IP Route on Domain Controller

Posted on 2009-05-08
Medium Priority
Last Modified: 2013-11-16
Below is an Intrusion Prevention alert from our SonicWall Firewall. The intrusion is happening because the Source IP ( is not in our subnet range, so the firewall is freaking out thinking this is a "spoofed" IP. I have traced this IP address and MAC address to one of our connections (GB1000 Unplugged - network cable) on our DC. As you can see in the attached picture, it looks like it is disabled/unplugged, but I think there could be some routing involved.

I do not have enough knowledge in this area to figure out what is routing, so I provided the routing table below: The GB1000 connection in the picture has the ( I tried setting it to a static IP that would fall under our subnet, but it crashed the entire network connection, and I could no longer ping the server by its normal IP ( nor by the new static IP I tried to assign (

I have no idea what those other connections are, Virtual or Main. This is an older server and everything is working fine except this IP spoofing. My goal is to put things back to normal, where there is one connection "Local Area Connection". Any ideas are helpful and welcome, thank you.

Time: 05/07/2009 11:26:03
Priority: Alert
Category: Intrusion Prevention
Message: IP spoof dropped
Source:, 137, LAN
Destination:, 137, WAN, ws100098.bcr.local
Notes: MAC address: 00:02:b3:d8:bd:a2

This SonicWall is connected via site-to-site VPN to another office.
Local Network: /
Remote Network via site-to-site VPN: /
IPv4 Route Table
Interface List
0x1 ........................... MS TCP Loopback interface
0x10003 ...00 02 b3 d8 bd a2 ...... TEAM : Main
0x10004 ...00 1b 21 03 59 2e ...... Intel(R) PRO/1000 GT Desktop Adapter
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
     20     20     20     20      1     10     10     10     20     10      1      1
Default Gateway:
Persistent Routes:

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Question by:pzozulka
LVL 16

Accepted Solution

Blaz earned 600 total points
ID: 24340248 network is a network where Windows Automatic IP Addressing (APIPA) assigns addresses. If the computer is not able to connect to a DHCP server on boot it gets an address from this range.

It seems that some process on the server assigned itself the wrong IP of the server ( instead of and tried to browse the network (windows file sharing - port 137). As the network card was not connected the packet was routed through the other interface to your FW.

Try to disable the unneeded network card (GB1000 - right click -> disable).
LVL 10

Assisted Solution

lanboyo earned 600 total points
ID: 24350003
It looks like there is a network teamed interface and another interface that is configured for DHCP.  You can not assign the interface an address in the same subnet, this will confuse the server. configure interface teaming or disable the gigabit interface.

Author Comment

ID: 24351908
Can you provide further details about interface teaming. I have never heard of this before. This methodology is not frequently used right?

I would be very greatful if you can provide more material or links to good resources on this topic. I would like to know more.

Thank you.

Assisted Solution

qf3l3k earned 800 total points
ID: 24359093
Network interface teaming is in fact quite popular for servers with high level of data transmission to outside world.
This might be in regards to file servers or vmware servers.
In simple words it means that you have one network adapter with multiple ports (each 100Mb/s or more) or you have multiple adapters (same type and vendor) and you can consolidate all physical interfaces into one logical interface which will have IP address assigned.
Finally you can multiply bandwidth for your server by consolidating links. All adapters are plugged-in into same switch and vlan to allow all of them to communicate in the same IP segment.

More detailed explanation you can find here:

Assisted Solution

qf3l3k earned 800 total points
ID: 24359152
In addition you might want to check that link:

as it covers features of Intel adapters you have. The only question is if you will be able to team Desktop version of Intel adapter (from screenshot looks like there is something teamed aleady) as I never tried that.

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