If the internet connectivity indicator in the Slink Agent System Preferences pane (highlighted below) is amber, Slink Agent could not configure your broadband router and establish inbound internet connectivity:

Reasons why the problem may occur

The most common reasons why Slink may fail to configure your broadband router are:

• Your home Mac is not connected to the internet
• UPnP (or NAT-PMP) is disabled on your broadband router
• Port conflict on your broadband router
• Double network address translation (double NAT)
• Manual port mapping has been configured and port is closed
• Home Mac is directly connected to the internet, but port 22 is blocked

Resolution 1: Your home Mac is not connected to the internet

If your Mac is not connected to the internet, the following message is shown in the Slink Agent System Preferences pane:

Resolution:

• Ensure your home Mac is connected to the internet.
• Test your internet connectivity by visiting a common site, such a Google.

Resolution 2: UPnP (or NAT-PMP) is disabled on your broadband router

If the Slink Agent fails to automatically configure your broadband router, the following message is shown in the Slink Agent System Preferences pane:

This means that your broadband router could not be configured by Slink Agent using UPnP or NAT-PMP.

Resolution:

There are two common causes for this:

• Your broadband router does not support UPnP or NAT-PMP
  Apple products, such as the Airport, support NAT-PMP and most broadband routers have supported UPnP since 2001. Please confirm support for one of these protocols with the manufacturer of your broadband router. If your broadband router does not support UPnP or NAT-PMP, you must configure your broadband router manually.
• UPnP or NAT-PMP is disabled on your broadband router
  Please consult the manual for your broadband router and enable UPnP or NAT-PMP.

Resolution 3: port conflict on your broadband router

If the Slink Agent fails to automatically configure your broadband router due to a port conflict, the following message is shown in the Slink Agent System Preferences pane:

By default, Slink attempts to configure external port 443 for use by Slink. If this port has already been configured on your broadband router by another application, or if another copy of Slink Agent running on another Mac in your home network has already configured it, the router configuration may fail.

Resolution:

You can resolve this problems in one of two ways:

• Disable the conflicting port mapping
  If a manual port mapping conflicts with your Slink Agent port setting, you can manually remove it from your broadband router’s configuration. If an automatic port mapping conflicts with your Slink Agent port setting, you need to reconfigure or quit the application that automatically configured that mapping.
• Change Slink Agent external port
  Change the Slink Agent external port to another port that does not have a conflict with another port mapping.

Resolution 4: double network address translation (double NAT)

If the Slink Agent fails to automatically configure your broadband router due to double network address translation, the following message is shown in the Slink Agent System Preferences pane:

This means that your computer is located behind two (or more) or routers that perform NAT (Network Address Translation). Having multiple NAT routers between your computer and the internet is generally a bad idea, and a sign of a configuration issue with your home network.

Resolution:

You can resolve this problems in one of two ways:

• Ensure that only your broadband router perform NAT
  Disable NAT on the routers that are located behind your broadband router. (Please note, this may require you to add routes on your broadband router.) Alternatively, configure the routers to operate in switching/bridging mode instead of routing mode. This is the preferred approach.
• Configure port mapping on your broadband router and on all NAT routers located behind it.
  Configure port mapping on your broadband router and on all NAT routers located behind it. This is a complex and error-prone approach, and is not recommended.

Resolution 5: Manual port mapping has been configured and port is closed

If the Slink Agent has been configured for manual port mapping and the external port is closed, the following message is shown in the Slink Agent System Preferences pane:

This means one of the following:

• Your broadband router has not been configured correctly for Slink. (Or that you have not had time to do it yet!)
• The external port is blocked by your internet service provider. Some internet service provides block certain ports below 1024.
• The Mac OS X firewall on your home Mac is blocking the port
• A third party security package on your home Mac, such as VirusBarrier or Little Snitch, is blocking the port.

Resolution:

You can resolve this problems in the following ways:

• Enable automatic configuration of your broadband router
  Set “Configure broadband gateway” to “Automatically” in the Slink Agent System Preferences pane, and Slink will automatically configure your broadband router for you. This is the preferred option.
• Ensure that your broadband router is configured correctly
  Follow the instructions in the Configuring your broadband router manually article to ensure that your broadband router is configured correctly.
• Change Slink Agent external port
  Change the Slink Agent external port to another port that is not blocked by your internet service provider.
• Disable the Mac OS X firewall
  Disable the Mac OS X firewall to check if it is causing the problem. If it is, enable it again, but ensure that Remote Login (SSH) is an allowed service.
• Disable the third party security package
  Disable the third party security package to check if it is causing the problem. If it is, enable it again, but ensure that Remote Login (SSH) is an allowed service.

Resolution 6: Home Mac is directly connected to the internet and port 22 is blocked

If your home Mac is directly connected to the internet with a public IP address and port 22 (SSH) is blocked, the following message is shown in the Slink Agent System Preferences pane:

When you are directly connected to the internet, Slink Agent must use the Remote Login port, normally port 22, for all communication.

Port 22 can be blocked for the following reasons:

• A firewall or router between your home Mac and the internet blocks port 22.
• The Mac OS X firewall on your home Mac is blocking the port.
• A third party security package on your home Mac, such as VirusBarrier or Little Snitch, is blocking the port.

Resolution:

You can resolve this problems in the following ways:

• Ensure that any firewall or router between your home computer and the internet does not block port 22
  If that is the case, the firewall or router must be reconfigured to not block port 22.
• Disable the Mac OS X firewall
  Disable the Mac OS X firewall to check if it is causing the problem. If it is, enable it again, but ensure that Remote Login (SSH) is an allowed service.
• Disable the third party security package
  Disable the third party security package to check if it is causing the problem. If it is, enable it again, but ensure that Remote Login (SSH) is an allowed service.