Once and for all: let's clear this GIT setup hassle

Gamer's Internet Tunnel, formerly Gamer's IPX Tunnel

Once and for all: let's clear this GIT setup hassle

Postby huwkka » Mon Mar 07, 2005 8:38 am

So, many people have been wondering why does not GIT work and so on. I am one of them. Everything should work, but even ping is timed out.

My setup: 2 computers

computer1
connected to internet with ip a.b.c.d

computer2
connected to internet with ip e.f.g.h

the ip addresses are random, and assigned by dhcp of the ISP

I have set the ip's in the wizard, the connection status says the GIT connection is up and running, tells last routed packet and so on. But how the heck am i supposed to use this connection ? Please help.

edit: version used: git 0.99beta4
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Postby huwkka » Mon Mar 07, 2005 11:42 am

a many hour lasting testing has come to a point where we set up microsoft virtual loopback adapter on each computer, set GIT to capture frames of the virtual adapter.

So the virtual adapter is set to 192.168.0.1 and 192.168.0.2 on the two computers.

So when i try to ping .1 from .2 computer, the forwarded log says this:

[Mon Mar 07 20:05:42 2005] network: hw:02:00:4c:4f:4f:50 EthernetII ARP request to:00:00:00:00:00:00 from:02:00:4c:4f:4f:50(192.168.0.2) for:192.168.0.1 'ok'

and the incoming log on .1 says:

[Mon Mar 07 20:06:05 2005] 0.0.0.0: hw:02:00:4c:4f:4f:50 EthernetII ARP request to:00:00:00:00:00:00 from:02:00:4c:4f:4f:50(192.168.0.2) for:192.168.0.1 'ok'

what is still wrong when the logs seem to teel averything is fine, and still the ping gets a timeout ?!
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Postby Ark » Mon Mar 07, 2005 11:57 am

ARP is not PING. Check your firewalls. Check that you are actually forwarding ICMP on both sides of GIT.
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Postby huwkka » Mon Mar 07, 2005 12:39 pm

that is the only thing that comes to the logs when typing ping ip in windows command prompt and the same thing comes when trying to connect with a game.

Windows firewall turned off, no other firewalls active, no nat, both GIT in advanced configuration checked tcp, udp and icmp...

edit:
when searching for a computer in windows search from the taskbar this comes some twenty times in the log:

[Mon Mar 07 21:07:21 2005] 0.0.0.0: hw:02:00:4c:4f:4f:50 EthernetII IPv4 UDP to:192.168.0.255:137 from:192.168.0.2:137 'ok'
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Postby Ark » Mon Mar 07, 2005 12:52 pm

If you are forwarding ICMP (all ping is icmp, but not all icmp is ping) then you will see lines like this:

[Mon Mar 07 14:16:03 2005] network: hw:xx:xx:xx:xx:xx:xx EthernetII IPv4 ICMP to:10.1.2.3:12124 from:10.1.1.2:2048 'ok'

The log lists port numbers for all IPv4 frames, even though its just garbage for ICMP, so ignore the 12124 / 2048 numbers.

If you are not forwarding ICMP, it will probably show up in the unforwarded log.
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Postby huwkka » Mon Mar 07, 2005 12:58 pm

well, i also seem to have this in the logfile now after some mixed attempts to connect to the computer:

incoming.txt

[Mon Mar 07 21:12:42 2005] 0.0.0.0: hw:02:00:4c:4f:4f:50 EthernetII IPv4 ICMP to:192.168.0.255:58879 from:192.168.0.2:2048 'ok'
[Mon Mar 07 21:12:46 2005] 0.0.0.0: hw:02:00:4c:4f:4f:50 EthernetII IPv4 ICMP to:192.168.0.255:58623 from:192.168.0.2:2048 'ok'
[Mon Mar 07 21:12:50 2005] 0.0.0.0: hw:02:00:4c:4f:4f:50 EthernetII IPv4 ICMP to:192.168.0.255:58367 from:192.168.0.2:2048 'ok'

so icmp is forvarded ? but not working the way it's supposed to. and why is the last ip in the block .255 always. Is this normal or ?

edit: my computers are assigned the ip's 192.168.0.1 and 192.168.0.2
Last edited by huwkka on Mon Mar 07, 2005 1:16 pm, edited 1 time in total.
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Postby Ark » Mon Mar 07, 2005 1:14 pm

That .255 means something is broadcasting. It should be quite clear that 192.168.0.2 is sending a broadcast packet to 192.168.0.255/24
This could be any number of things other then ping, such as a border gateway protocol trying to locate what computers are on the network in order to properly route traffic to the internet.
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Postby huwkka » Mon Mar 07, 2005 1:24 pm

So you have nothing left that you could think would solve this problem. GIT is up and working, something sends both arp icmp and udp packets thru the tunnel but i personally cannot use the tunnel to anything.
This feels kinda frustrating... maybe this has something to do with the virtual loopback adapters ? well, i really don't know.
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Postby Ark » Mon Mar 07, 2005 1:31 pm

GIT is only as good as the options you set and the network you have configured. I can only help with specific questions as to how GIT operates, not anything specific to your particular network setup.
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NAT

Postby azuur » Mon Mar 07, 2005 8:23 pm

How does the internal / External work? What does that do?

I have been messing with GIT over pptp, which works great for most parts, but the client is sending the packets with its public IP.

I'm going to give it a try through the firewall and see how that works, any tips for 2 clients on a "LAN" game, one behind NAT, the other with a public IP.
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Re: NAT

Postby Ark » Mon Mar 07, 2005 9:04 pm

azuur wrote:How does the internal / External work? What does that do?


What are you referring to specifically here?

azuur wrote:I have been messing with GIT over pptp, which works great for most parts, but the client is sending the packets with its public IP.


Are you referring to the packets GIT tunnels, or the tunneled packets GIT sends to the other GIT?
The packets GIT sends to the other GIT are sent using normal winsock interfaces and are sent as windows sees fit. The packets GIT captures and tunnels inside of these packets are captured exactly as the application that send them made them. GIT does not modify these packets except for the 'alter source IP for nat' option, which is almost always a BAD idea to use, unless you KNOW for a fact that its what you want.


azuur wrote:I'm going to give it a try through the firewall and see how that works, any tips for 2 clients on a "LAN" game, one behind NAT, the other with a public IP.


This depends on the game. Some games can not at all, in any way, work with that kind of network setup, unless maybe you install a virtual network adapter on the non-NAT one and use the same subnet and IP range as the other computer with NAT, but use a different IP.
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Postby azuur » Fri Mar 11, 2005 5:08 pm

How does the internal / External work? What does that do?
What are you referring to specifically here?


Sorry, the Internal / External fields of the NAT section.

It appears the games I am trying to make work apparently will only bind to the LAN NIC IP address of the computer. I have tried playing with the bindings of the adapters in Windows, but regardless of that the game binds to the LAN NIC, rather then the PPTP adapters IP. Even when the remote client establishes a PPTP session to my network and is on the same subnet as me, the packets still arive with the NIC IP instead of the PPP IP, this is the game binding I think and theres nothing I can do about it, other then try to work around it.

GIT does not modify these packets except for the 'alter source IP for nat' option, which is almost always a BAD idea to use, unless you KNOW for a fact that its what you want.


That may be what I need. This is the feature I would like to know more about. This sounds like it will replace the IP header with the IP you specify in this field? How do both halfs to this, internal and external come into play with GIT rebuilding the packet?

thx for the reply
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Postby Ark » Sat Mar 12, 2005 1:40 am

Some GIT options affect the sending side only. Alter Source IP is one of those options. On the sending side, packets are sniffed from the network, checked against the various rules, then tunneled to the other GIT. Alter Source IP will simply change the IPv4 source IP of all packets that match the 'from' field to the 'to' field, right before the packet is sent into the tunnel. The other side does not use the alter source IP for receiving the tunneled packet and re-broadcasting it to the network on the other side.
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Postby azuur » Tue Mar 15, 2005 7:35 pm

The good news is I got it to work with one game! You'd think EA would use the same network transport for all thier games, but noooo that would be too easy!!

Alter Source IP will simply change the IPv4 source IP of all packets that match the 'from' field to the 'to' field, right before the packet is sent into the tunnel.


So this just changes the Source IP of the GIT packet itself? (ie. UDP 213)?
Since this is done before being put on the wire, you can specify any IP in the To field. I put my NIC true IP in the From box, and 10.10.10.10 in the From box. Started GIT. The packets arrived at the other end with the IP of the NIC on it still. Am I missing something? (I checked the box too :P)
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Postby Ark » Tue Mar 15, 2005 7:42 pm

No, it does not change the source IP (the one sending from port 213). The source IP is your primary NIC's IP, with a source port of 213 and a destination port of 213. The destination IP is specified in your connections, and is the other computer running GIT. If you are NAT'd, the source IP of the GIT connection is already altered by your NAT gateway. That is what NAT does.

What GIT modifies is the packet that is going inside of the tunnel (the packet which is sniffed from your network).

The packets that GIT sends to the other GIT are basically formatted as such:

[Ethernet header [IPv4 header** [UDP header++ [GIT header [Ethernet header [IPv4* header [UDP header+ [Game Data]]]]]]]]

* is what GIT modifies the source of.
** is what NAT modifies the source of, simply by virtue of what NAT does (network ADDRESS translation)

+ is where the game ports source/destination are
++ is where the GIT ports (213) are
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