As a matter of interest, does your wireless router have a built-in Firewall? (Most recent routers do) If so and you are interested in blocking off P2P traffic at the router, my following advice should help:
Most routers that offer firewall features allow you to set up rules to allow or block specific content. If all you use is web browsing, FTP file transfer and E-mail access, then it is fairly straight forward to block out other applications. Each application type uses its own port, for example Internet browsing uses port 80, E-mail uses ports 25 and 110 and so on.
Normally the simplest way to block an application is to block its port number. However Kazaa overcomes this by using different port numbers. In fact the only way block or severely restrict Kazaaâ€™s performance is to block every port but the ports the applications you use connect with. With most other P2P software, you simply block the port the P2P software connects out on and the application will no longer connect.
Go into your routerâ€™s web interface through your web browser and go to the Firewall page. On D-Link Wireless routers, click on the â€˜Advancedâ€™ tab and click on â€˜Firewallâ€™ down the left column. It will probably show a list of current default rules.
Firewalls work by taking a piece of data, going through the rules one by one starting from the top of the list and if it meets a rule that matches the dataâ€™s port, it decides on what to do with the data based on the rule and does not perform any rule checks on this data. For example if the outgoing data has a port SMTP (Outgoing E-mail), the firewall looks for either a rule specifically on SMTP, source& destination or a range of ports that includes SMTP. If it finds one and the source is LAN (internal network) and the destination is WAN (Outside network, i.e. the Internet), then if the rule is â€˜Allowâ€™ the firewall allows the data pass and does not check the next rule. If the rule is â€˜Denyâ€™, the firewall discards the data without checking any further rules.
As Iâ€™m not sure what Internet applications you use, so Iâ€™ll assume the basic: Internet â€“ Port 80, E-mail â€“ Ports 25 & 110, FTP â€“ 20 & 21 and DNS â€“ 53.
Now, add the following rules:
If the firewall automatically shows blank entry fields for entering a new rule, then follow these steps and click â€˜Applyâ€™ after each step (such as D-Link routers). Otherwise, click on â€˜Add Ruleâ€™ (varies from router to router) and click â€˜Saveâ€™ or â€˜Applyâ€™ (also varies from router to router).
For the source, select â€˜LANâ€™ and for the destination select â€˜WANâ€™. Enter a â€˜*â€™ in both â€˜startâ€™ fields. Enter port 80 into the TCP start and end range boxes. Finally click on â€˜Applyâ€™ or â€˜Saveâ€™ to add this rule. Tick the box â€˜Allowâ€™ and if there is an option to enable the rule, tick the box â€˜Enabledâ€™. Repeat this sequence of steps over & over again to add the same rule for ports 20 - 21, 25, 53 and 110.
Finally we wish to block all other traffic, so again add another rule selecting â€˜LANâ€™ for the source, â€˜WANâ€™ for the destination, put a â€˜â€™ in both â€˜startâ€™ fields, but put â€˜â€™ in the TCP start range and, tick the box â€˜Denyâ€™ and tick the box beside â€˜Enabledâ€™ to enable the rule (if available). Now, move this â€˜Denyâ€™ rule down so that it is listed below all the above application ports. To do this, click on â€˜Move downâ€™ or the down arrow beside the new Deny rule. Repeat this until all the applications allow ports are above his. For D-Link routers, click the down arrow on the highlighted rule until this highlight covers the bottom application rule you allowed (likely the HTTP allow rule). Then click â€˜Applyâ€™.
If after you perform these steps and Kazaa still works as it done before, then there is either some â€˜allow allâ€™ rule taking precedence or the firewall on the router is not enabled. Generally if Kazaa manages to get out using the few application ports, it generally operates quite poorly as very few Kazaa supernodes run on port 80 or other common application ports from what I recall.
The following screen shot should show what your rules will look like. This shot was taken from a D-Link wireless router, so your screen layout may vary:
Note that the last three rules for this D-Link router are default and cannot be removed. Even though the very bottom rule is effectively the direct opposite of the 4th last Deny rule, the router will reach the 4th last 'Deny' first since firewalls work in a top-down approach.