Interoperability with IBM Host Systems
Interoperability with IBM Host Systems |
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A firewall is a network security device that restricts access to network resources by allowing traffic only through specified port numbers. In many instances, the services of a firewall are provided in conjunction with a network route that bridges two network segments together.
If the SNA Server address is known, the client workstation configures the appropriate port and destination IP of the computer running SNA Server in the client software (1477 and 128.124.1.2, respectively, in Figure 10.25 below). Alternatively, the SNA Server–based computer's service port numbers can be changed to the port number requested by the client.
Figure 10.25 Using SNA Server with a Firewall
If the SNA Server address is not known, the SNA Server IP transport replaces the real destination IP address with the address of a firewall. The firewall then maps the connection request to the actual computer running SNA Server. This takes place when the transport opens a connection to an SNA Server–based computer for application sessions or a sponsor connection.
SNA Server supports firewalls primarily on TCP/IP networks. It is also possible to implement firewalls on IPX/SPX or Banyan VINES networks. Consult your network documentation for information about configuring a firewall in your specific installation.
