ADDER CATx User Manual

Also see for AdderView CATx AVX4016: User guide

Contents

ADDER CATx User Manual Manual pdf 100 page image

 99PortsIf you accept the analogy of IP addresses being rather like telephone numbers,then think of ports as extension numbers. In a company of any size, yougenerally wouldn’t expect the accounts department to share the same telephonewith the technical department. Although their calls may all be related to thesame company, they concern very different aspects of that company.It is the same with IP network connections. Although you have only one networklink into your computer and only one IP address (phone number), you areprobably performing many different tasks through that one link, often at thesame time. Thus, when you browse the web your outgoing requests and theincoming information are all channelled through port 80. When you send anemail, it travels through port 25 and when you transfer files you are, withoutknowing it, using port 20.At the “border crossing” between the wider Internet and every local networkattached to it, there is a router that is usually combined with a firewall. One ofits main tasks is to direct incoming traffic to the correct place within its localnetwork. A key piece of information to help it do this is the port number:Security issues with portsThe settings of port numbers become important when the AdderView CATx IPis situated behind a network firewall. In order for a remote VNC viewer or webbrowser to make contact with your AdderView CATx IP, it is necessary for thefirewall to allow communication through a particular numbered port to occur.One specific function of firewalls is to restrict access to ports in order to preventmalicious attackers using them as a route into your network. Every new port thatis opened offers a new possibility for hackers and so the number of accessibleports is purposefully kept to a minimum. In such cases, it may be advantageousto change one or both AdderView CATx IP ports to use the same number. Theother alternative is to place the AdderView CATx IP unit outside the firewall andtake full advantage of its secure operation features – see Networking issues fordetails.IMPORTANT: The correct configuration of routers and firewalls requiresadvanced networking skills and intimate knowledge of the particular network.Adder Technology cannot provide specific advice on how to configure yournetwork devices and strongly recommend that such tasks are carried out by aqualified professional.AdderView CATx IP hasthe local IP address:192.168.0.3User with VNC viewer accessesIP address: 129.7.1.10 (thisautomatically uses port 5900).Router/firewall address: 129.7.1.10Router is programmed to send port 5900VNC traffic to local address 192.168.0.3and port 80 web traffic to local address192.168.0.42User accesses the companywebsite at: 129.7.1.10 (thisautomatically uses port 80).Web server has the localIP address: 192.168.0.42