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TICKET ARCHIVE -> Port Forwarding
Eristokrat - Jan 14, 2006 - 10:31 pm
Ok, so I'm totally at sea here. I know almost nothing about networks, so I thought it would be fun to try setting up a bit torrent client and see what I learn. I've learned that I know almost nothing about networks. Apparently I am able to initiate connections but not able to recieve remote connections. I'm told the solution to this lies in forwarding the port my client uses and that this probably has something to do with using a wireless router to access the internet. How does one forward a port? What information do I need and where do I get it? Thanks for your help.
E.
E.
marcusr - Jan 15, 2006 - 3:26 am
Hello,
A quick summary of networking to start - all computers have an IP address, and when you want to communicate with a computer, you send network packets to its address. You can think of the IP address as the computer's phone number. When the packet arrives at the computer, it needs to know which program running on the computer should deal with it. Each service running on a computer, e.g. a web server, a mail server, a bittorrent server, will have its own port - e.g. the web server has port 80, the bittorrent server usually has 6881. You can think of port numbers as extensions, so when you dial the computer, you dial the phone number to connect to the computer, and then use the port number as an extension number to get put through to the service you want.
If your computer was connected directly to the internet, other bittorrent clients could just connect to your IP address and then speak to the bittorrent program running on your machine. However, when you have a router between you and the internet, you use something called Network Address Translation (NAT). This means that the router has your public IP address, and listens for communications. Your computer has a private IP address (one which noone can speak to on the internet).
When you connect to a web site for example, your computer starts the connection, but instead of communicating directly to the web site server, it connect to the NAT router. The router then makes the connection for you to the web server. The web server replies to the NAT router, and the router passes the reply back to your computer. The advantages of this are that the NAT router can share its one public IP address with lots of your computers - it maps the private IP addresses of your computers to the one public one.
Here's the key to port forwarding though - it only passes through traffic from the outside that is a response to a connection you started. This acts as a strong firewall - noone on the outside can initiate a connection to any of your computers on the inside, keeping you safe. However, it also means that bittorrent clients can't connect to your machine.
So, routers have something called port forwarding. You log into the router, and look for the NAT section, and you can add port forwarding rules. You tell the router that if a packet arrives on the bittorrent port, it should forward it on to a machine on the inside.
Can you tell me what make of wireless router you have? What I can tell you generally though is to log into your router, and look for the NAT section. The port numbers you want to forward are 6881, 6882 and 6883. The IP address is the IP address of your computer - you can find this on the Mac by going to System Preferences, Network, choosing the active connection and pressing the configure button, and then choosing the TCP/IP tab. You will need to set up a port forward rule for each port individually.
Hopefully that explains what is happening and the information you need - let me know if I can help you out more with the specific router you have.
Marcus
A quick summary of networking to start - all computers have an IP address, and when you want to communicate with a computer, you send network packets to its address. You can think of the IP address as the computer's phone number. When the packet arrives at the computer, it needs to know which program running on the computer should deal with it. Each service running on a computer, e.g. a web server, a mail server, a bittorrent server, will have its own port - e.g. the web server has port 80, the bittorrent server usually has 6881. You can think of port numbers as extensions, so when you dial the computer, you dial the phone number to connect to the computer, and then use the port number as an extension number to get put through to the service you want.
If your computer was connected directly to the internet, other bittorrent clients could just connect to your IP address and then speak to the bittorrent program running on your machine. However, when you have a router between you and the internet, you use something called Network Address Translation (NAT). This means that the router has your public IP address, and listens for communications. Your computer has a private IP address (one which noone can speak to on the internet).
When you connect to a web site for example, your computer starts the connection, but instead of communicating directly to the web site server, it connect to the NAT router. The router then makes the connection for you to the web server. The web server replies to the NAT router, and the router passes the reply back to your computer. The advantages of this are that the NAT router can share its one public IP address with lots of your computers - it maps the private IP addresses of your computers to the one public one.
Here's the key to port forwarding though - it only passes through traffic from the outside that is a response to a connection you started. This acts as a strong firewall - noone on the outside can initiate a connection to any of your computers on the inside, keeping you safe. However, it also means that bittorrent clients can't connect to your machine.
So, routers have something called port forwarding. You log into the router, and look for the NAT section, and you can add port forwarding rules. You tell the router that if a packet arrives on the bittorrent port, it should forward it on to a machine on the inside.
Can you tell me what make of wireless router you have? What I can tell you generally though is to log into your router, and look for the NAT section. The port numbers you want to forward are 6881, 6882 and 6883. The IP address is the IP address of your computer - you can find this on the Mac by going to System Preferences, Network, choosing the active connection and pressing the configure button, and then choosing the TCP/IP tab. You will need to set up a port forward rule for each port individually.
Hopefully that explains what is happening and the information you need - let me know if I can help you out more with the specific router you have.
Marcus
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