiness.net (
>>> 0.670 ms  1.372 ms  1.686 ms
>>>   2  * * *
>>> Well isn't that interesting. That Comcast IP is the address of the ISP
>>> gateway I use. Both of my firewall/gateway boxes that are logging
>>> martian packets are connected to similar Comcast routers. The routers
>>> are configured in bridge mode so the router DHCP service has no effect
>>> on my connection, but it might still be active on the router. Also
>>> each ISP router also has a wireless interface and that could still be
>>> active. My firewall doesn't block any private IPs coming from the
>>> Internet interface since the ISP routers would never forward them, so
>>> that explains how they get past the firewall.
>> No, I think traceroute doesn't special-case internal IP addresses.  Your
>> routing table is (correctly) set up to route traffic for anything other
>> than your known subnets to the external internet, and that's exactly
>> what traceroute is doing.  It's your ISP's job to discard internal
>> address packets, not yours.
>> But I think you're on to something with the ISP routers.  Is there some
>> reason you don't just run the cable from the cable modem to the external
>> NIC on the gateway PC ?  If you're willing to try that, and the martians
>> disappear, it's these routers.
>> Try going into configuration on these routers, and see what their DHCP
>> servers are set up for, and whether the 192.168.3 subnet appears
>> anywhere in there.  It's possible that one of your DHCP-using wireless
>> clients is getting an answer to its broadcast from these guys before
>> your internal router, and picking up a IP address from them.
> my martians are mostly from: hosts in subnet of my public IP, or internal
> ranges from modems, and mostly broadcasts or arp stuff.
> i think this stuff is likely someone in your ISP subnet that is
> doing bad natting and is trying to get out (much like you pinging 192.168.3.x
> which is going outside your public ip, that'll get martians on someone elses
> pc for instance

Since it seems to be coming in on the LAN facing interface, wouldn't it 
be more likely a bad configuration somewhere in my LAN? Everything seems 
to point to my cheap Netgear wireless router even though I just 
rechecked it and it's configured properly (to the best of my knowledge).


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