Shawn,

 

It should say to drop on that I may have just not pasted the drop in there
for telnet.  As telnet and ssh are the only VTY protocols what is shown
should be fine if the drop keyword was there.

 

Regards,

 

Tyson Scott - CCIE #13513 R&S and Security

Technical Instructor - IPexpert, Inc.


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From: [email protected]
[mailto:[email protected]] On Behalf Of Shawn H.
Mesiatowsky
Sent: Thursday, June 11, 2009 9:39 PM
To: [email protected]
Subject: [OSL | CCIE_Security] Lab 6.3, PortFiltering

 

In Lab6.3, you have a request to allow r5 and r6 to only allow inbound ssh.

 

Here was your config

 

class-map type port-filter Task63

 match port tcp 23

policy-map type port-filter Task63

 class Task63

control-plane host

 service-policy type port-filter input Task63

 

This should allow telnet, and since no drop method is specified, all other
protocols are allowed as well. I tested this, and I was able to telnet from
any device to R5 and R6. Here is my config I used:

 

class-map type port-filter match-any CM_portfilter

 match not  port tcp 22

policy-map type port-filter PM_portfilter

 class CM_portfilter

   drop

control-plane host

 service-policy type port-filter input PM_portfilter

 

This drops all traffic except SSH, which is what the lab requested. I also
tested this and it works.

Just on a side note from past experience, I was playing with the match
closed-ports command, and I found an interesting thing

 

When you are using stateful nat without hsrp, the routers communicate with
one another over a specific port. This communication will be blocked when
using the closed-port command. The interesting thing here is that this is
not a closed port, as it is listed in the listening ports when executing the
show control-plane host open-ports (possible bug?). This was in 12.4(15)T:

 

class-map type port-filter match-any CL_portfilter

 match closed-ports

policy-map type port-filter PM_portfilter

 class CM_portfilter

   drop

control-plane host

 service-policy type port-filter input PM_portfilter

 

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