Oh this may help too, salomo is running the client, and worrelsik is  
running the server

tcpdump: verbose output suppressed, use -v or -vv for full protocol  
decode
listening on eth1, link-type EN10MB (Ethernet), capture size 96 bytes
22:48:33.755591 IP salomo.luky.nl.49467 > worrelsik.luky.nl.netrek: S  
3218268111:3218268111(0) win 65535 <mss 1460,nop,wscale  
0,nop,nop,timestamp 460745823 0>
         0x0000:  4500 003c bb89 4000 4006 fbd6 c0a8 0105   
E..<.. at .@.......
         0x0010:  c0a8 0106 c13b 0a20 bfd2 dfcf 0000  
0000  .....;..........
         0x0020:  a002 ffff d4d8 0000 0204 05b4 0103  
0300  ................
         0x0030:  0101 080a 1b76 6c5f 0000 0000            .....vl_....
22:48:33.756549 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: S  
305951056:305951056(0) ack 3218268112 win 5792 <mss  
1460,nop,nop,timestamp 1164940136 460745823,nop,wscale 2>
         0x0000:  4500 003c 0000 4000 4006 b760 c0a8 0106   
E..<.. at .@..`....
         0x0010:  c0a8 0105 0a20 c13b 123c 7150 bfd2  
dfd0  .......;.<qP....
         0x0020:  a012 16a0 61c1 0000 0204 05b4 0101  
080a  ....a...........
         0x0030:  456f 9368 1b76 6c5f 0103 0302            Eo.h.vl_....
22:48:33.755775 IP salomo.luky.nl.49467 > worrelsik.luky.nl.netrek: .  
ack 1 win 65535 <nop,nop,timestamp 460745823 1164940136>
         0x0000:  4500 0034 bb8a 4000 4006 fbdd c0a8 0105  E.. 
4.. at .@.......
         0x0010:  c0a8 0106 c13b 0a20 bfd2 dfd0 123c  
7151  .....;.......<qQ
         0x0020:  8010 ffff a427 0000 0101 080a 1b76  
6c5f  .....'.......vl_
         0x0030:  456f 9368                                Eo.h
active++: 1: pid 31844 port 2592
22:48:34.003112 IP salomo.luky.nl.49467 > worrelsik.luky.nl.netrek: P  
1:9(8) ack 1 win 65535 <nop,nop,timestamp 460745823 1164940136>
         0x0000:  4500 003c bb8d 4000 4006 fbd2 c0a8 0105   
E..<.. at .@.......
         0x0010:  c0a8 0106 c13b 0a20 bfd2 dfd0 123c  
7151  .....;.......<qQ
         0x0020:  8018 ffff 0d52 0000 0101 080a 1b76  
6c5f  .....R.......vl_
         0x0030:  456f 9368 1b04 0a00 3728 3a99            Eo.h....7(:.
22:48:34.003163 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: .  
ack 9 win 1448 <nop,nop,timestamp 1164940198 460745823>
         0x0000:  4500 0034 e239 4000 4006 d52e c0a8 0106  E.. 
4.9 at .@.......
         0x0010:  c0a8 0105 0a20 c13b 123c 7151 bfd2  
dfd8  .......;.<qQ....
         0x0020:  8010 05a8 9e39 0000 0101 080a 456f 93a6  ..... 
9......Eo..
         0x0030:  1b76 6c5f                                .vl_
22:48:34.003810 IP salomo.luky.nl.49467 > worrelsik.luky.nl.netrek: P  
9:97(88) ack 1 win 65535 <nop,nop,timestamp 460745823 1164940198>
         0x0000:  4500 008c bb8e 4000 4006 fb81 c0a8 0105   
E..... at .@.......
         0x0010:  c0a8 0106 c13b 0a20 bfd2 dfd8 123c  
7151  .....;.......<qQ
         0x0020:  8018 ffff 1901 0000 0101 080a 1b76  
6c5f  .............vl_
         0x0030:  456f 93a6 3c53 0000 0000 0001 4645 4154   
Eo..<S......FEAT
         0x0040:  5552 455f 5041 434b 4554 5300 0000 0000   
URE_PACKETS.....
         0x0050:  0000                                     ..
22:48:34.003858 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: .  
ack 97 win 1448 <nop,nop,timestamp 1164940198 460745823>
         0x0000:  4500 0034 e23b 4000 4006 d52c c0a8 0106  E.. 
4.;@. at ..,....
         0x0010:  c0a8 0105 0a20 c13b 123c 7151 bfd2  
e030  .......;.<qQ...0
         0x0020:  8010 05a8 9de1 0000 0101 080a 456f  
93a6  ............Eo..
         0x0030:  1b76 6c5f                                .vl_
22:48:34.004194 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: .  
1:1449(1448) ack 97 win 1448 <nop,nop,timestamp 1164940199 460745823>
         0x0000:  4500 05dc e23d 4000 4006 cf82 c0a8 0106   
E....=@. at .......
         0x0010:  c0a8 0105 0a20 c13b 123c 7151 bfd2  
e030  .......;.<qQ...0
         0x0020:  8010 05a8 4345 0000 0101 080a 456f  
93a7  ....CE......Eo..
         0x0030:  1b76 6c5f 0b00 0000 5765 6c63 6f6d  
6520  .vl_....Welcome.
         0x0040:  746f 2056 616e 696c 6c61 2073 6572 7665   
to.Vanilla.serve
         0x0050:  7220                                     r.
22:48:34.004213 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: .  
1449:2897(1448) ack 97 win 1448 <nop,nop,timestamp 1164940199 460745823>
         0x0000:  4500 05dc e23f 4000 4006 cf80 c0a8 0106  E....? 
@. at .......
         0x0010:  c0a8 0105 0a20 c13b 123c 76f9 bfd2  
e030  .......;.<v....0
         0x0020:  8010 05a8 a278 0000 0101 080a 456f  
93a7  .....x......Eo..
         0x0030:  1b76 6c5f 6f67 2020 2020 2020 2020  
2020  .vl_og..........
         0x0040:  2020 3a20 5965 7300 626c 6564 0000  
006f  ..:.Yes.bled...o
         0x0050:  0000                                     ..
22:48:34.004817 IP salomo.luky.nl.49467 > worrelsik.luky.nl.netrek: .  
ack 2897 win 65160 <nop,nop,timestamp 460745823 1164940199>
         0x0000:  4500 0034 bb8f 4000 4006 fbd8 c0a8 0105  E.. 
4.. at .@.......
         0x0010:  c0a8 0106 c13b 0a20 bfd2 e030 123c 7ca1  .....;..... 
0.<|.
         0x0020:  8010 fe88 99af 0000 0101 080a 1b76  
6c5f  .............vl_
         0x0030:  456f 93a7                                Eo..
22:48:34.004853 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: .  
2897:4345(1448) ack 97 win 1448 <nop,nop,timestamp 1164940199 460745823>
         0x0000:  4500 05dc e241 4000 4006 cf7e c0a8 0106   
E....A at .@..~....
         0x0010:  c0a8 0105 0a20 c13b 123c 7ca1 bfd2  
e030  .......;.<|....0
         0x0020:  8010 05a8 de3e 0000 0101 080a 456f  
93a7  .....>......Eo..
         0x0030:  1b76 6c5f 0000 0000 180d 0000 0000  
0000  .vl_............
         0x0040:  0000 0000 0000 0000 0000 0000 0000  
0000  ................
         0x0050:  0000                                     ..
22:48:34.004865 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: P  
4345:5769(1424) ack 97 win 1448 <nop,nop,timestamp 1164940199 460745823>
         0x0000:  4500 05c4 e243 4000 4006 cf94 c0a8 0106   
E....C at .@.......
         0x0010:  c0a8 0105 0a20 c13b 123c 8249 bfd2  
e030  .......;.<.I...0
         0x0020:  8018 05a8 b0e1 0000 0101 080a 456f  
93a7  ............Eo..
         0x0030:  1b76 6c5f 0000 0000 141c 0000 121c  
0000  .vl_............
         0x0040:  0000 0000 041c 0000 0000 0000 0000  
0000  ................
         0x0050:  181d                                     ..
22:48:34.071085 IP salomo.luky.nl.49467 > worrelsik.luky.nl.netrek: F  
97:97(0) ack 5769 win 65535 <nop,nop,timestamp 460745823 1164940199>
         0x0000:  4500 0034 bb93 4000 4006 fbd4 c0a8 0105  E.. 
4.. at .@.......
         0x0010:  c0a8 0106 c13b 0a20 bfd2 e030 123c 87d9  .....;..... 
0.<..
         0x0020:  8011 ffff 8cff 0000 0101 080a 1b76  
6c5f  .............vl_
         0x0030:  456f 93a7                                Eo..
22:48:34.071476 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: F  
5769:5769(0) ack 98 win 1448 <nop,nop,timestamp 1164940215 460745823>
         0x0000:  4500 0034 e245 4000 4006 d522 c0a8 0106  E.. 
4.E at .@.."....
         0x0010:  c0a8 0105 0a20 c13b 123c 87d9 bfd2  
e031  .......;.<.....1
         0x0020:  8011 05a8 8746 0000 0101 080a 456f  
93b7  .....F......Eo..
         0x0030:  1b76 6c5f                                .vl_
active--: 0: pid 31844 terminated
22:48:34.276188 IP worrelsik.luky.nl.netrek > salomo.luky.nl.49467: F  
5769:5769(0) ack 98 win 1448 <nop,nop,timestamp 1164940267 460745823>
         0x0000:  4500 0034 e247 4000 4006 d520 c0a8 0106  E.. 
4.G at .@.......
         0x0010:  c0a8 0105 0a20 c13b 123c 87d9 bfd2  
e031  .......;.<.....1
         0x0020:  8011 05a8 8712 0000 0101 080a 456f  
93eb  ............Eo..
         0x0030:  1b76 6c5f                                .vl_
22:48:34.276517 IP salomo.luky.nl.49467 > worrelsik.luky.nl.netrek: .  
ack 5770 win 65535 <nop,nop,timestamp 460745824 1164940267>
         0x0000:  4500 0034 bb95 4000 4006 fbd2 c0a8 0105  E.. 
4.. at .@.......
         0x0010:  c0a8 0106 c13b 0a20 bfd2 e031 123c 87da  .....;..... 
1.<..
         0x0020:  8010 ffff 8cb9 0000 0101 080a 1b76  
6c60  .............vl`
         0x0030:  456f 93eb                                Eo..
        salomo.luky.nl                   Sat May 20 22:48:33 2006

On 20 May 2006, at 22:44, Chris en Judith wrote:

> Hi
>
> i'm developing a new client based on Objective-C/Cocoa but have  
> difficulties figuring out the protocol required to establish a  
> connection to the server. So far i can connect to the server and  
> exchange some data but after the MOTD i get lost. Here's a  
> transcript of what i am trying:
>
> 2006-05-20 22:33:24.370 MacTrek[4128] SetupWindowController  
> awakeFromNib
> 2006-05-20 22:33:24.748 MacTrek[4128] SetupWindowController  
> raiseSetupWindow
> (gdb) continue
> 2006-05-20 22:33:32.469 MacTrek[4128]  
> ClientController.startClientAt: netrek.luky.nl port 2592
> 2006-05-20 22:33:32.473 MacTrek[4128] Communication.callServer:  
> netrek.luky.nl at 2592
> 2006-05-20 22:33:32.474 MacTrek[4128] Communication.callServer: got  
> connection parameters
> Current language:  auto; currently objective-c
> Pending breakpoint 1 - ""ServerReader.m:166" resolved
> 2006-05-20 22:33:32.869 MacTrek[4128] ServerSenderTcp.sendBuffer  
> message: CP_SOCKET (27) size: 8
> 2006-05-20 22:33:32.870 MacTrek[4128]  
> LLNotificationCenter.postNotificationName COMM_PICK_SOCKET_SENT
> 2006-05-20 22:33:32.870 MacTrek[4128] ServerSenderTcp.sendBuffer  
> message: CP_FEATURE (60) size: 88
> (gdb) continue
> 2006-05-20 22:33:38.945 MacTrek[4128] ServerReader.readFromServer  
> received message: SP_MOTD (11), count: 1536
> 2006-05-20 22:33:38.994 MacTrek[4128] ServerReader.handlePacket:  
> SP_MOTD: Welcome to Vanilla server version 2.10, patchlevel 2
> 2006-05-20 22:33:39.020 MacTrek[4128]  
> LLNotificationCenter.postNotificationName SP_MOTD
> 2006-05-20 22:33:39.020 MacTrek[4128] ServerReader.readFromServer  
> received message: SP_MOTD_PIC (32), count: 1452
> 2006-05-20 22:33:39.021 MacTrek[4128] ServerReader.handlePacket:  
> SP_MOTD_PIC not implemented
> 2006-05-20 22:33:39.021 MacTrek[4128] ServerReader.readFromServer  
> received message: UNKNOWN (0), count: 1440
> 2006-05-20 22:33:39.021 MacTrek[4128] ServerReader.readFromServer:  
> Unknown packet type. Flushing packet buffer & input stream.
> 2006-05-20 22:33:39.021 MacTrek[4128] ServerReader.readFromServer:  
> Last packet type: 0
>
> roughly the server responds to my CP_SOCKET and CP_FEATURE message  
> with a SP_MOTD and a SP_MOTD_PIC the remainder of the buffer is  
> filled with a 0 and gets flushed. (i might accidently have read an  
> entire frame 1536 in stead of what was really in the buffer but  
> what the hack.
>
>  i was expecting a message SP_S_PLAYER to set which slot i'd been  
> allocated but i might be fully off here.
>
> What is going wrong and what should i have done ?
>
> regards
>
> Chris