Accessing a Small Business Server (SBS) from Behind a SonicWall

03/26/2020 9 13625

DESCRIPTION:
Accessing a Small Business Server (SBS) from Behind a SonicWall

RESOLUTION:

Feature/Application:

In order to allow Internet users to access your Small Business Server located behind the SonicWall, it will be necessary to create the required firewall access rules and if you are using SonicOS Enhanced firmware then NAT policies also has to be created to permit and translate the traffic.

What services and ports should I allow on the firewall?

Microsoft Small Business Server 2003 includes many services, for example:

- MS Exchange, inbound email requires inbound SMTP traffic on TCP port 25 and Outlook Web Access requires inbound HTTPS traffic on TCP port 443;
- MS SQL, inbound SQL access requires inbound SQL traffic on TCP port 1433.

if you are not sure of the services and port numbers, the following weblinks should be helpful:

• List of components that are included in Windows Small Business Server 2003 for information on the protocols and port numbers used by SBS and
• Microsoft Windows Small Business Server 2003 with Service Pack 1 Getting Started guide - APPENDIX C Network Configuration Settings for additional considerations when using SBS behind a firewall.

After verifying the particular services and port numbers in SBS. The SonicWall should be configured to allow remote access to these services from the outside, appropriate NAT and Firewall Access Rules must be setup.

Procedure: 

SonicOS Enhanced:

The following example is for allowing SMTP, POP3 and IMAP service for the Private IP of the Mail Server (e.g.192.168.1.100) on LAN. You would follow the same steps for other services (like HTTP, HTTPS, FTP, Terminal, SSH, etc.). 

Step 1: Creating Address Objects

1. Select Network > Address Objects.
2. Click the Add a new address object button and enter the following into the fields:

• Name: MailServer Private 
• Zone Assignment: LAN
• Type: Host
• IP Address: 192.168.1.5

3. Click the OK button to complete creation of the new address object.

4. Click the Add a new address object button again and create another address object for Public IP of the server: 

Step 2: Create a Service Group

1. The Services page can be accessed either from Firewall > Services or Network > Services. 
2. Click Add Group.
3. Select individual services from the list in the left column. Click - > to add the services to the group.
4. To remove services from the group, select individual services from the list in right column. Click < - to remove the services.

5. When you are finished, click OK to add the group to Custom Services Groups.

Step 3: Creating NAT Policies

1. Select Network > NAT Policies.
2. Click the Add a new NAT Policy button and enter the following into the fields:

• Original Source: Any
• Translated Source: Original
• Original Destination: MailServer Public
• Translated Destination: MailServer Private
• Original Service: MailServer Services
• Translated Service: Original
• Inbound Interface: WAN
• Outbound Interface: Any
• Enable NAT Policy: Checked
• Create a reflexive policy: Checked 

3. Click the OK button to complete creation of the NAT policy.

Step 4: Creating Firewall Access Rules

1. Click Firewall --> Access Rules.
2. Select from WAN to LAN in the matrix.
3. Click Add a new entry and create the rule by entering the following into the fields:

• Action: Allow
• Service: MailServer Services
• Source: Any
• Destination: Mail server Public
• Allow Fragmented Packets: checked 

4. Under the Advanced tab, you can leave the “Inactivity Timeout in Minutes” at 30 minutes. Some protocols, such as Telnet, FTP, SSH, VNC and RDP can take advantage of longer timeouts where increased values like 45 or 60 minutes can be tried with caution in those cases. Longer timeout values will not help at all for HTTP or HTTPS.

5: Click OK.

SonicOS Standard:

If you want to allow access using the SonicWall's WAN IP address an Access Rule must be created or if you are using a separate Public IP address then you need to configure One-to-One NAT setup first, refer KBID 4464.

Creating an Allow access rule:

1. Login to the SonicWall Management Interface
2.Click Firewall --> Access Rules. Click Add. Create the rule by entering the following into the fields: 

- Action: Allow
- Service: (SBS server Services that you want to share, for example SMTP.)
- Source Ethernet: * (Asterisks * represent all IP addresses on that interface. This example allows the traffic from any address, which is appropriate for servers you want visible from the Internet and the LAN.)
- Source Address Range Begin: *
- Source Address Range End: *
- Destination Ethernet: LAN or DMZ (Select appropriate Interface where the server resides)
- Destination Address Range Begin: For inbound rules, such as the one in this example, you will almost always need to specify a single LAN or DMZ IP address representing the server.
- Destination Address Range End: Leave this field blank. 

3. Enable the “Allow Fragmented Packets” box. 

4. Under the Advanced tab, you can leave the “Inactivity Timeout in Minutes” at 30 minutes. Some protocols, such as Telnet, FTP, SSH, VNC and RDP can take advantage of longer timeouts where increased values like 45 or 60 minutes can be tried with caution in those cases. Longer timeout values will not help at all for HTTP or HTTPS.

5. Click OK.