# Airport Extreme and Port Forwarding



## blackoutspy (May 8, 2006)

Ok, so i have a windows box, a powerbook, and a linux server running in my room. I have some spacific ports forwarded to the linux server's ip. My problem is, the server's ip keeps switching from *.*.*.3 to *.*.*.4 So i have to keep changing my port forwarding addresses. Is there any way to make an IP address stay with a spacific machine and allow port forwarding?


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## nixgeek (May 8, 2006)

Are you saying that your Linux server is changing IPs?  Do you have it set for DHCP?  If so, I recommend that you set the IP for that particular machine to a static address.  Also, make sure that the Linux server's static IP which you assign to it is not within the scope (or range) of the DHCP leased addresses, otherwise you'll have IP conflicts on your network.


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## blackoutspy (May 9, 2006)

So while my airport is assigning IP's via DHCP to my windows and mac computers, i can have the linux just use a static ip?


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## jh2112 (May 9, 2006)

yes


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## nixgeek (May 9, 2006)

Yes you can, but you have to specify in the Airport basestation that it needs to exclude that particular IP from the scope.  Your best bet would be to state a range of IPs within a subnet while leaving another bunch available for static use.  For example:

*192.168.1.0 network address, 255.255.255.0 subnet mask*

*DHCP scope = 192.168.1.200--192.168.1.254* (192.168.1.255 is the broadcast address for the network which is why I didn't include it in the scope.)

This leaves *192.168.1.1--192.168.1.199* available for static use.


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## blackoutspy (May 9, 2006)

What information would i have to supply ifconfig with? Just the ip i've chosen and the mask? Or do i need to also set up something along the lines of next hop?


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## blackoutspy (May 9, 2006)

It seems that if i use a range of IP's instead of letting the router use them all, i am unable to use port forwarding. Whats that all about? Seems like theres no way for me to port forward and use static ip's.


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## nixgeek (May 9, 2006)

You should be able to still forward ports, but you'll only have to change the internal IP to which the port is being forwarded to from the Internet from within the basestation.  In other words, if it's set for port 22 to be forwarded to 192.168.1.3 and it should be to 192.168.1.10, then you would just have to change the IP listed to recieve forwarded requests on port 22.

As for the ethernet configuration on the Linux box, that depends on the distribution of Linux that you're running.  IF you provide that information, I can tell you how to do it.


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## blackoutspy (May 10, 2006)

Ok, i've looked into it further and my Airport will not allow me to forward ports if i use a range of IP's, i just don't knwo why its doing that. I went through some boxes from my recent move and it turns out i have a netgear router that has the ability to assign an IP to a mac address, which is just perfect. Thank you for your help.


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