Change Ping Response for Traffic Blocked by Access Control List

Access Control Lists (ACLs) are a powerful tool for IT administrators that allow them to control the flow of traffic on their networks. By using an ACL, an administrator can specify which traffic is allowed, and which traffic is blocked. However, in some cases, an administrator may want to change the response of blocked traffic to something other than the default ping response. This article will discuss how to change the ping response for traffic blocked by an access control list (ACL).

The first step to changing the ping response for traffic blocked by an access control list is to determine what type of response is desired. In most cases, the default ping response is a simple “destination unreachable” message, but this can be changed to something more informative. For instance, if the administrator wants to provide more information about why the traffic is being blocked, they could change the response to something such as “traffic blocked by access control list”.

Once the desired response is determined, the next step is to configure the ACL to send the desired response. This involves editing the access list on the router or switch that is controlling the traffic. If the router or switch is using the Cisco IOS, this can be done using the “ip access-list” command. The “deny” statement should be used to block the traffic, and the “reject” statement should be used to send the desired response. The “reject” statement should include the desired response as an argument. For example, if the desired response is “traffic blocked by access control list”, the command should look like this:

ip access-list deny any log reject “traffic blocked by access control list”

Once the command has been entered, the access list should be applied to the interface on the router or switch that is controlling the traffic. This can be done using the “ip access-group” command. For example, if the access list is named “my-acl”, the command should look like this:

ip access-group my-acl in

This will apply the access list to the interface and cause it to send the desired response when a ping is sent to a destination that is blocked.

It is important to remember that when changing the ping response for traffic blocked by an access control list, the response should be kept as simple as possible. Complex responses may be difficult to understand and could cause confusion. Additionally, it is important to remember that the response will only be sent when a ping is sent to a destination that is blocked. If the destination is not blocked, the default ping response will still be sent.

In conclusion, changing the response of blocked traffic to something other than the default ping response can be a useful tool for IT administrators. By carefully configuring an access control list on the router or switch that is controlling the traffic, the administrator can customize the response to something more informative. This can help the administrator better understand the traffic on their network and make informed decisions about which traffic should be allowed or blocked.