ICMP stands for Internet Control Message Protocol. It is primarily used by the operating systems of networked computers to send error messages indicating service status.

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Ping issues with Windows Server 2008 R2 with mail server!

For some reason I can ping all servers in my network except for the mail server and the mail server can ping all servers except the windows server 2008 R2. The firewall has been disabled and still it ...
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Why isn't ICMP routing with iptables nat routing

I'm using iptables on Ubuntu server to route a public IP to a private IP. I want to nat all traffic, including 80, 443 and ICMP. However, it appears that ICMP isn't routing. I have a steady ping ...
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How to make Windows honour an ICMP Connection Refused message after a TCP connection attempt

We have a tool which is used to manage a server process remotely over TCP. One of the tools features is to check if the server is running by attempting to connect to the server in a loop for a given ...
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Why not block ICMP?

I think I almost have my iptables setup complete on my CentOS 5.3 system. Here is my script... # Establish a clean slate iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT ...
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Strange: why does linux respond to ping with ARP request after last ping reply?

I (and a colleague) have just noticed, and tested, that when a Linux machine is pinged, after the last ping it initiates a unicast ARP request to the machine that initiated the ICMP ping. When pinging ...
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Why is network stack ignoring icmp replies from non-default interface?

I have following situation: eth0 - default gateway ( ip: 172.28.183.100, gw: 172.28.183.1 ) eth0 - secondary network connection ( ip: 172.28.171.2, gw: 172.28.171.2). routing looks like this: ...
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Why block outbound ICMP?

This question is slightly related to "Why Block Port 22 Outbound?". I don't see how this can be a notable security risk.
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How to properly interpet the results of tracert, in particular the second to last hop before a timeout

I am troubleshooting a wireless internet connection that is continuously dropping. The isp says the radio signal is good so it must by my cisco asa 5505. I don't believe them... For discussion ...
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How do you allow ICMP Echo Requests on a Cisco ASA 55xx Router?

I'm very new to managing Cisco equipment, so bear with me. I'm configuring a Cisco ASA 5505 router for my office, and I am reasonably competent enough with the console to configure the basics -- our ...
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ping -f shows problems but regular ping doesn't

I have a strange issue, hosting at Softlayer Washington data center. Test from an EC2 instance to my server at Softlayer :- [root@EC2-box ~]# ping -f -c 100 MY-SL-BOX PING MY-SL-BOX (MY-SL-BOX) ...
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Ping command is not accepted if firewall is on at remote system

I am using ping command to know whether remote machine is on or not. But problem is that ping command (ICMP Packect) is not accepted at remote machine if firewall is on and it assumed that remote ...
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Server with slow ping response

Two boxes with identical loads serving the same sites tend to slow down and stop responding to ping. The slow (or intermittent) ping causes our load balancer to think the servers are offline and ...