[isalist] Re: Mac Connection Problem
- From: Jim Harrison <Jim@xxxxxxxxxxxx>
- To: "isalist@xxxxxxxxxxxxx" <isalist@xxxxxxxxxxxxx>
- Date: Sun, 6 Nov 2011 01:44:58 +0000
As my mother used to say; "better a smartass than a dumbass..."
:)
From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On
Behalf Of Steven Comeau
Sent: Saturday, November 05, 2011 1:27 PM
To: isalist@xxxxxxxxxxxxx
Subject: [isalist] Re: Mac Connection Problem
Whew...I can get to sleep now.
Steve Comeau
Associate Director of IT Rutgers Athletics
83 Rockafeller Road
Piscataway, NJ 08854
732-445-7802
732-445-4623 (fax)
www.scarletknights.com<http://www.scarletknights.com>
[Description: rutgers100px.gif]
[Description:
C:\Users\scomeau\AppData\Roaming\Microsoft\Signatures\Steve21.jpg]
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>
[mailto:isalist-bounce@xxxxxxxxxxxxx]<mailto:[mailto:isalist-bounce@xxxxxxxxxxxxx]>
On Behalf Of Jim Harrison
Sent: Saturday, November 05, 2011 3:15 PM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Mac Connection Problem
..and a month later, we have the answer...
First off, public apologies to Rob for the terrible delay in responding...
Second, based on the data Rob so kindly trusted me with (posted on my FB page
for anyone who wants it :)), it's clear that his Linux firewall isn't
maintaining TCP state.
Initiation packets flow to the file server just fine, but response packets get
routed directly back to the MAC instead of through TMG where they should have
gone.
The reason TMG logs a reject is because the MAC sees the response traffic from
the file server IP address using the wrong MAC address and TCP SEQ# and sends a
RST to TMG (default route, remember?).
Because the RST uses a SEQ# that TMG has not seen in any conversation with the
MAC, it closes the connection and logs "someone is being stupid" (don't you
wish I could have written the TMG error messages?).
I know there are some critical details missing, but I'll leave it to Rob as to
whether he wants those made public.
Jim
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>
[mailto:isalist-bounce@xxxxxxxxxxxxx]<mailto:[mailto:isalist-bounce@xxxxxxxxxxxxx]>
On Behalf Of Jim Harrison
Sent: Tuesday, October 04, 2011 3:00 PM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Mac Connection Problem
You're already allowing it.
Unless you have other TMG logs for those hosts and that traffic, what you're
indicating is not TMG blocking valid traffic.
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>
[mailto:isalist-bounce@xxxxxxxxxxxxx]<mailto:[mailto:isalist-bounce@xxxxxxxxxxxxx]>
On Behalf Of Rob Moore
Sent: Tuesday, October 04, 2011 8:18 AM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Mac Connection Problem
How do I allow SMB, given that all the remote subnets are configured as
Internal?
Rob
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>
[mailto:isalist-bounce@xxxxxxxxxxxxx]<mailto:[mailto:isalist-bounce@xxxxxxxxxxxxx]>
On Behalf Of Steve Moffat
Sent: Saturday, October 01, 2011 6:45 AM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Mac Connection Problem
Are you allowing SMB or AFP?
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>
[mailto:isalist-bounce@xxxxxxxxxxxxx]<mailto:[mailto:isalist-bounce@xxxxxxxxxxxxx]>
On Behalf Of Rob Moore
Sent: Friday, September 30, 2011 6:32 PM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Mac Connection Problem
I've continued to think about this issue and try various other things. Oddly, I
can do other things from the Macs to the remote servers, such as ping them or
open an RDP session to them. I see ping and RDP traffic allowed on the TMG
console. But I can't open the equivalent of an Explorer window to the remote
servers from a Mac. The TMG server seems to be blocking just that one sort of
traffic. So how can I tell TMG not to block it? It doesn't SEEM reasonable to
me (I'm NOT a networking expert) that the problem is the sort of network
problem Jim described if all kinds of traffic but one can successfully pass.
Thanks,
Rob
From: Rob Moore
Sent: Friday, September 30, 2011 10:28 AM
To: 'isalist@xxxxxxxxxxxxx'
Subject: RE: Mac Connection Problem
If this is true, though, wouldn't it affect all clients at a given site? PCs
work just fine used from the same locations. It's only the Macs that are
affected.
I guess your last point would explain why the internal-internal rule didn't do
anything. :)
Thanks,
Rob
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>
[mailto:isalist-bounce@xxxxxxxxxxxxx]<mailto:[mailto:isalist-bounce@xxxxxxxxxxxxx]>
On Behalf Of Jim Harrison
Sent: Friday, September 30, 2011 9:22 AM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Re: Mac Connection Problem
Rob,
Typically, communication failure coupled with those log entries indicates some
sort of split routing or a response path that is different from the initial
traffic path.
There are a couple of ways this can occur:
1. The Linux firewall isn't doing source-NAT and the internal target host
uses TMG as the default route
2. The VPN client at the Linux firewall get assigned an IP address that
is not specified in the target host routing table and the target host uses TMG
as the default route
In both cases, the initial TCP:SYN will be received by the internal host from
the Linux FW and its TCP:SYN_ACK response will be sent to TMG; resulting in
traffic rejection and the log entries you see.
TMG is a stateful firewall and as such, will reject "first seen" TCP traffic
that fails to abide by RFC-793.
BTW, I hope your "internal-internal" rule is only for testing, as it's
generally non-functional. Unless TMG is actually separating different subnet
with individual NICS and both networks have been defined as "internal" to TMG,
this is a wasted rule.
From: isalist-bounce@xxxxxxxxxxxxx<mailto:isalist-bounce@xxxxxxxxxxxxx>
[mailto:isalist-bounce@xxxxxxxxxxxxx]<mailto:[mailto:isalist-bounce@xxxxxxxxxxxxx]>
On Behalf Of Rob Moore
Sent: Thursday, September 29, 2011 8:51 AM
To: isalist@xxxxxxxxxxxxx<mailto:isalist@xxxxxxxxxxxxx>
Subject: [isalist] Mac Connection Problem
Hello Everyone-
I'm using TMG Standard standalone running on Windows 2008 R2 SP1.
We're a mostly Windows organization, though since our new CEO is a Mac-o-phile,
Macs are becoming more common. Today I found a problem. First let me give you
some background. Our headquarters is here in Philadelphia. We have 30 remote
offices, each with a Linux-based firewall that also is a VPN endpoint. There is
another Linux-based firewall on our network here that all the remote ones VPN
to. (It's not ideal, but it works and is more affordable for us-a
non-profit-than what we'd like to have: a bunch of TMG boxes.)
Anyway, Macs here in Philly can connect to our local Windows (2003 or
2008)-based servers without issue. But when we try to connect a Mac here in
Philly to a remote Windows server share (the traffic traveling over our
Linux-based VPN), our TMG server appears to be blocking the traffic. (FWIW, our
Windows-based clients can connect to those remote servers without issue.) Also,
if a remote Mac connects to our VPN (PPTP, to a server here in Philly), they
also can't connect to our remote servers.
The Macs in question are running the latest Mac OSX (10.7.1).
The remote networks are defined on the TMG server as part of the Internal
network.
There is a TMG rule allowing internal-to-internal traffic (at least I think
that's what it's doing). The rule is Allow; All Outbound Traffic; From:
Internal, Local Host; To: Internal, Local Host; All Users. It doesn't seem to
be applied here, though, based on the error message.
I tried creating a specific rule just for this traffic, and put it at the top
of the rules (just below my "Block Slammer" rule). That rule is Allow;
Microsoft CIFS (TCP) and NetBios Session; From Internal, Local Host; To:
Internal, Local Host; All Users. I get the same error as above, though,
indicating no rule is applied.
Anyway, we get a lot of these two errors coming through the TMG console when
the Mac is trying to connect:
Client IP
Destination IP
Destination Port
Protocol
Action
Overridden Rule
NIS Scan Result
NIS Signature
NIS Application Protocol
Rule
Result Code
HTTP Status Code
Client Username
Source Network
Destination Network
172.17.201.39
192.168.9.2
445
Microsoft CIFS (TCP)
Denied Connection
-
None - see Result Code
0xc0040017 FWX_E_TCP_NOT_SYN_PACKET_DROPPED
Internal
Internal
172.17.201.39
192.168.9.2
139
NetBios Session
Denied Connection
-
None - see Result Code
0xc0040017 FWX_E_TCP_NOT_SYN_PACKET_DROPPED
Internal
Internal
Any help with what's going on? How can I stop TMG from blocking the Microsoft
CIFS and NetBios protocols over this internal connection? How did I incorrectly
configure my rule?
Thanks,
Rob
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Rob Moore
Network Manager
215-241-7870
Helpdesk: 800-500-AFSC
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