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uPNP - what is it?

VileReynard
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uPNP - what is it?

Does windows require uPNP and what is it?
My windows PC's keep having intermittent wireless problems, whilst Linux "just works".

26 REPLIES
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Re: uPNP - what is it?

This will tell you what it is: Universal Plug and Pray
jelv (a.k.a Spoon Whittler)
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severedsolo
Grafter
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Registered: ‎09-03-2010

Re: uPNP - what is it?

its a damn security risk is what it is....
uPnP is short for Universal Plug and Play, what this is SUPPOSED to do, is open up ports for applications that need them (things like Voice over IP and p2p software mainly) but it can be exploited by people tryng to hijack your computer.
Any decent router, with a built in NAT firewall, SHOULD reject unsolicited incoming connections (ie ones that you havent sent out a request to open from your PC) unfortunately some software needs an incoming connection without sending a request first (for instance, VOIP needs an incoming connection because you dont know that someone is going to call you) this is what Port Forwarding is for, it basically says "dont block connections on this port, just send them straight to this PC"  this is known as "pinholing" your firewall, because you make a hole in the firewall to allow data through. uPNP is supposed to automate this process,
unfortunately, some less than scrupulous people exploit this by making their software open a hole in your firewall so they can do nasty things to your computer. If you know how to port forward, then i would suggest disabling uPNP and opening ports for any apps that need them, (and it will be less than 5 i can almost guarantee it) if you dont, then take a look at http://portforward.com for everything you need to know, as well as guides to set up port forwarding for most applications that need it and most major routers
VileReynard
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Re: uPNP - what is it?

I disabled uPNP and a Windows XP PC & a Windows 7 PC both failed to achieve a wireless connection - DHCP was showing an aquired ip address of 0.0.0.0
It seems that M$ are trying to crowbar a Windows protocol into the the TCP stack?
My uPNP ports opened by a Windoze 7 PC:-
Quote
Active  	Protocol  	Int. Port  	Ext. Port  	IP Address
YES         UDP     60027     60027       192.168.1.6
YES         UDP     30020     30020       192.168.1.6
YES         TCP     30020     30020       192.168.1.6

Seems like these are easy numbers to guess - and why are the internal & external ports the same on the last entry?

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Re: uPNP - what is it?

I find it hard to believe that such a keen advocate of Linux needs to wrestle with Windows.  Why use Windows at all if "Linux just works"?  On Windows XP I found very little that needed uPNP but the installation/run routines for software that calls for uPNP are never smart enough to alert you if uPNP is turned off, so it's a bit dangerous to disable it.  I know it was touted as a terrible security risk but that never really came to pass, did it?  I used to turn it off on XP but gave up because when this caused problems with legitimate software it was very difficult to trace the cause and I couldn't find any evidence in the field that it was being exploited by illegitimate software.
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Re: uPNP - what is it?

Quote from: A
I disabled uPNP and a Windows XP PC & a Windows 7 PC both failed to achieve a wireless connection

Where did you disable it?
I sometimes use uPNP and sometimes not but it has NEVER stopped me getting a  normal connection, wired or wireless.  Undecided
Maybe (probably) you've got something else wrong.
VileReynard
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Re: uPNP - what is it?

I disabled uPNP in the router.
I've since re-enabled it.
As a result the Windows 7 PC didn't initially work, but after a wait of about 30 minutes, it did. Crazy
The Windows XP PC firmly refuses to work though.
Given the opportunity, I would dump Windows like a shot (but I am not allowed to!).  Cheesy

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Re: uPNP - what is it?

Quote from: A
I disabled uPNP in the router.
I've since re-enabled it.

Well I turn it (uPNP) on and off (in the router) all the time to suit my needs.
All my systems continue to work fine, though obviously uPNP-related stuff is affected.
I have XP, Vista and W7 (wired and wireless) and just use standard DHCP-supplied TCP/IP parameters (except one PC where I've set DNS manually).
As I said before:
Quote
Maybe (probably) you've got something else wrong.

The 30-minute wait suggests a lease timeout so I'd look at the LAN settings in the router first.
I think uPNP is largely a red herring and not at fault, it may "just" be enabling W7 to get round a misconfiguration of your network when it is enabled.
VileReynard
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Re: uPNP - what is it?

I think you are right HP.
It looks DHCP is screwed up - this morning DHCP "works" - with a lease time of 24 hours.
However - whilst I can see (and access) the router, I cannot Windows to access the internet with ping (or anything else).
I will try to post the ipconfig output sometime...

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Re: uPNP - what is it?

I agree with HPsauce
Quote
I think uPNP is largely a red herring and not at fault, it may "just" be enabling W7 to get round a misconfiguration of your network when it is enabled.

As an experiment, on your Windows XP machine, does it work if you don't use DHCP ? - i.e. set the windows network configuration to an unused static IP address, and point the DNS at  reliable servers such as 8.8.4.4 and 208.67.220.220.
This experiment will bypass DHCP and any odd effects your uPnP might be having, and point to a problem with you router/gateway.
If this does work, you might want to either set your whole network to static IP addresses, OR setup a Linux PC with "dnsmasq" which provides a caching DNS server AND DHCP.
severedsolo
Grafter
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Registered: ‎09-03-2010

Re: uPNP - what is it?

What i dont understand is how uPNP is fixing the problem, DCHP and uPNP are related to two completely seperate functions...
I agree its a DCHP problem though, personally i would try turning DCHP off (for now) and seeing if it works on Static IP's. just a thought.... you dont think that DCHP is giving you a different IP every time and so your previous forwarding (set up by uPNP) is failing as its trying to forward to the wrong IP do you? do you have "reserved addresses" in the DCHP pool? or do you just let it do its thing?
for instance, on my router (a Dlink DSL-2640R) although DCHP is on, and gives IP's to all machines, my main computer has 192.168.1.2 "reserved" from the DCHP pool, so that ONLY this machine will get that IP address, and it will ALWAYS get given it by DCHP because of my port forwarding, all the other machines just get given whatever's available
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Re: uPNP - what is it?

Quote from: severedsolo
What i dont understand is how uPNP is fixing the problem,

I think it's only the W7 system where it does.
As W7 also supports uPNP then this quote from Wikipedia may explain:
"The UPnP architecture supports zero-configuration networking. A UPnP compatible device from any vendor can dynamically join a network, obtain an IP address, announce its name, convey its capabilities upon request, and learn about the presence and capabilities of other devices. DHCP and DNS servers are optional and are only used if they are available on the network. Devices can leave the network automatically without leaving any unwanted state information behind."
All points to a DHCP problem.  Wink
VileReynard
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Re: uPNP - what is it?

Thanks to @HP, @severed and @purleigh:-
BTW (@purleigh, I too used to have a Dlink 2640, and the ip address is likewise reserved from the DHCP pool)
I now have a Netgear DG834Gv5...
OK:- Cheesy
I tried the static address approach - but although I could ping the PC's static address, it failed to find the gateway (router) address Cry
So I set it back to DHCP and disabled the firewall Cheesy
This afternoon I did a ipconfig /renew (to force getting a new DHCP lease).
Results of ipconfig /all
Quote
Windows IP Configuration
        Host Name . . . . . . . . . . . . : DALEK
        Primary Dns Suffix  . . . . . . . :
        Node Type . . . . . . . . . . . . : Hybrid
        IP Routing Enabled. . . . . . . . : No
        WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Wireless Connection 2:
        Connection-specific DNS Suffix  . :
        Description . . . . . . . . . . . : Atheros AR5006EG Wireless Network Adapter
        Physical Address. . . . . . . . . : 00-16-E3-65-9B-55
        Dhcp Enabled. . . . . . . . . . . : Yes
        Autoconfiguration Enabled . . . . : Yes
        IP Address. . . . . . . . . . . . : 192.168.1.64
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 192.168.1.1
        DHCP Server . . . . . . . . . . . : 192.168.1.1
        DNS Servers . . . . . . . . . . . : 192.168.1.1
        Lease Obtained. . . . . . . . . . : 05 June 2010 15:16:10
        Lease Expires . . . . . . . . . . : 06 June 2010 15:16:10

I can now see the router and signin to the router interface, so port 80 must be open.
However, I cannot access the internet and (interestingly) ping www.plusnet.co.uk gives:-
Quote
Pinging portal.plus.net [212.159.8.2] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Ping statistics for 212.159.8.2:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

Which looks like DNS works (at least on the LAN side)?
ping 212.159.8.2 fails although it works on other PC's Smiley
I also tried a "arp -a" command and it only had one entry - I assume that's correct?
All help gratefully accepted... Cry Cry

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Re: uPNP - what is it?

Why 192.168.1.1, most Netgears will normally use 192.168.0.1 as the gateway?
VileReynard
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Re: uPNP - what is it?

I changed it. Cheesy
(Actually it was because I had a Thomson(?) router for a bit and I like to force preset ip addresses.
This allows me to use a hosts file to address PC's by name.
It's O.K. for a couple of PC's - but it's got a bit out of hand now...