Using Old Versions of OpenVPN or OpenSSL

By default, Tunnelblick uses the latest version of OpenVPN with the latest version of OpenSSL to connect VPNs.

Using other versions of OpenVPN and OpenSSL is not recommended because they may contain security vulnerabilities.

However, using other versions of OpenVPN and OpenSSL is sometimes necessary to connect to VPN servers that use old versions of OpenVPN and/or OpenSSL, including servers imbedded in equipment such as routers and firewalls that are sometimes not upgraded regularly. To enable such connections, Tunnelblick usually includes several older versions of OpenVPN and OpenSSL. In some situations, Tunnelblick automatically uses one of these older versions to connect. In other situations, a close examination of error messages will allow the user to manually choose an older version of OpenVPN and OpenSSL.

If you use a VPN that is administered by someone else, there is little you can do other than notify your network and/or VPN administrators that they should update their software or equipment. When they have done so, check that Tunnelblick is using the latest or default version.

If you are administer your own VPN, you should keep the VPN server up-to-date with the latest versions of OpenVPN and OpenSSL, and make sure Tunnelblick is using the latest or default version.

To check what version of OpenVPN and OpenSSL Tunnelblick is using for a particular VPN configuration, select the configuration on the "Configurations" panel of Tunnelblick's "VPN Details" window, then examine or change the "OpenVPN version" in the "Settings" tab.