 Lab Simulation){kind=link}
Lab Simulation Question – ACL-1
A network associate is adding security to the configuration of the Corp1 router. The user on host C should be able to use a web browser to access financial information from the Finance Web Server. No other hosts from the LAN nor the Core should be able to use a web browser to access this server. Since there are multiple resources for the corporation at this location including other resources on the Finance Web Server, all other traffic should be allowed.
The task is to create and apply an access-list with no more than three statements that will allow ONLY host C web access to the Finance Web Server. No other hosts will have web access to the Finance Web Server. All other traffic is permitted.
Access to the router CLI can be gained by clicking on the appropriate host.
All passwords have been temporarily set to “cisco“.
The Core connection uses an IP address of 198.18.196.65
The computers in the Hosts LAN have been assigned addresses of 192.168.33.1 – 192.168.33.254
Host A 192.168.33.1
Host B 192.168.33.2
Host C 192.168.33.3
Host D 192.168.33.4
The servers in the Server LAN have been assigned addresses of 172.22.242.17 – 172.22.242.30
The Finance Web Server is assigned an IP address of 172.22.242.23.
Answer:
Corp1>enable Corp1#configure terminal Corp1(config)#access-list 100 permit tcp host 192.168.33.3 host 172.22.242.23 eq 80 Corp1(config)#access-list 100 deny tcp any host 172.22.242.23 eq 80 Corp1(config)#access-list 100 permit ip any any Corp1(config)#interface fa 0/1 Corp1(config-if)#ip access-group 100 out Corp1(config-if)#end Corp1#copy running-config startup-config
Explanation:
Corp1> enable Password: cisco
We should create an access-list and apply it to the interface which is connected to the Servers LAN interface, because it can filter out traffic from both Sw-Hosts and Core networks. The Server LAN network has been assigned addresses of 172.22.242.17 – 172.22.242.30 so we can guess the interface connected to them has an IP address of 172.22.242.30 (.30 is the number shown in the figure). Use the “show ip interface brief” command to check which interface has the IP address of 172.22.242.30.
Corp1#show ip interface brief interface IP-Address OK? Method Status Protocol FastEthernet0/0 192.168.33.254 YES manual up up FastEthernet0/1 172.22.242.30 YES manual up up Serial0/0 198.18.196.65 YES manual up up
We learn that interface FastEthernet0/1 is the interface connected to Server LAN network. It is the interface we will apply our access-list (for outbound direction).
Corp1#configure terminal
Our access-list needs to allow host C – 192.168.33.3 to the Finance Web Server 172.22.242.23 via web (port 80)
Corp1(config)#access-list 100 permit tcp host 192.168.33.3 host 172.22.242.23 eq 80
Deny other hosts access to the Finance Web Server via web
Corp1(config)#access-list 100 deny tcp any host 172.22.242.23 eq 80
All other traffic is permitted
Corp1(config)#access-list 100 permit ip any any
Apply this access-list to Fa0/1 interface (outbound direction)
Corp1(config)#interface fa0/1 Corp1(config-if)#ip access-group 100 out
Notice: We have to apply the access-list to Fa0/1 interface (not Fa0/0 interface) so that the access-list can filter traffic coming from both the LAN and the Core networks. If we apply access list to the inbound interface we can only filter traffic from the LAN network.
In the real exam, just click on host C and open its web browser. In the address box type http://172.22.242.23 to check if you are allowed to access Finance Web Server or not. If your configuration is correct then you can access it.
Click on other hosts (A, B and D) and check to make sure you can’t access Finance Web Server from these hosts.
Finally, save the configuration
Corp1(config-if)#end Corp1#copy running-config startup-config
This configuration only prevents hosts from accessing Finance Web Server via web but if this server supports other traffic – like FTP, SMTP… then other hosts can access it, too.
Notice: In the real exam, you might be asked to allow other host (A, B or D) to access the Finance Web Server so please read the requirement carefully.
Modification #1
A network associate is adding security to the configuration of the Corp router. The user on host B should be able to access the Finance Web Server. Host B should be denied to access other server on S1-SRVS network. Since there are multiple resources for the corporation at this location including other resources on the Finance Web Server, all other traffic should be allowed.
The task is to create and apply a numbered access-list with no more than three statements that will allow ONLY host B access to the Finance Web Server. Deny host B from accessing the other servers. All other traffic is permitted.
access-list 100 permit ip host 192.168.33.2 host 172.22.242.23 access-list 100 deny ip host 192.168.33.2 172.22.242.16 0.0.0.15 access-list 100 permit ip any any
Modification #2
A network associate is adding security to the configuration of the Corp1 router. The user on host C should be able to access the Finance Web Server. No other hosts from the LAN nor the Core should be able access this server. All other traffic should be allowed.
The task is to create and apply a numbered access-list with no more than three statements that will allow ONLY host C access the Finance Web Server. No other hosts will have access to the Finance Web Server. All other traffic is permitted.
access-list 100 permit ip host 192.168.33.3 host 172.22.242.23 access-list 100 deny ip any host 172.22.242.23 access-list 100 permit ip any any
Modification #3
A network associate is adding security to the configuration of the Corp1 router. The user on host C should be able to use a web browser to access financial information from the Finance Web Server. Other access from host C to Finance Web Server should be denied. No other hosts from the LAN nor the Core should be able to access the Finance Web Server. All other traffic should be allowed.
The task is to create and apply a numbered access-list with no more than three statements that will allow ONLY host C web access to the Finance Web Server. Also host C should be denied to access any other services of Finance Web Server. No other hosts will
access to the Finance Web Server. All other traffic is permitted. access-list 100 permit tcp host 192.168.33.3 host 172.22.242.23 eq 80 access-list 100 deny ip any host 172.22.242.23 access-list 100 permit ip any any
Modification #4
A network associate is adding security to the configuration of the Corp1 router. The user on host D should be able to use a web browser to access financial information from the Finance Web Server. Other access from host C to Finance Web Server should be denied. No other hosts from the LAN nor the Core should be able to access the Finance Web Server. All hosts from the LAN nor the Core should able to access Public Web Server.
The task is to create and apply a numbered access-list with no more than three statements that will allow ONLY host D should be able to use a web browser(HTTP)to access the Finance Web Server. Other types of access from host D to the Finance Web Server should be blocked. All access from hosts in the Core or local LAN to the Finance Web Server should be blocked. All hosts in the Core and local LAN should be able to access the Public Web Server.
access-list 100 permit tcp host 192.168.33.3 host 172.22.242.23 eq 80 access-list 100 deny ip any host 172.22.242.23 access-list 100 permit ip any any