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Questions tagged [icmp]

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.

ICMP is not normally used by end-users or to send messages. It's main use is in diagnostics and checking that the network is functioning correctly.

ICMP is just one communications protocol on the web. Others include:

  • Transmission Control Protocol (TCP)
  • User Datagram Protocol (UDP)
  • Hypertext Transfer Protocol (HTTP)
  • Post Office Protocol (POP3)
  • File Transfer Protocol (FTP)
  • Internet Message Access Protocol (IMAP)

ICMP on Wikipedia

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Pinging (ICMP) Docker container on AWS ECS

I've got a script running in a Docker container that listens for ICMP packets. If you ping the container IP address, it picks them up and sends an email. However I'm having a bit of difficulty pinging this container from the outside. The server IP…
StephenC
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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: Kernel IP routing table Destination Gateway …
user13185
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Do NATs rewrite ipAddress in payload of ICMP packets?

Today when I test running a tracert command (windows + Wireshark) I see a outbound ICMP_ECHO_REQUEST packet that has sourceIP as "192.168.1.55" - my local IPAddress. It is followed by a ICMP_TTL_EXCEEDED packet sent from an internet wild host as…
vantrung -cuncon
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Sending Ping at fixed packet size as jumbo frame is not working in linux

I have to hosts connected each other with ipv4 address each other. I modified the MTU of each one to 9000. Then I want to send a Ping request at fixed packet size +1500 to verify that can send and receive jumbo frames. When I send the normal ping I…
JeanCarlos Chavarria
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Why do nping packets with correct MAC and wrong IP do not reach the other container on the same net?

I have a Docker network with two containers in it. When I run nping with a fake target IP address and a real MAC address of the second container, the packets appear in the tcpdump -eni eth0 output with a different source addresses (both MAC and IP)…
Necto
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ICMP DDoS, proper ACL?

We are having about a 3-4Gbps ICMP flood on one of our servers and I wonder.. I have a 20gbps of DDoS protection but the proetction seems ineffective against ICMP funnily (it worked well to block a ton of TCP and UDP attacks in the past yet it fails…
Yannick
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Debian Linux default interface?

I have a Debian machine with an SNMP pooler running, but I am running into an issue with getting the pooler to use a specific interface. The Debian machine has 3 interfaces allow-hotplug eth0 iface eth0 inet static address 10.1.1.3 netmask…
Grant Martin
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centos doesn't reply to icmp request

I have the following situation: Centos7, 2 NIC with following setup: em2(NIC2) : 82.79.24.74/29 82.79.24.75/29 em3(NIC3) : 192.168.0.240/24 192.168.133.240/24 NIC1 and NIC4 are not used. The em2 ips are…
Szilveszter Zsigmond
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What would cause alternating "Request timed out." and "Destination host unreachable." when using ping command?

I am pinging a Windows 8.1 PC that is currently shut down and I'm getting alternating results "Request timed out." and "Destination host unreachable." What could cause this kind of behavior?
Chris76786777
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Did you see similar icmp ever?

ping ya.ru PING ya.ru (213.180.193.3) 56(84) bytes of data. 64 bytes from www.yandex.ru (213.180.193.3): icmp_req=1 ttl=60 time=97.6 ms 64 bytes from www.yandex.ru (213.180.193.3): icmp_req=2 ttl=60 time=96.6 ms 64 bytes from www.yandex.ru…
alterpub
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Linux MIPS box: ICMP (ping) works, but TCP does not - how to fix it?

I'm trying to set up MIPS Linux box network. Here is it's configuration: ~ # ifconfig eth0 Link encap:Ethernet HWaddr CC:5D:4E:FF:45:7F inet addr:192.168.0.2 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr:…
S-trace
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Prevent Linux from processing incoming ICMP Host unreachable packets

I have a test setup with one host on a network (10.1.0.0/16) talking via TCP to another one on another network (10.2.0.0/16) and a gateway in the middle. Sometimes, the TCP connection is lost and while scanning the trace (pcap), I looks like it's…
bbc
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ICMP and traceroute , How does ICMP keep a counter while it passess hops

When tracerouting a destination and going through all these hops, what happens during this process? Does ICMP have an initial counter and decrements this counter on each hop it passes? If the counter is initiated to be 30, how will this work on a…
holasz
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Only ICMP traffic allowed inbound on ISA Server 2006

I have recently set up a connection to a remote site. The connection between the sites is done at the ISP level (ie, this is not a B2B tunnel on ISA). I'm fairly lightweight in the networking realm, so hopefully I can describe this correctly. I…
fireburns
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ICMP rate-limit on time-exceeded messages

How can I set ICMP rate-limiting in a Cisco router? Here on the manual page they only talk about ICMP unreachable messages: ip icmp rate-limit unreachable [df] [ms] [log [packets] [interval-ms]] Is there anything that also includes other ICMP…
Ricky Robinson
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