Blocking access to a specific host

Unanswered Question
Feb 4th, 2009

Hi,

I have point-2-point link between our branch office to head-quarter...

We want to block access to a specific hosts at Head-Quarter from Branch-office.

But we have multiple VLANS at Branch-office

How could we block access to this host ??? The Host is a Server [Two Servers ]

I have this problem too.
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pstebner10 Wed, 02/04/2009 - 07:17

You can put an acl in place on your edge interface denying traffic to those hosts. For example, if you have a PIX/ASA, you could do:

access-list outside_in extended deny ip any host

access-list outside_in extended deny ip any host

access-group outside_in in interface outside

HTH,

Paul

ronald.ramzy Wed, 02/04/2009 - 09:31

its a 3550 switch

to start with I need 3 VLANS to block these hosts.

what command is required on the VLAN to block these hosts.

pstebner10 Wed, 02/04/2009 - 09:44

Ronald-

Are you using the 3550 in Layer3 mode? What is the topology on each end?

Paul

pstebner10 Wed, 02/04/2009 - 11:05

Ronald-

You can apply an access-list to the uplink port of the 3550. I assume that you have the uplink at L3 and the rest as switchports since you mentioned 3 VLANs. Can you post your config?

Paul

Mohamed Sobair Wed, 02/04/2009 - 11:12

Hi,

U can do that by configuring the following on the Switchport:

"Switchport mode protected", this will eleminate access to the host reside on the port.

HTH

Mohamed

ronald.ramzy Wed, 02/04/2009 - 13:17

Users are located on Different location in the Building so I feel restricting on trunks are not easy....

Mohammed please ellaborate more on Swithcport mode protected... how to configure this for my scenario.....

Kindly advice on the config

The Vlan I wanna restrict is

VLAN 100

int vlan 100

description BLOCK C VLAN

ip address 172.16.1.0 255.255.255.0

ip access-group Restrict-ATARI

ip access-list extended Restrict-ATARI

deny ip 172.16.1.0 0.0.0.255 host 192.168.1.222

permit ip any any

Mohamed Sobair Wed, 02/04/2009 - 13:33

So, you want to deny access at layer-3 using access-list.right?

Could u please tell in which vlan the Host reside? what 192.168.x.x represent? Do u want to deny access from 172.x subnet toward the host? pls clarify more..

Thanks,

Mohamed

ronald.ramzy Wed, 02/04/2009 - 14:38

User VLan is VLAN 100

Server1 : 192.168.1.222

Server2 : 192.168.1.111

I want to restrict user-vlan 100 from accessing the Server1 && Server2 only and permit others.

{ description in VLAN 100 " BLOCK C VLAN " means Building-C )

Leo Laohoo Wed, 02/04/2009 - 19:18

Access list should be applied nearest the server(s):

access-list 101 deny ip 172.16.1.0 0.0.0.255 host 192.168.1.111

access-list 101 deny ip 172.16.1.0 0.0.0.255 host 192.168.1.222

permit ip any any

int vlan 100

access group 101 in

ronald.ramzy Wed, 02/04/2009 - 21:57

Thanks for your reply.

I would like to understand what is the technical difference or benefits on applying the ACL near the Server or applying the ACL on User-VLAN.

Appreciate your help.

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