Why is there no response to my ICMP request?
I tried ping 192.168.1.62 from server1, according to tcpdump on server3, ICMP request is received, but it doesn’t generate ICMP response. I was receiving ICMP packets but did not see them go out. The problem was related to the traffic traversing multiple interfaces and reverse path filtering being on by default…
Why is my computer not responding to my Ping?
If it won’t respond to PING on a local network (ethernet, usually), then it could be a Firewall setting. I assume you are running Windows? In Windows XP, you can disable/enable ICMP packets. When you PING it sends an ICMP packet, which some some firewalls will filter.
Is there an ICMP response in CentOS server2?
Closed 2 years ago. I set up 3 CentOS servers, configured server2 as router between 192.168.1.0/24 and 30.0.0.0/24, but ping can’t get through. I tried ping 192.168.1.62 from server1, according to tcpdump on server3, ICMP request is received, but it doesn’t generate ICMP response. I was receiving ICMP packets but did not see them go out.
What kind of packet does a ping send?
When you PING it sends an ICMP packet, which some some firewalls will filter. If you are using the Windows firewall, it depends on the version of Windows you are running.
What to do with a Linux ICMP request?
Then there are several options for what to do with them… I’m enabling loosely handling them: Run tcpdump with -e flag and see if the destination MAC address is correct. Not the answer you’re looking for?
Do you have to return data to ICMP echo message?
Hmm, RFC 792 says on page 15: “The data received in the echo message must be returned in the echo reply message”. If not, the checksum will be different, which is part of the key to match the ICMP echo requests and responses. If there’s a valid reason to limit the payload size (e.g. anti DDOS), it may be needed to tweak the PDU matching code.