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sniffing Rich's box

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As network administrator, it's my job to make sure that the Housemate's toys all work nice with the internet and stuff, as well as keeping the poor dears safe from outside interference. (go on, just try my firewall. it'll kick your ass.)

However. The new xbox 360 is being an utter b.a.s.t.a.r.d. So much so, I've had to resorting to sniffing packets to try and figure out how to make it happy.

still, learning lots more about the inner workings of networking. not that I wanted to know.

23rd Mar 2006, 17:46   | tags:,,,,

Steve says:

Great title, thanks that has cheered my up

23rd Mar 2006, 18:00

Joe says:

mm ethereal

23rd Mar 2006, 18:19

beth says:

sniffing packets? is this some kind of geek drug i've never heard of..

23rd Mar 2006, 18:19

Joe says:

yes, but you're not geeky enough to enjoy it....yet

23rd Mar 2006, 18:20

mat says:

tethereal. it's one more hardcore than the gui version. :)

23rd Mar 2006, 18:22

beth says:

: /

23rd Mar 2006, 18:27

Electric Sheep says:

-T psml and upload the file!?

23rd Mar 2006, 18:47

mat says:

This is what you get when you run the 'test connection' stuff on the xbox. it keeps failing on the MTU test, which is what's throwing me. I know about the PNAT issue, I'm ready for that (either with port forwarding by hand or via upnp), but this really shouldn't be happening...

any advice appreciated. :)

23rd Mar 2006, 19:09

mat says:

I wonder if there's a router somewhere between there and here that's throttling the MTU.. ICMP type three packets are allowed in and out of the firewall, so that shouldn't be a problem. I did try clamping MSS to 1440, but that didn't make any difference. I'm sending MTU values out by dhcp, and explicitly setting it on eth0 (which makes no difference)


I'm starting to think there's something wrong with teh xbox. But we can't get online under Windows becuase of some unknown problem with the XP laptop.

23rd Mar 2006, 19:14

JokerXL says:

I'm gonna start speaking Dutch on here one day, so you'se will all know how I feel, reading this lot!

23rd Mar 2006, 20:50

Rich says:

Joker: I have to live here!

Not that I'm complaining, our network is nails 'ard. Plus everyone at work thinks I'm a computer expert, simply because I know how to use the tab key.

23rd Mar 2006, 21:12

Helen says:

But you just press it, don't you? And that's it...

Helen's solution: Throw the XBox out the window.

23rd Mar 2006, 22:41

beth says:

rich : but you told me you were going to take over the world?

23rd Mar 2006, 22:45

daz says:

Mat: The Boy says you should look here:

23rd Mar 2006, 22:55

mat says:

Thanks Boy-via-Daz, but I have the upnp daemon installed and running already (and I know the workaround for if it doesn't work) - but the xbox is failing before it tests for upnp. it's failing on MTU, which is daft.

bloody stupid thing.

23rd Mar 2006, 23:03

beth says:

i think it's dead mat.

23rd Mar 2006, 23:04

Joe says:

ah the wonders of microsoft

23rd Mar 2006, 23:06

Rich says:

It's the quintessence of microsoft.

23rd Mar 2006, 23:14

daz says:

Mat: Is the server If yes, then something's wrong with the forwarding - the server tries to connect to itself from source port 1259 to destination 3074, according to the tcpdump.

23rd Mar 2006, 23:20

mat says: is the xbox. is the gateway.

xbox is getting dhcp OK, getting DNS fine, just claiming that the MTU is too low. it's not too low inside my damn network, I'm sure. I need to do some more diagnostics...

that is a good point though, it does look like it's trying a loopback connection. weirder and weirder.

23rd Mar 2006, 23:23

daz says:

What happens if you set the MTU higher, then? And how does the xbox tell you the MTU is too low? It doesn't say that in the tcpdump.

(Just typing what I'm being told here. :))

23rd Mar 2006, 23:25

mat says:

I can only set the MTU on the eth0 interface to 1500, because that's ethernet. The MTU on the ppp connection is 16K, so that should be OK.

I don't know why the xbox thinks the MTU is too low - we get a hex errorcode, but it's pretty useless on it's own. I think that it's sending out packets to do path MTU discovery, and some router along the way from here to xbox live is throttling the packets.. There does seem to be a distinct lack of TCP action towards the bottom of that dump though.. gah.

I'm getting a bit out of my depth with this now, although I do keep learning stuff.. Firewalls, I can do. Port forwarding, easy. Low-level network diagnostics? Little shaky there... :)

23rd Mar 2006, 23:33

daz says:

(The Boy just got up and sat down in front of his computer, I think he's trying to find you some info..)

23rd Mar 2006, 23:37

Steve says:

Isn't there a connection wizard? Maybe the giant microsoft paperclip can help? "It looks like you are typing a letter!"

24th Mar 2006, 12:07

Rich says:

HURRR. Thanks steve, would never have thought of that without you.

24th Mar 2006, 12:09

Steve says:

We aim to please

24th Mar 2006, 16:51