Port Forwarding

[bunker]

Using an old reliable Linksys BEFSR41...

I set up port forwarding for bittorrent to go to my main machine.

Let's say I want to start using it on another machine. Can I add another entry in the port forwarding table, using the same port/protocol, and have it pointing to a different machine or will it automatically send all traffic on that port to the first box?

 

[unmerited]

My understanding is that you can only forward a port or multiple ports to only 1 computer at a time.


unmerited

 

[Payton]

Will the linksys even let you setup a port forwarding rule with the same port more than once? Kind of defeats the purpose of that feature

 

[bunker]

Originally posted by: Payton
Will the linksys even let you setup a port forwarding rule with the same port more than once? Kind of defeats the purpose of that feature

Haven't even tried, I was just curious. It makes sense to me. At work, I'm a server admin (not network 😉) and I have several machines that I've had to ask to have port 1433 opened for sql communication. I was wondering if my router was similar to the firewall here. I can have the same port open to multiple machines: (consider the / and \ as paths through the firewall on port 1433)

...........WebServer
.........../...............\
Database1.....Database2

 

[Nothinman]

I'm a server admin (not network ) and I have several machines that I've had to ask to have port 1433 opened for sql communication. I was wondering if my router was similar to the firewall here. I can have the same port open to multiple machines: (consider the / and \ as paths through the firewall on port 1433)

But think about that for a second. When you connect to the SQL server behind the firewall what IP do you use? The one for the SQL server and not the firewall, right? That's because that IP is being routed without modification through the firewall.

That's not how your personal Internet connection works. You have 1 public IP address that the world can connect to, on your DSL/Cable router, but several machines behind it all masquerading as that one IP. This is called NAT or Network Address Translation. Now when a connection to port 1433 comes into that router how does it know where to forward the connection? You have to tell it and if you tell it multiple addresses it'll get confused, if it even lets you do that.

If your firewall at work was doing NAT you would have the same problem.

 

[JackMDS]

OK we are talking about the Internet coming in.

The IP address that its arrives with is external. The Router (if possible) has port 25000 open toward internal IP 192.168.1.1 and 192.168.1.2 how it would know were it suppose to go?

However if you are thinking about Internal traffic (not from the out Side) the port opening through the NAT is not relevant.

:sun:

 

[bunker]

Okay, all makes sense to me now. That's why I just run the servers and not the networking equipment 🙂.

 

[Nothinman]

That's why I just run the servers and not the networking equipment

No offense, but it scares me that people are allowed to run networked services without a basic understanding of how the network under their devices works.

Actually what scares me more is that developers are allowed, and able, to write apps that use TCP/IP without any clue how the protocols work. We have programs written by developers that had no idea what a port was so they just picked years that they liked for one reason or another.

 

[bunker]

Originally posted by: Nothinman

That's why I just run the servers and not the networking equipment

No offense, but it scares me that people are allowed to run networked services without a basic understanding of how the network under their devices works.

Actually what scares me more is that developers are allowed, and able, to write apps that use TCP/IP without any clue how the protocols work. We have programs written by developers that had no idea what a port was so they just picked years that they liked for one reason or another.

Heh, I knew someone was going to say that, no offense taken. I run the web servers, I know enough about networking to do my job. I understand the majority of it, I just have no control over the routers, firewalls and switches so I guess I don't care to know if my communications problems are taking place on layer 2 or 3 of the OSI model. Like I said, that's what we have a NOC for 🙂. I learned that stuff about 10 years ago, never used it, so I've forgotten it all.

In rereading my original post I guess I do come off as a clueless noob, but really, I'm not that bad!