[rhizopod]

I've got the Tivo HD connected via wired ethernet to my Linksys WRT54G. It's getting an IP address via DHCP, 192.168.1.105. On another computer, which has a static IP address of 192.168.1.102, I run Azureus. In my router I have port forwarding enabled for 192.168.1.102 (only) for Azureus. However, after installing the Tivo HD, I routinely get errors from Azureus saying that my Tivo (192.168.1.105) has reserved the port in question. Can anyone help me understand what's going on? It would appear that Tivo is somehow overriding the port forward in my router setup, and has "stolen" my Azureus port forward from my other computer (as well as potentially many others) for its own use! Anyone have any ideas? Or know of any utilities I can use to monitor which ports on what machines are getting forwarded to the gateway on my network?

 

[coreyt]

Sounds like you have UPnP turned on. This lets the tivo grab ports as needed.


Just configure Azerus to use another port range and you should be fine.

 

[Saturn]

Or turn off uPnP in your router. Some routers have a status screen to view UPnP routes, most don't.

 

[gbrown]

There are several music services and games that require uPnP to be enabled. But if you dont use them, I highly suggest you disable the feature in your Router. It is a security nighmare. A statefull firewall doesn't allow random port opening from outside the firewall. With uPnP enabled, this feature is bypassed allowing outsiders to open ports.

 

[rainwater]

First off, you should never use a static IP that is in the range of your DHCP clients. Check to see how many DHCP clients you have and what the starting IP address is. Then make sure your static ip computer using a ip outside of that range.

 

[rhizopod]

First off, you should never use a static IP that is in the range of your DHCP clients. Check to see how many DHCP clients you have and what the starting IP address is. Then make sure your static ip computer using a ip outside of that range.

My static and dynamic IP address ranges do not overlap. I have effectively reserved 192.168.1.101-104 for static IPs by starting my DHCP range at 192.168.1.105.

Thanks for the tips, guys. I will try them out when I get home.

 

[lessd]

First off, you should never use a static IP that is in the range of your DHCP clients. Check to see how many DHCP clients you have and what the starting IP address is. Then make sure your static ip computer using a ip outside of that range.

Why ? I do that, never had a problem (I know of), I have static and DHCP intermingled never knew one should not do that.

 

[rhizopod]

What's going to happen when your DHCP server tries to assign an already existing static IP address to a new client?

 

[DocNo]

Why ? I do that, never had a problem (I know of), I have static and DHCP intermingled never knew one should not do that.

Lets say you have a DHCP pool with addresses 1-10

You statically assign computer C an address of 5

You then get a five other devices on your network - your DHCP server will hand out the new fifth device the address of 5 - since it thinks it has that address available to it. After all, you told it it did when you set up your DHCP pool. So now you have a conflict, and neither Computer C nor the new device will work.

So, if your DHCP pool is addresses 1-10, set up your first static address at 11. Then you will ensure you have no conflicts. Or reduce the size of the pool to 1-8 and set the first static address as 9 - either way you want to keep your DHCP pool and your static addresses separate to prevent conflicts.

 

[vman41]

You then get a five other devices on your network - your DHCP server will hand out the new fifth device the address of 5 - since it thinks it has that address available to it. After all, you told it it did when you set up your DHCP pool. So now you have a conflict, and neither Computer C nor the new device will work.

Some DHCP servers will do a quick ping of the prospective address before they hand it out. It's still a good idea to keep your statically assigned addresses separate from the DHCP pool addresses.

 

[Chimpware]

What's going to happen when your DHCP server tries to assign an already existing static IP address to a new client?

When an IP is assigned by the DHCP server it always checks "is this IP out there already?" using standard arp or in some cases ping. If that IP currently exists it simply doesn't use it and assigns another.

Note that static IP user must be online ands reply. If that user is NOT online and DHCP assigns that address then yes, the static user will have issues when it tries to use that address - it will flash a bunch of errors and NOT get on the network until something is changed.

I agree though no reason to pollute the DHCP pool.

 

[doormat]

I havent had this problem with Azureus and my TiVo HD. I have a WRT54GL with the linksys firmware and uPNP on. Though my WHS box is having a hard time getting uPNP working lately (pre-TiVo HD). I may have to go and assign those ports manually.

 

[DocNo]

When an IP is assigned by the DHCP server it always checks "is this IP out there already?" using standard arp or in some cases ping. If that IP currently exists it simply doesn't use it and assigns another.

Not all do this. I wouldn't rely on a linksys router, for example, to do that.

 

[lessd]

Lets say you have a DHCP pool with addresses 1-10

You statically assign computer C an address of 5

You then get a five other devices on your network - your DHCP server will hand out the new fifth device the address of 5 - since it thinks it has that address available to it. After all, you told it it did when you set up your DHCP pool. So now you have a conflict, and neither Computer C nor the new device will work.

So, if your DHCP pool is addresses 1-10, set up your first static address at 11. Then you will ensure you have no conflicts. Or reduce the size of the pool to 1-8 and set the first static address as 9 - either way you want to keep your DHCP pool and your static addresses separate to prevent conflicts.

OK now i see, my error was that I did not know that you could have static IP address outside the DHCP range I will re-assign.

 

[aaronwt]

Or just set the static addrees in the router also. I assign all my IP addresses in my router using the MAC address of each device. Each device only uses the specific IP address I assign to that specific MAC address. Although I use a number starting with 210. Why does everyone always seem to use the same IP addreses?(192.168.*.*)

 

[rhizopod]

Or just set the static addrees in the router also. I assign all my IP addresses in my router using the MAC address of each device. Each device only uses the specific IP address I assign to that specific MAC address. Although I use a number starting with 210. Why does everyone always seem to use the same IP addreses?(192.168.*.*)

It's just easiest because that's the default subnet for the gateway on most consumer routers. I use 192.168.*.* for my 802.11x network and 172.16.*.* for my Gigabit network.

Aside, this thread has gotten me thinking that I might need to upgrade my router. I don't think my linksys has any of the features mentioned in this thread, including the one above. Can someone recommend a reliable, well-featured wireless router that offers a good interface and high level of configurability at a decent price? I am willing to pay a bit more for a premium product.

(Oh, and turning off uPnP in my router solved my original problem. Thanks for the tips, and the skinny on uPnP, guys.)

 

[vman41]

It's just easiest because that's the default subnet for the gateway on most consumer routers. I use 192.168.*.* for my 802.11x network and 172.16.*.* for my Gigabit network.

Note that that is not an arbitrary default, RFC 1957 specifically reserves 3 address ranges for private networks:

• 10.0.0. - 10.255.255.255
• 172.16.0.0 - 172.31.255.255
• 192.168.0.0 - 192.168.255.255

Any number of private networks can re-use these addresses without global coordination and ISPs will not route them.

A quick search of my web server's logs definitely shows addresses with 210 as their first octet have been assigned to ISPs as global internet addresses.

 

[Saturn]

From the DHCP RFC:

The server should use whatever information is
available in the configuration information repository to choose an
address to reuse. For example, the server may choose the least
recently assigned address. As a consistency check, the allocating
server SHOULD probe the reused address before allocating the address,
e.g., with an ICMP echo request, and the client SHOULD probe the
newly received address, e.g., with ARP.

"SHOULD"

This word or the adjective "RECOMMENDED" means that there
may exist valid reasons in particular circumstances to ignore
this item, but the full implications should be understood and
the case carefully weighed before choosing a different course.

Essentially, the DHCP server SHOULD, but is not required to check that an address is in use (via ICMP echo, a.k.a. ping) before handing out an IP for it.

Even so (as Chipware stated above) unless the static computer is on all the time, the DHCP server may hand out that IP address when the static computer isn't responding and you won't have an IP conflict until it is booted up.