Static IP/Port 4ward

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Hi all,

as im doing my N+, i just want some input for my own info really from you Network xperts.
Why would i need/want a static ip? mainly for port forwarding? And port forwarding, would i use that if say i wanted to send say downloads to a particular pc? Am i thinking right here or are there other scenarios for this, just inquisitive really.

Kat

 

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You would want one on servers, if the DHCP goes down and your server tries to renew its IP during that time it cant, oops no IP on the server now!

port forwarding basically means anything recieved on one IP on a certain port is sent to another PC
used mainly in NAT environments where the internal IP used by a server is not viewable from the internet

take this example

a Router has a public ip of 10.10.10.10 and an internal ip of 192.168.0.1

a server behind the router has an ip of 192.168.0.10

Ryan is on the internet and starts up a terminal server session, he only knows the public ip 10.10.10.10 and tries to connect to it, but alas the router does not run terminal server! so thats no good

however if i forward port 3389 to 192.168.0.10, any packet recieved by the router on that port it forwards to the server

so this time when Ryan connects to 10.10.10.10 on port 3389 the router sees the packet, and forwards it to the server, the server ofcourse DOES listen on port 3389 and a tcp session is sucessfuly established, two way communication now occurs
the server replys direct to Ryan but due to the NAT Ryan always sees it as originating from 10.10.10.10 anyway!

hope that basic description works!

---RDP to 10.10.10.10 -----------> .....(PF)....--------Port Forward to 192.168.0.10--------->
Ryan....................................... 10.10.10.10........................................................ 192.168.0.10
<------Packet from 10.10.10.10----....(NAT)....<-------------Packet from 192.168.0.10-----

 

Not sure what you mean by "send say downloads to a particular pc". Downloading is effectively a 'pull' operation by a client, so you wouldn't need a fixed IP.

The main reason for a fixed IP is to operate a server. Such beasts must have a 'known' location so they can be contactable by a client.

Of course, you could use a service such as DynDNS which gets round the problem fairly neatly.

Harry.

 

Thanks Ryan, explained as usual..

 

A public IP? <grin>

And yes - I did realize that was just used as an example....


Harry.

 

Thanks H,
i dont have experience with servers, so its uncommon to me. Ask q's-learn...
Kat

 

You'd want a static private IP in this situation. The router/gateway will have a public IP. So when the router receives external traffic on a specified port, it forwards to the internal computer on you LAN. And that's how a computer with a 192.168.x.x address can host just about anything on the internet. It's that simple. ;)

In any case, just wanted to point out that its really the internal client that needs to have a static IP. It would be perfectly fine to use a dynamic public IP in this scenario. Sounds a little backasswards, I know...

 

Kat, I presume you are talking about the IP address that is assigned to you by your ISP and why some ISP's offer a static address and some don't.

The only reason people want a static address is so that people can connect to them from the Internet.

A typical example would be if you were hosting your own web or email server.

As has been said it also makes remoting into your own network from the Internet using remote client software such as Windows Remote Desktop easier to establish.

You can use services such as dynamic DNS to get around the dynamic IP issue but that adds another layer of complexity into the scenario, hence it is not ideal.

 

It's a typically configuration for a cable modem user with a home router trying to host a online game of quake or download a movie using bittorrent. You usually have no control over whether you're assigned a static or dynamic public IP and, like I said before, it doesn't really matter anyway, either will work. It does matter if you use a static or dynamic internal IP however. ONLY a static internal IP will work.

Here's a screen capture from my home router as an example:

 

Crito what is Tribes? From what I can see it is an NZ pool of games servers. What's the buzz, tell me whats happening?

 

Jesus Christ Superstar lyrics aren't they?

 

There's no flys on you Baba

 

Tribes was one of the first team based FPS games out there, it rocked, and is now free if i recall correctly

there are follow ups but none as critically acclaimed as the original!

 

Nice one Pete, makes it clearer to me.

Kat