Q & A on ICMP "Connection refused" message Q: Is the "Connection Refused" error message implemented using ICMP? A: An application receives "connection refused" as one possible error return code when it tries to connect a TCP socket to a remote system; the application then prints the message for the user. You are correct that ICMP is used to send the error message from the remote system back to the local system. The specific ICMP error message is "destination unreachable" with the specific cause specified as a "port unreachable". Q: I like your new edition -- especially the part on cable modems and ADSL :--). A: Thanks, and thanks for your help with that section.