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Archive for November, 2010

Forefront TMG 2010 RDP suddenly not working anymore

November 24, 2010 6 comments

A weird thing happenend today with our TMG 2010 box. We powered down our server to add some extra memory to get some better performance. After powering on we could not RDP into the server anymore. After we logged on to the console we did a netstat -ano | findstr “3389” but it show no results. The firewall log shows:

Closed Connection TMG-FE 23-11-2010 17:48:44
Log type: Firewall service
Status: A connection was abortively closed after one of the peers sent an RST packet.(0x80074e21 FWX_E_ABORTIVE_SHUTDOWN)
Rule: [System] Allow remote management from selected computers using Terminal Server
Source: Internal (10.200.0.99:50813)
Destination: Local Host (10.204.100.100:3389)
Protocol: RDP (Terminal Services)
Additional information
Number of bytes sent: 52 Number of bytes received: 40
Processing time: 0ms Original Client IP: 10.200.0.99

After playing around we found a fix:

start an MMC and add the RD session host configuration snap-in.
goto the connection section and look at the properties of the RDP-tcp protocol
goto the adapter tab..
enter listening on all adapters and close
click on disable connection
click on enable connection
goto the adapter tab
enter listening on internal interface
click on disable connection
click on enable connection

enter in a dos box
netstat -ano | findstr “3389”

now its listening again and we could RDP again….weird fix but it works for me.

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Forefront TMG and Windows Live Essentials 2011

November 15, 2010 1 comment

Since the release of Windows Live Essentials 2011 some reports came to my attention that MSN will not work in combination with Forefront TMG. It seems that it only occurs if you use access rules with authentication included.  To get this working we need to create an URL set with 3 enries:

http://www.sqm.microsoft.com/sqm/messenger/sqmserver.dll/*

http://ssw.live.com/uploaddata.aspx/*

http://*.gateway.messenger.hotmail.com/*

Now create a new access rule without authentication that included this URL set. Place the newly created rule above the rule with authentication. Now you are done and able to use Windows Live Essentials 2011.

Using Non-Web Server Publishing rules with a route relationship on Forefront TMG

November 8, 2010 Leave a comment

If you read my articles about installing and configuring Forefront TMG Back to Back solutions (here and here) you might have wondered why I did not configure a publishing rule that points to the backend exchange 2003 server. Instead I created an access rule between the Barracuda and the backend exchange 2003 server. Normally you will allways use access rules if there is a route relationship between te networks and publishing rules if there is a NAT relationship. Its one of the TMG’s best kept secrets that you can actually use publishing rules when using a route relationship between networks. You might wonder why does OWA even work in our scenario without implementing some special things? as you can see we used an Exchange Web Client Access rule. The answer to this is the following:

The Web Listener used for Web publishing will always include the TMG Web Proxy Filter. Because an application proxy mechanism such as the Web Proxy Filter creates a completely new connection between TMG and the published server, and because the default for Web Publishing rules is to “Use the ISA computer IP address” when creating these connection. Thus, TMG appears to perform NAT on the traffic between the client and server, because it creates sockets for its configured IP Addresses even if there is a route relationship between the networks.

So it actually uses a NAT relationship between the client and the server. Thats why it works out of the box.
Back to our problem. Regarding the Barracuda: By default you only have the option to deliver mail to a specific IP Address and it does not know the route to the backend exchange server because you cannot create static rules by default. So we want to deliver mail traffic to 10.6.0.2 (secondary interface of the TMG-BE).Lets create the publishing rule on the TMG-BE:

Rule Name: Publish mail traffic from Barracuda to Exchange 2003 Backend (choose non-web publishing rule)
Rule number : place on top
Rule Action : Allow
Protocols : SMTP Custom port 25 inbound
From : Barracuda
To : Exchange 2003 Back-End (10.4.30.30)
Network Listener IP Address : Perimeter Interface  IP : 10.6.0.2
User Sets : All Users
Make sure you enable : requests appear from original client

Well if you look at the TMG firewall log you will see its not working at all:

mmm… that seems weird. Lets check if the TMG is actually listening on port 25 on the 10.6.0.2 ip address:

Doesn’t seem that way because it returns nothing. Lets check with netsh tmg command set (replacement for ISA’s fwengmon command):

Nope nothing there as well. As said before the TMG firewall will not listen on a specific IP with port 25 if there is a route relationship bewtween the networks. Solution: We need to create a NAT relationship between the Barracuda and the exchange 2003 backend.

Goto the Forefront TMG – Networking – Network Rules tab
Create a new network rules called Exchange backend to perimeter
Source network : Exchange backend
Destination network : Perimeter
Relationship : NAT
Rule order: place above internal to perimeter route rule

Important : Disable en enable your publishing rule (created above) otherwise it will not work !! Lets take a look at the logging again:

and if the listener is working now:

Yep.. it seems that everything is working now.

Install & Configure Forefront TMG Back to Back solution Part 2

November 5, 2010 2 comments

This article is the second and last part of my series about Installing and configuring Forefront TMG back to Back. In the first one I explained the network setup, network relationships, the TMG backend and TMG Frontend installations and some simple firewall rules. In the second part we will be configuring OWA for exchange 2003, web publishing rules, and incoming and outgoing SMTP mail.

Configuring OWA for exchange 2003 with FBA

Forms-based authentication(FBA) is one of the cool features that is included in the TMG software. The FBA enables the TMG’s capablility to enable the OWA logon form on the TMG firewall instead of enabling it on the exchange 2003 box. It enables you to force authentication on the TMG firewall before packets are forwared to the exchange 2003 box. If you want to create a fancy FBA logon page then check my post here.

requirements:

  • FBA should be disabled on the exchange 2003 box.
  • The TMG firewall that needs FBA needs to be joined to the domain. (thus we use the TMG-BE)
  • A certificate with your companies webmail address should reside on the exchange 2003 and TMG-BE boxes. (the certificate should include something like webmail.test.com)
  • A new forward lookup zone should be configured on the DC1 server named test.com. Create a new A record called webmail.test.com that points to 10.4.20.20
  • At your provider you should create a DNS record that points webmail.test.com to ISP IP2

We want to make OWA dummy proof. Experience shows that users often forget the default URL https://webmail.test.com/Exchange . Users should be able to type the URL with HTTP or HTTPS and with or without /Exchange. So lets create the rules on the TMG-FE first :

  • Rule Name : Publish Outlook Webmail Apps (OWA) – HTTP    (choose non-web publishing rule)
  • Rule Number : 1
  • Rule action : Allow
  • Server IP : 10.6.0.2 (secondary ip on the TMG-BE external interface)
  • Create New Protocol :  HTTP Server on Port 80 inbound
  • Listener IP Address : External Interface IP : ISP IP2 only
  • Make sure you enable : requests appear from original client
  • Rule Name : Publish Outlook Webmail Apps (OWA) – HTTPS    (choose non-web publishing rule)
  • Rule Number : 2
  • Server IP : 10.6.0.2
  • Protocol : HTTPS Server
  • Listener IP Address : External Interface IP : ISP IP2 only
  • Make sure you enable : requests appear from original client

Create the rules on the TMG-BE

  • Name : Publish Outlook Webmail Apps (OWA) (Choose Exchange Client Access rule)
  • Rule Number : 1
  • Exchange version : exchange 2003
  • Mail services : OWA
  • Rule action : Allow
  • Publishing Type : single website
  • Server Connection Security : SSL
  • Internal Sitename : webmail.test.com
  • Ip Address : 10.4.20.20
  • Request appear to come from TMG
  • Public name details : webmail.test.com
  • Create New Listener
  • Web Listener Name : HTTP(S) OWA
  • Client Connection Security : SSL (HTTPS en HTTP)
  • Enable redirection http to https
  • Web Listener IP Address : Perimeter Interface IP : 10.6.0.2 only
  • Certificate : webmail.test.com
  • Authentication Settings : HTML Form authentication
  • Validation : Windows (active directory)
  • SSO : disabled
  • Authentication Delegation : basic authentication
  • User Set : All authenticated users group
  • Edit the newly reated rule ang go to the paths tab
  • Add the following path : (beware the Capital E of Exchange and the \ at the end)

  • on the TO tab make sure you enable : requests  from Forefront TMG

Outlook Web Access should work just fine by now. Just test it by accessing it remotely.

Configuring webserver access internally and remotely

Users need to access the webserver from outside the network but also from inside the corporate network. To accomplish this you need to config the following:

  • in the new forward lookup zone create a new A record called http://www.test.com that points to 10.6.10.10
  • At your provider you should create a DNS record that points http://www.test.com to ISP IP1
  • The default gateway of the webserver points to the internal interface of the TMG-FE. So the webserver does not know the route to VLAN1, VLAN2, VLAN3, VLAN4 and VLAN5. Therefore you need static routes on the webserver to access those networks.

Create the rule on the TMG-FE first :

  • Rule Name ; Publish HTTP traffic to the webserver (choose web publishing rule)
  • Rule Number : 2
  • Rule action : Allow
  • Publishing Type : single website
  • Server Connection Security : NON-SSL
  • Internal Sitename : http://www.test.com
  • Ip Address : 10.6.10.10
  • Path : /*
  • Public Name : http://www.test.com
  • Path : /*
  • Create New Listener
  • Web Listener Name : HTTP WWW
  • Client Connection Security : NON-SSL
  • Web Listener IP Address : External Interface IP : ISP IP1 only
  • Authentication Settings : None
  • Authentication Delegation : No delegation, client cannot authenticate
  • User Sets : All Users

Create the rule on the TMG-BE :

  • Name : Allow HTTP(s), RDP, FTP traffic to the webserver (choose access rule)
  • Rule Number : place above normal http traffic rule
  • Rule Action : Allow
  • Protocols : HTTP, HTTPS, RDP, FTP
  • From : Internal Networks
  • To : Webserver
  • User Sets : All Users

Now you are done !. We achieved access to the webserver from the outside world and from the internal corporate network.

Configuring inbound and outbound mail (SMTP)

Since we are hosting our mail solution internally we need to achieve inbound and outbound mail traffic.

requirement:

  • At your provider you should create a MX DNS record that points mail.test.com to ISP IP3
  • The default gateway of the barracuda points to the internal interface of the TMG-FE. Therefore it does not know the route to the 10.4.x.x network. We need to add a static route on the Barracuda. If you have a 600 model or higher you can add the static route right away. However if you have a 400 model that option is not available. If you contact barracuda support they will enable that option for you.

Create the rule on the TMG-FE first :

  • Name : Publish mail traffic to antispam firewall (mail publishing rule)
  • Rule Number : place on top
  • Access Type : Server to server communication SMTP,NNTP
  • Services : SMTP (custom SMTP server protocol port 25 inbound with SMTP filter disabled)
  • From : Anywhere
  • Server IP Address : 10.6.20.20 (the barracuda)
  • Network Listener IP Address : External Interface  IP : ISP IP3 only
  • Make sure you enable : requests appear from original client

Create the rule on the TMG-BE :

  • Name : Allow mail traffic to internal LAN (choose access rule)
  • Rule Number : place on top
  • Rule Action : Allow
  • Protocols : SMTP
  • From : Barracuda
  • To : Exchange 2003 Back-End
  • User Sets : All Users
  • Name : Allow mail traffic to outside (choose access rule)
  • Rule Number : place on top
  • Rule Action : Allow
  • Protocols : SMTP
  • From : Exchange 2003 Back-End
  • To : external
  • User Sets : All Users

This concludes my 2 part series about Installing and configuring Forefront TMG Back to Back solution. I hope its usefull for you and feel free to comment.

Install & Configure Forefront TMG Back to Back solution Part 1

November 4, 2010 1 comment

This week we installed and configured an Forefront TMG back to back solution in our school. In this article I am explaining on how to implement this in your company. It will be a 2 part article. In the first one I will explain the network setup, network relationships, the TMG backend and TMG Frontend installations and some simple firewall rules. In the second part we will be configuring OWA for exchange 2003, web publishing rules, and incoming and outgoing SMTP mail. For this article we are going to use the following network setup:

This is a simple setup that is used in many companies and universities. The Backend TMG firewall (TMG-BE) will be installed and joined to the domain (test.local) and the Frontend TMG firewall (TMG-FE) will be installed and joined to a workgroup (WORKGROUP). Our company website is hosted on the webserver and will be available for the ouside world. The Barracuda Appliance will listen to incoming SMTP mail and will be used for Spam filtering and virus checking. After this check the mail will be forwarded to the Exchange 2003 Back-End. Outlook Web Access (OWA) will be made available as well.

TMG network relationships

An important issue to understand is how network relationships work in an Back to Back solution. Dr. Thomas W. Shinder made some great articles about this and i highly recommend reading them. They can be found here. For our network setup we use the following network relationships:

As you can see we will use an ROUTE relation ship between the internal network and the DMZ network (configured on the TMG-BE). And we will use an NAT relationship between the DMZ and External segment (configured on the TMG-FE). Its also important to understand that there is a NAT relationship between the internal network and the external network (configured on the TMG-BE). For ROUTE relationships you need to use access rules (from inside to outside and from oputside to inside). For NAT relationships you need to use access rules (from inside to outside) and publishing rules (from outside to inside). As said normally…… Its not widely known that you can use publising rules on a route relationship as well. We are going to use one when we are going to configure OWA.

Its also important to understand whats internal and external regarding to the TMG firewalls. For the TMG-BE it looks like this:

The TMG-BE will see VLAN1, VLAN2, VLAN3, VLAN4, VLAN5 as the INTERNAL network. it will see VLAN6 as the PERIMETER network and VLAN7 as the EXTERNAL network. For the TMG-FE it will look like this:

The TMG-FE will see VLAN1, VLAN2, VLAN3, VLAN4, VLAN5 and VLAN6 as the INTERNAL network and VLAN7 as the EXTERNAL network. For our article we will use the following ip adressing scheme:

Installing the TMG-BE

 Before you install TMG 2010 on your machine make sure that:

  • You renamed you internal NIC to something like Internal and you external NIC to something like DMZ.
  • You entered all appropriate information in all NICs (according to the ip addressing scheme)
  • You joined the TMG-BE to the domain
  • Increase performance by changing the value at HKEY_LOCAL_MACHINE\System\CurrentControlSet\NetBT\Parameters. Change NodeType to value 2 (REG_DWORD)
  • Update system with latest service packs and updates

Ok. lets start the TMG 2010 Back-End installation:

  • Start the TMG 2010 installation and choose to run the Preparation Tool
  • Select Forefront TMG services and Management en wait untill everything is complete
  • The Forefront TMG installation will start
  • Enter your username, company name and serial number
  • Enter the installation path to your liking
  • Now we need to enter the internal network for the TMG-BE. Remember we spoke of this before. We need to enter all subnet ips from VLAN1, VLAN2, VLAN3, VLAN4, VLAN5.

  • Start TMG-KB981324-AMD64-ENU.MSP to install  TMG 2010 Service Pack 1.
  • Start TMG-KB2288910-AMD64-ENU.exe to install Update 1 for Service Pack 1.
  • Start the TMG MMC and select Configure network settings
  • Select BACK FIREWALL and the INTERNAL adapter as Local Area Network
  • In the same window we need to add some static routes. The internal interface of the TMG-BE does not have a default gateway configured. We need to tell the TMG-BE how to reach VLAN1, VLAN2, VLAN3 and VLAN4. The gateway configured on the core switch will be 10.5.0.1. Lets add 4 static routes:

  • Select the DMZ interface as the PERIMETER network adapter and choose a private (ROUTE) relationship
  • Select configure system settings and leave everything as default
  • Select define deployment options and enter licenses if applicable
  • Close the getting started wizard

Installing TMG-FE

Before you install TMG 2010 on your machine make sure that:

  • You renamed you internal NIC to something like DMZ and you external NIC to something like INTERNET.
  • You entered all appropriate information in all NICs (according to the ip addressing scheme)
  • You joined the TMG-FE to a workgroup
  • Increase performance by changing the value at HKEY_LOCAL_MACHINE\System\CurrentControlSet\NetBT\Parameters. Change NodeType to value 2 (REG_DWORD)
  • Update system with latest service packs and updates

Ok. lets start the TMG 2010 Front-End installation:

  • Start the TMG 2010 installation and choose to run the Preparation Tool
  • Select Forefront TMG services and Management en wait untill everything is complete
  • The Forefront TMG installation will start
  • Enter your username, company name and serial number
  • Enter the installation path to your liking
  • Now we need to enter the internal network for the TMG-FE. We need to enter all subnet ips from VLAN1, VLAN2, VLAN3, VLAN4, VLAN5 and VLAN6.

  • Start TMG-KB981324-AMD64-ENU.MSP to install  TMG 2010 Service Pack 1.
  • Start TMG-KB2288910-AMD64-ENU.exe to install Update 1 for Service Pack 1.
  • Start the TMG MMC and select Configure network settings
  • Select EDGE FIREWALL and the DMZ adapter as Local Area Network
  • In the same window we need to add some static routes. The internal interface of the TMG-FE does not have a default gateway configured. We need to tell the TMG-FE how to reach VLAN1, VLAN2, VLAN3, VLAN4 and VLAN5. The gateway configured for the routes will be the external interface of the TMG-BE (10.6.0.1) Lets add 5 static routes:

  • Choose the INTERNET networkadapter for the ISP connection
  • Select configure system settings and leave everything as default
  • Select define deployment options and enter licenses if applicable
  • Close the getting started wizard

Configuring the TMG-BE

  • Start the TMG MMC and goto Forefront TMG (TMG-BE) – Networking – Networks tab
  • Richtmouseclick on the internal networks and choose properties – choose the domains tab
  • In the domain names box add: *.test.local
  • Choose the webbrowser tab and change the following:
  • Enable Bypass proxy for webservers in this network
  • Enable directly access computers specified in the domains tab
  • Enable directly access computers specified in the addresses tab
  • Choose the Autodiscovery tab and enable publish automatic discovery
  • Configure your DNS and DHCP server for WPAD – read here
  • Lets create some firewall rules to allow DNS, HTTP, HTTPS and FTP traffic.
  • Goto Forefront TMG (TMG-BE) – Firewall Policy – Create access rule

Create the following rules:

  • Rule Name : Allow DNS traffic from DC1
  • Rule Number : 1
  • Protocols : DNS
  • From : DC1
  • To : External
  • User Sets : All users
  • Rule Name : Allow HTTP, HTTPS, FTP traffic
  • Rule number : 2
  • Protocols : HTTP, HTTPS, FTP
  • From : Internal Network
  • To : External Network
  • User Sets : All authenticated users

Configuring the TMG-FE

  • Start the TMG MMC and goto Forefront TMG (TMG-FE) – Intrusion Prevention System – Behavorial Intrusion Detection tab – choose configure Flood Mitigation settings – IP exceptions tab
  • Since there is a NAT relationship between the internal network and external network on the TMG-BE the source ip will be changed to the TMG-BE external interface. So when the packet arrives at the TMG-FE internal interface it will see alot of traffic coming from one ip address. Therefore we must add the external interface from the TMG-BE to the ip exceptions tab or else the TMG-FE will drop traffic.
  • Goto Forefront TMG (TMG-FE) – Firewall Policy – Create access rule

Create the following rule:

  • Rule Name : Allow all traffic from TMG-BE
  • Rule number : 1
  • Protocols : All protocols
  • From : TMG-BE (external interface ip) 
  • To : External Network
  • User Sets : All users

Now you can test your created rules by starting a webbrowser session from the DC1. In part 2 of this article we are going to configure OWA for exchange 2003, web publishing rules, and incoming and outgoing SMTP mail. Feel free to comment on this article.

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