Networking issues - firewalls and spring

[MrPresident]

Hi all

Im trying to find out / make some kind of Layer7 module for spring, so it will work through any linux iptables firewall using Layer7 application packet inspection (so it would be, moreless, the same as UPnP).

First, i would ask if anybody knows of any kind of work about this.

Second, if nobody knows anything, i would like to start working on this (or, at least, try to start working on this), so ill need info about the syntax / format of the network packets Spring uses. Where can i find info about this?

If you have more interests on Layer7, check out:

l7-filter.sourceforge.net

l7-filter.sourceforge.net/protocols

Thx all

[Auswaschbar]

Hi,

a basic overview can be found in springs sourcecode, heres comes the relevant part:

How Spring protocolheader looks like (size in bytes):
4 (int): number of packet (continuous)
4 (int): last in order (tell the client we recieved all packages with packetNumber less or equal)
1 (unsigned char): nak (we missed x packets, starting with firstUnacked)

If you need more info about the different packet types, please read this: http://www.osrts.info/~buildbot/spring/ ... ource.html

I hope this helps you

[Tobi]

As far as I know no one is working on this.

The format of the network packets can be found in the files in rts/System/Net/, I can not look it up currently though.

Out of my head it is a 9 byte header of 4 byte packet number, 4 byte ack (last in order received packet) and 1 byte nack (which/how much packets to resend). Then follows raw data defined by NETMSG_* constants.

Basically this means that Spring packets are quite different each time since there is nothing like a magic number in them.

edit: ugh, I shouldn't keep the post reply page open so long...

[MrPresident]

Buff...

That sounds bad. Well, ill try to check it anyway.

Thx a lot