From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Mon Jun 12 2006 - 16:48:03 ART
Hi There Sami,
by RFC: 793
For a connection to be established or initialized, the two TCPs must
synchronize on each other's initial sequence numbers. This is done in an
exchange of connection establishing segments carrying a control bit called
"SYN" (for synchronize) and the initial sequence numbers
So debugging this in the router:
IP: s=192.10.1.3 (local), d=192.10.1.254 (Ethernet0/0), len 44, sending
TCP src=21994, dst=23, seq=1223489462, ack=0, win=4128 SYN :::(1
PKT):::
IP: s=192.10.1.254 (Ethernet0/0), d=192.10.1.3 (Ethernet0/0), len 44, rcvd 3
TCP src=23, dst=21994, seq=4176947662, ack=1223489463, win=4128 ACK SYN
:::(2 PKT):::
IP: s=192.10.1.3 (local), d=192.10.1.254 (Ethernet0/0), len 40, sending
TCP src=21994, dst=23, seq=1223489463, ack=4176947663, win=4128 ACK
:::(3 PKT):::
Also you can try this links
http://en.wikipedia.org/wiki/Image:TCP_state_diagram.png
http://en.wikipedia.org/wiki/Transmission_Control_Protocol#Connection_establ
ishment
http://www.onlamp.com/pub/a/bsd/2001/03/26/FreeBSD_Basics.html
HTH
Victor.
-----Mensaje original-----
De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de Sami
Enviado el: Lunes, 12 de Junio de 2006 02:00 p.m.
Para: Cisco certification
Asunto: Telnet
Group,
This is basic question but still I have problem in understanding it ,what is
the difference between
permit tcp any eq telnet any
or
permit tcp any eq telnet any established
I think both should allow telnet connection to come in ...am I correct ?
Thanks
This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:32 ART
