Q: A support technician uses the ping utility on a system that is online, yet no response is received. What should be allowed through a firewall for ping to operate correctly?
or
Q: When a support technician pings a system that is online, they don’t get a response. What has to pass past a firewall in order for ping to function properly?
- ICMP
- Echo request
- Echo reply
- TTL
Explanation: It is necessary to set up a firewall to let ICMP (Internet Control Message Protocol) Echo Request and Echo Reply messages for the ping program function effectively when it is used behind a firewall. Ping uses ICMP Echo Request messages to determine whether or not a host is reachable, and it uses ICMP Echo Reply messages to determine whether or not the host has responded.
Check to verify that the firewall allows ICMP Echo Request messages to come in and ICMP Echo Reply messages to go out. This may need establishing special rules or permitting ICMP traffic in general, but this will depend on the firewall. Keep in mind that enabling ICMP traffic might be a security issue. Because of this, it is essential to install the required limits by the security regulations that apply to your network.
