From: Brian Dennis (brian@labforge.com)
Date: Tue Jun 17 2003 - 00:29:15 GMT-3
Telnet will not originate from port 23. Think about it like this. If you
are using TCP port 23 as a source port for Telnet on R1, what will
happen when someone tries to telnet to R1?
I would highly recommend reading one of the following books.
Internetworking with TCP/IP Vol.1: Principles, Protocols, and
Architecture (4th Edition) by Douglas Comer
The Protocols (TCP/IP Illustrated, Volume 1) by W. Richard Stevens
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Jason Cash
Sent: Monday, June 16, 2003 8:08 PM
To: ccielab@groupstudy.com
Subject: Extended ACL clarification.
A certain instructs:
Config R2 such that all telnet traffic sourced from the lo0 of R1 and
destined for the 172.29.80.0 subnet, will go thru R5.
R1 - Lo0 192.168.1.1/32
R2 - S0 172.29.100.2
R5 - S0 172.29.100.5
R1(e1)-----(e0)R2(s0)-----(s0)R5
My question is, is the following incorrect and does it accomplish the
same
thing as the solution:
interface Ethernet0
description to R1 E0 (crossover)
ip address 172.29.12.2 255.255.255.192
ip policy route-map local23
!
route-map local23 permit 10
match ip address 100
set ip next-hop 172.29.100.5
!
access-list 100 permit tcp host 192.168.1.1 eq telnet 172.29.80.0
0.0.0.31
The solution provided was:
access-list 100 permit tcp host 192.168.1.1 172.29.80.0 0.0.0.31 eq
telnet
I guess I want to know the difference between the two. Would My
solution
provide the same result. I interpret mine to mean:
allow traffic from host 192.168.1.1 (tcp src. port 23) to goto subnet
172.29.80.0/27
I interpret the solution as:
allow traffic from host 192.168.1.1 to goto subnet 172.29.80.0/27 (tcp
dest.
port 23)
What ais the difference? Does telnet not originate from port 23 on
occasion? Is this where the problem would come into play. I get
confused
on src/dest. ports so any links to clear the confusion would be
appreciated.
This archive was generated by hypermail 2.1.4 : Fri Jul 04 2003 - 11:10:59 GMT-3