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] On Behalf Of Jim Harrison Sent: Friday, September 30, 2011 9:22 AM To: 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