TCP Resets

External Since: Jul 26, 2006 Posts: 6

Hello all !

I posted this in the AD forum yesterday, but got no responses, so I'm
going to post here too....sorry for the dual post...but we see this most
often from our AD Domain Controllers.

What we are seeing is a large number of TCP resets (see below) coming
from our AD Domain Controllers, talking to clients. We kind of expect
this to be a FIN-ACK instead of a reset. Any thoughts? Is this
“normal”? If so, why?

BTW...Looks like is it's doing Kerberos over TCP

SUMMARY: TCP: Ack Seq#=55975276 Ack#=535452271 Win=0
Frame 5448 at 27.570707013: (60 Bytes)
AD63:88 --> P8675309:1449
Network Error:TCP Reset
Sequence Number = 55975276 (0 byte)
Acknowledgement Number = 535452271
Window Size = 0

Thanks !
Geoff

External Since: Jul 26, 2006 Posts: 6

Thanks for the info....I'll check, and post back

TAce Fekay [MVP] wrote:
> In news:%23eBPufLsGHA.4896@TK2MSFTNGP03.phx.gbl,
> Geoff <nigeltufnel123 DeleteThis @gmail.com> stated, which I commented on below:
>> Hello all !
>>
>> I posted this in the AD forum yesterday, but got no responses, so I'm
>> going to post here too....sorry for the dual post...but we see this
>> most often from our AD Domain Controllers.
>>
>> What we are seeing is a large number of TCP resets (see below) coming
>> from our AD Domain Controllers, talking to clients. We kind of expect
>> this to be a FIN-ACK instead of a reset. Any thoughts? Is this
>> “normal”? If so, why?
>>
>> BTW...Looks like is it's doing Kerberos over TCP
>>
>> SUMMARY: TCP: Ack Seq#=55975276 Ack#=535452271 Win=0
>> Frame 5448 at 27.570707013: (60 Bytes)
>> AD63:88 --> P8675309:1449
>> Network Error:TCP Reset
>> Sequence Number = 55975276 (0 byte)
>> Acknowledgement Number = 535452271
>> Window Size = 0
>>
>>
>> Thanks !
>> Geoff
>
> I can'
> t say if this is normal or not, but it doesn't appear correct, since you
> mentioned Kerberos using TCP. I know Kerberos uses UDP 88, so I can't answer
> you there, and I have not captured traffic to view this, unless someone else
> can chime in on that.
>
> Do any of the packets show Kerberos using UDP first, then try TCP? Is this
> client to domain controller traffic across a WAN? Any 3rd party spyware, or
> antivirus with security features installed?
>
> Do any of the routers (assuming going across a router) have the MTUs altered
> or going across a NAT device with multiple internal interfaces? Either one
> will affect LDAP traffic. LDAP requires the MTU to be 1500, and if a NAT has
> multiple internal interfaces, to disable H.323