Re: SQLNet through a firewall

SQL*Net (Net8 too) over TCP/IP works like this:

The client program asks SQL*Net to establish a connection. SQL*Net looks up the connect string in TNSNAME.ORA, and finds the IP address and port to use. Then it sends a connect request to the listener. LISTENER.ORA configures the listener to listen on a particular port for requests to connect certain databases. When it gets a request, it starts a shadow process for the user and connects that process to the proper database. It hands the process a randomly selected port for the continuing connection to use, and informs SQL*Net on the client. Then the listener gets out of the way, and resumes listening for the next connection. Notice that the connection is no longer using the port on which it was started.

So you have to configure the firewall so that it will allow traffic on any port, PROVIDED that the original connection was on the listener's port. This is a fairly common situation on TCP/IP, and you should be able to find a good example of it in your firewall's manual. I think either ftp or telnet work this way, but I forget which. Received on Tue Nov 09 1999 - 21:31:54 CST