Abreviation of Internet Control Message Protocol. The protocol allows for the return propagation of error messages related to IP packets. ICMP is critical to basic network tools like ping and traceroute.

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When should I drop a packet with ICMP type 3, code 9 or 10, TCP RST, or TCP ACK?

This answer says there are a few ways of dealing with a blocked packet at a firewall: At each of these levels a 1st IP packet (and any other protocol packet as an ESP or AH packet) might receive ...
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2answers
81 views

Promiscuous mode and packet sniffing

Is it must for a packet sniffer to enable promiscuous mode?Can packets be sniffed without the NIC being in promiscuous mode? Also when in promiscuous mode the NIC accepts all packets which are not ...
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2answers
114 views

Is there any reason that captive portal server can't block the ICMP echo request/reply packet

We can get connected to those public WiFi hotspot without the account but can access to no website but the login page. As I tested, all those login website would respond to my ping even I was an ...
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1answer
69 views

localhost to localhost ICMP traffic that is suspicious.. any idea of what is creating this?

I keep seen this on my tcpdump output.. is prob something very simple and logical but I can't see to see any process with lsof or netstat doing a ICMP request to it's own 127.0.0.1 every 2-3 secs... ...
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4answers
592 views

Security risk of allowing ICMP “destination unreachable” packets on AWS

If I configure an Amazon AWS VPC, should I explicitly allow ICMP "destination unreachable" packets inbound? I am wanting the VPC firewall to block everything by default, however does this mean this ...
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1answer
99 views

For what is an ICMP tunnel useful and how does ist work?

For what is it usefull? I (client) send an echo-request (with http data) to the proxy server. Then the proxy has to send me the echo-reply. But my question now is: 2.1 The proxy first needs to send ...
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1answer
837 views

Block Packets in snort

In rules Configuration of snort , this is allowed: alert tcp any any -> any any (msg:"HTTP Connection"; react:block;) however when I write this is allowed: alert icmp any any -> any any ...
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3answers
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Computer sending unstopped ICMP echo request to an IP

I noticed while hanging in Microsoft Network Monitor that my computer is sending ICMP echo request to an arbitrary IP address 202.39.253.11. I looked for the owner of this IP and I found it is owned ...
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1answer
230 views

Why is ICMP timestamping disabled on OS X?

It would seem like ICMP timestamping is quite a useful feature for troubleshooting networks with asymmetric paths. Replies to icmp(4) timestamp requests are generated by the kernel: On OpenBSD, the ...
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1answer
468 views

Disabling Ping/ICMP Requests [duplicate]

Are there any benefits from disabling Ping/ICMP requests on servers? I've read where people say to do it but I can't seem to find any real benefits with it. Only more likely to cause more problems. ...
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1answer
2k views

Wireshark Gratuitous ARP

I'm playing around with scapy and wireshark and I have sent a packet to a destination that does not exist (10.0.2.14). Wireshark shows an ARP attempt to resolve the address but as its not there the ...
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1answer
446 views

how to handle error reply messages?

For security reasons, many organizations do not allow error reply messages to leave their internal Internets. How, specifically, could hackers use information in echo reply messages to learn about the ...
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Is it a bad idea for a firewall to block ICMP?

This question was inspired by this answer which states in part: The generic firewall manifest file finishes off by dropping everything I didn't otherwise allow (besides ICMP. Don't turn off ICMP). ...
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2answers
186 views

IP attack by reading/writing data?

If I remember correctly there is an ICMP attack whereby you can embed malicious code and it gets read/executed, causing the problem (similar to SQL injection). Are there any further/more dangerous ...
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3answers
2k views

Is there any risk in allowing ping packets *out* through a firewall

The company I'm currently doing work for does not allow ping requests out through their firewall, for "security reasons" and I'm baffled as to why this is a concern. Before you point me to (e.g.) ...
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0answers
234 views

AD authentication with high amount of ICMP traffic [closed]

We have an IPS in place and it's constantly triggering ICMP / Ping flood signatures between workstations and AD server; or AD to workstation. I understand that ICMP is used for AD authentication. ...
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1answer
340 views

Differentiate normal flow and broadcast attacks

How do you identify whether a broadcast traffic is normal or is considered an attack such as a DoS attack?, There is some information that the plot or the source that allows me to differentiate ...
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2answers
932 views

ICMP redirects and source routing in the wild?

Theoretically, ICMP redirect messages (IPv4 and IPv6) and source routing (IPv4) / routing headers (IPv6) are very dangerous. However, I'm curious as to if attacks using these features really work in ...
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6answers
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Security risk of PING?

I have been told that PING presents a security risk, and it's a good idea to disable/block it on production web servers. Some research tells me that there are indeed security risks. Is it common ...