Networking n00bie needs a genius! Or a life jacket.

Forums › LAN (ethernet/Wifi/routers/Bluetooth) › Networking n00bie needs a genius! Or a life jacket.

DravidDavid

1907 posts

Uber Geek

#65114 29-Jul-2010 19:51

I have this situation at school. After hours everyone plays Call of Duty 4. There are 3 computer labs. Two up top, one down bottom.

Anyone in the top labs can host and they all see the server fine and dandy. But the bottom lab cant see the server the top is hosting. This goes both ways. Top can't see bottom either.

All three are on the same domain(slic.ac.nz) and subnet(255.255.0.0) The IP range the bottom lab is on is: 172.16.1.XX

The top lab is on: 172.20.0.XX

If the game is hosted in the top lab and I know the IP of the host. I can connect via IP (/connect 172.20.0.XX) But when you have approximatly 80 people wanting to play at different times each with their own server...Its hard to keep track of the hosts.

Each IP is dynamic with DHCP enabled, so a dedicated server is sotra' out of the question. Especially since all servers on static IPs are at 100% capacity almost 24/7.

Is there anything I can do to sniff out the computers on the other range with traffic in relation to Call of Duty 4 on port 28960? I have Wireshark installed and have been told this can do exactly what I want. But I tried for hours and could only sniff my own traffic, which is pretty much pointless. I've looked for programs such as LAN game searchers and stuff. XFire should work in theory, but it dosn't...So I'm stuck.

Anyone have a solution to my problem?

Cheers guys!

ArcticSilver

729 posts

Ultimate Geek

#358769 29-Jul-2010 20:19

Firstly, re-wireshark, don't bother.

To use wireshark you really need to understand networking at a reasonable depth.

The problem you have from what you have typed is that your 2 labs are on different subnet's. Because of this no broadcasts go out for a LAN game, so no one can find it in their list. They must have a router or layer 3 switch routing between the labs, this is why you can still connect on the other subnet.

There is really no easy fix.

DravidDavid

1907 posts

Uber Geek

#358779 29-Jul-2010 20:24

So I can't magicly just change all the details in my network configuration to mimic the top lab's and use an IP that they arn't using to get connected on their side of the network?

ArcticSilver

729 posts

Ultimate Geek

#358797 29-Jul-2010 20:39

DravidDavid: So I can't magicly just change all the details in my network configuration to mimic the top lab's and use an IP that they arn't using to get connected on their side of the network?

You cannot, since it will be routed between the two networks.

Basically put, routing runs at level 3 which kills layer 2 broadcasts (your application).

DravidDavid

1907 posts

Uber Geek

#358806 29-Jul-2010 20:44

Ugh...

Thanks for your help guys...I always seem to be on the short end of the stick when it comes to this stuff! I can't just be normal for once and be able to do everything everyone else does without having to jump through hoops trouble-shooting all the time can I?

I just had a thought...If I added EVERYONES IP to my favorites list...The active one would be picked up since it was entered manually.

If I got hold of a machine on the other subnet, could I find out everyone elses IP on that particular network? Or would I have to go to each machine and find out the IPs that way?

ArcticSilver

729 posts

Ultimate Geek

#358831 29-Jul-2010 20:58

DravidDavid: Ugh...

Thanks for your help guys...I always seem to be on the short end of the stick when it comes to this stuff! I can't just be normal for once and be able to do everything everyone else does without having to jump through hoops trouble-shooting all the time can I?

I just had a thought...If I added EVERYONES IP to my favorites list...The active one would be picked up since it was entered manually.

If I got hold of a machine on the other subnet, could I find out everyone elses IP on that particular network? Or would I have to go to each machine and find out the IPs that way?

You could guess, but there would be no definite answer.

It'd most likely be within 1 - 254 (the last digit) though =P

DravidDavid

1907 posts

Uber Geek

#358835 29-Jul-2010 21:02

Ok...Looks like thats out of the question then.

Is there some program that will sift through all subnets and find computers transmitting TCP/UDP traffic on certain ports so I can narrow it down to say the IPs of people playing and hit and miss with the host IP?

This is looking like my best option so far. If Wireshark is off the table, is there another that is easier to use or does what I described?

ArcticSilver

729 posts

Ultimate Geek

#358848 29-Jul-2010 21:07

DravidDavid: Ok...Looks like thats out of the question then.

Is there some program that will sift through all subnets and find computers transmitting TCP/UDP traffic on certain ports so I can narrow it down to say the IPs of people playing and hit and miss with the host IP?

This is looking like my best option so far. If Wireshark is off the table, is there another that is easier to use or does what I described?

I don't mean to be rude when i say this, but your best bet is really to stick with asking the host. There is ways but they are not easy and they would be extremely confusing if you do not know networking.

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DravidDavid

1907 posts

Uber Geek

#358862 29-Jul-2010 21:15

ArcticSilver:
DravidDavid: Ok...Looks like thats out of the question then.

Is there some program that will sift through all subnets and find computers transmitting TCP/UDP traffic on certain ports so I can narrow it down to say the IPs of people playing and hit and miss with the host IP?

This is looking like my best option so far. If Wireshark is off the table, is there another that is easier to use or does what I described?

I don't mean to be rude when i say this, but your best bet is really to stick with asking the host. There is ways but they are not easy and they would be extremely confusing if you do not know networking.

Understood. I'll keep trying Wireshark when I have the time. I'm sure I can figure it out.

Thanks for the information though. I'll talk to the IT guy and see what he says about the setup. Maybe he can forward a port or something.

webwat

2036 posts

Uber Geek

Trusted

#360253 30-Jul-2010 19:09

DravidDavid: So I can't magicly just change all the details in my network configuration to mimic the top lab's and use an IP that they arn't using to get connected on their side of the network?

They dont need to forward a port because it appears to be routed or switched normally on your LAN. A router will prevent MAC addresses coming through to your subnet, but if you are on the same LAN as the other lab (ie the router doesnt separate the layer2 traffic) there is a way. Type this in DOS: arp -a (it will display the IP for all MAC addresses visible to your local switch). Sorry its not magic, you just have to ask the right piece of equipment. Unfortunately it will not tell you what each machine is doing.

You could ask your friend to send you a message to find either the computer's IP or its name (so that you can ping the name to get its IP). In DOS type: net send 172.20.x.x message... where "x" is your IP, but you wont receive that unless "windows messenger" is running as a service under "Services" in the control panel. You might have to ask the IT guy about that if you want to try it.

Time to find a new industry!

ArcticSilver

729 posts

Ultimate Geek

#360413 30-Jul-2010 21:33

webwat:
DravidDavid: So I can't magicly just change all the details in my network configuration to mimic the top lab's and use an IP that they arn't using to get connected on their side of the network?

They dont need to forward a port because it appears to be routed or switched normally on your LAN. A router will prevent MAC addresses coming through to your subnet, but if you are on the same LAN as the other lab (ie the router doesnt separate the layer2 traffic) there is a way. Type this in DOS: arp -a (it will display the IP for all MAC addresses visible to your local switch). Sorry its not magic, you just have to ask the right piece of equipment. Unfortunately it will not tell you what each machine is doing.

You could ask your friend to send you a message to find either the computer's IP or its name (so that you can ping the name to get its IP). In DOS type: net send 172.20.x.x message... where "x" is your IP, but you wont receive that unless "windows messenger" is running as a service under "Services" in the control panel. You might have to ask the IT guy about that if you want to try it.

The problem is he is on 2 different address ranges, 2 different subnets. Because if this traffic must be routed between for communication which in turn kills all broadcasts. In another words without doing a directed broadcast (which should be blocked anyway) the game will not be able to pick up a game server broadcast on the other network.

Simply put, its like 2 people trying to communicate between 2 different locations, sure they can yell out the server information but no one at the second location will hear them. The only way to communicate is to pick up the phone.