[2233] in linux-net channel archive
tcp changes ?? NCSA telnet doesn't work any more !!!
daemon@ATHENA.MIT.EDU (Jacek Zapala)
Sun Mar 24 18:41:54 1996
Date: Mon, 25 Mar 1996 00:11:39 +0100 (MET)
From: Jacek Zapala <jacek@deuter.im.pw.edu.pl>
To: linux-net@vger.rutgers.edu
I have found that linux 1.3.74 and 1.3.77 does not work with NCSA telnet for
DOS (or rather NCSA telnet doesn't with linux). From NCSA side it looks like
the conection is open, but nothing (even login's output) arrives. From the
linux side in.telnetd is launched, but nothing more.
netstat -o:
Active Internet connections
Proto Recv-Q Send-Q Local Address Foreign Address (State)
User
tcp -1 24 jacka:telnet lenki:12115 ESTABLISHED
root on (32.95/10)
Active UNIX domain sockets
Proto RefCnt Flags Type State Path
unix 2 [ ] SOCK_STREAM UNCONNECTED /dev/log
unix 2 [ ] SOCK_STREAM UNCONNECTED /dev/log
tcpdump -v:
21:52:31.000000 lenki.12115 > jacka.telnet: S 250949632:250949632(0) win
1024 <mss 1500> (ttl 100, id 1)
21:52:31.000000 lenki.12115 > jacka.telnet: P 250949633:250949648(15) ack
4024216418 win 1024 (ttl 100, id 2)
21:52:33.000000 lenki.12115 > jacka.telnet: P 0:15(15) ack 1 win 1024 (ttl
100, id 3)
21:52:33.000000 lenki.12115 > jacka.telnet: . ack 1 win 1024 (ttl 100, id 4)
21:55:18.000000 lenki.12115 > jacka.telnet: . ack 1 win 1024 (ttl 100, id 5)
21:58:03.000000 lenki.12115 > jacka.telnet: . ack 1 win 1024 (ttl 100, id 6)
...........
lenki is a dos machine running NCSA telnet 2.3.07 on a packet driver
jacka is a linux machine
both on a local network
I have only these two computers at home so I can present only one-way
communication (or there is a way to make tcpdump display both-way
communication, but I can't find it).
With linux 1.2.13 it looks like:
19:43:02.000000 lenki.3773 > jacka.telnet: S 208392192:208392192(0) win 1024
<mss 1500> (ttl 100, id 1)
19:43:02.000000 lenki.3773 > jacka.telnet: P 208392193:208392208(15) ack
549586513 win 1024 (ttl 100, id 2)
19:43:02.000000 lenki.3773 > jacka.telnet: P 15:18(3) ack 4 win 1024 (ttl
100, id 3)
19:43:02.000000 lenki.3773 > jacka.telnet: P 18:45(27) ack 25 win 1024 (ttl
100, id 4)
19:43:02.000000 lenki.3773 > jacka.telnet: P 45:56(11) ack 31 win 1024 (ttl
100, id 5)
19:43:02.000000 lenki.3773 > jacka.telnet: P 56:65(9) ack 40 win 1024 (ttl
100, id 6)
19:43:02.000000 lenki.3773 > jacka.telnet: . ack 852 win 1024 (ttl 100, id 7)
19:43:02.000000 lenki.3773 > jacka.telnet: . ack 855 win 1024 (ttl 100, id 8)
19:43:02.000000 lenki.3773 > jacka.telnet: . ack 868 win 1024 (ttl 100, id 9)
I have tested this with 1.3.74 kernel with forwarding and masquerading
option enabled and disabled and on 1.3.77 with:
TCP/IP networking (CONFIG_INET) [Y/n/?]
IP: forwarding/gatewaying (CONFIG_IP_FORWARD) [Y/n/?]
IP: multicasting (CONFIG_IP_MULTICAST) [N/y/?]
IP: firewalling (CONFIG_IP_FIREWALL) [Y/n/?]
IP: accounting (CONFIG_IP_ACCT) [N/y/?]
IP: optimize as router not host (CONFIG_IP_ROUTER) [N/y/?]
IP: tunneling (CONFIG_NET_IPIP) [N/y/m/?]
IP: firewall packet logging (CONFIG_IP_FIREWALL_VERBOSE) [Y/n/?]
IP: masquerading (ALPHA) (CONFIG_IP_MASQUERADE) [Y/n/?]
*
* (it is safe to leave these untouched)
*
IP: PC/TCP compatibility mode (CONFIG_INET_PCTCP) [N/y/?]
IP: Reverse ARP (CONFIG_INET_RARP) [N/y/m/?]
IP: Disable Path MTU Discovery (normally enabled)
(CONFIG_NO_PATH_MTU_DISCOVERY) [N/y/?]
IP: Disable NAGLE algorithm (normally enabled) (CONFIG_TCP_NAGLE_OFF)
[N/y/?]
IP: Drop source routed frames (CONFIG_IP_NOSR) [Y/n/?]
IP: Allow large windows (not recommended if <16Mb of memory)
(CONFIG_SKB_LARGE) [N/y/?]
The same NCSA telnet configuration works with 1.2.13 kernel.
Do you have any ideas ?
I will try with 'Drop source routed frames' set to NO in a moment, but I'm
almost sure it won't change anything ........
[45 minutes later]
I was absolutely right. I don't try setting 'PC/TCP compatibility mode' to
YES, because I'm absolutely sure I have never set it in 1.2.13.
If you have any ideas or need additional information or testing, feel free
to write me even at 8 in the morning :-)
Jacek Zapala
