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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What is ICMP broadcast good for?

To configure Linux to ignore ICMP broadcasts (to protect from SMURF attacks), I have added the following line to /etc/sysctl.conf: net.ipv4.icmp_echo_ignore_broadcasts = 1 Anyone knows what are the ...
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182 views

Is there a way to test alternate IPv4 routes?

i am using Hurricane Electric's Tunnel Broker service to get IPv6 connectivity. TunnelBroker lets you have access to the IPv6 Internet by using a standard IPv6 tunneling protocol. You send IPv6 ...
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2k views

What are reasons to disallow ICMP on my server?

An EC2 Instance has ICMP services disabled by default. While it's not totally clear to me why, I think it's because it could be a potential security risk. At the moment I'm enabling Echo Responses ...
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What could be causing problems on pinging Windows 8 machines?

Here at my job I have 5 machines with Windows 8 Consumer Preview installed on it. Today I was testing the network conectivity and any of the 5 machines answered to a ICMP ping request(but from another ...
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1answer
1k views

How do I forward traffic between Tun device and eth0?

In summary, I would like to have Tun device traffic forwarded back and forth through another network interface that has internet connection. While I can see the traffic going out to internet ...
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2answers
607 views

ICMP redirect: how to test it with icmpush

I want to see how the routing table changes on a Linux system, when an ICMP redirect is received. For that I use icmpush -v red -sp current-gateway -gw new-gateway -dest google.com -c host -prot tcp ...
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1answer
44 views

ICMP Fails after first packet

I'm trying to ping any ip, other than my LAN IP & localhost, it fails except the first packet!! Snapshot from CMD with the pings But Wireshark capture shows that the ICMP is success!! ...
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2answers
197 views

Traceroute to IP address fails, but traceroute to domain name with same IP address is okay. Why?

When I traceroute to this IP (108.162.198.181) it stops after 1 hop. But tracerouting to a domain (www.gomodule.com) with the same IP shows 9 hops ending in that target. traceroute to ...
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Linux: How to monitor incoming pings

Can I somehow monitor incoming pings on a Linux machine? netcat doesn't seem to support that.
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1answer
97 views

traceroute on Linux displays '* * *'

What is going on? If I run traceroute google.com it outputs 192.168.0.1 for the first router (which is correct) and threee *'s for the rest. I have tried disabling the FireWall on the router ...
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581 views

Firewall blocks ICMP even with Allow rules, even when disbled

Sometime early October (right after update Tuesday???). My Window 7 home machine stopped responding to anything incoming. Effectively breaking iTunes, Sonos, TiVo Desktop, RDP etc. But all those ...
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How is ICMP unique?

I just read this in Wikipedia: Although ICMP messages are contained within standard IP datagrams, ICMP messages are usually processed as a special case, distinguished from normal IP ...
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1answer
67 views

How to inspect DSL router?

There is a DSL connection and a DSL router (Speedport W 701V). After some days or weeks (I didn't record the events) the router makes some problems. Internet connection is ... broken but not ...
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1answer
697 views

Difference between TCP and IP tunnelling?

Can someone please explain in terms of the OSI (or TCP/IP) layers, what is the difference with what goes on when you tunnel IP or TCP, say over the ICMP protocol (although the latter doesnt really ...
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1answer
128 views

ICMP firewall policy for standard ubuntu desktop

For a standard desktop computer running Ubuntu 12.04 behind a NAT router, what ICMP packets should one accept in the firewall, say iptables? It seems there is often conflicting advice; some say block ...
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1answer
99 views

OS X: how to make it reply to “ICMP time stamp query”?

As per another question, I'm using hping--icmp-ts to send the ICMP time stamp requests to debug asymmetric routes. It seems like my OpenBSD box generates time stamp replies by default without any ...
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159 views

Is it allowed to Ping Backbones or other ISP Servers for a prolonged pingtest? [closed]

I made a few Ping tests until now, once I made it a whole week, but now I'm not so sure about the thoughts of the Admins which are owning the servers I ping. Now, I have found a few posts which are ...
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2answers
349 views

what is type of ICMP packets? TCP or UDP

ping packets is a type of ICMP packets.Is there any relation between ICMP with TCP.In other can we guaranty their arrival in the network I want to know ICMP packets in the network is tcp or udp or ...
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1answer
2k views

Is it possible to tunnel ICMP over TCP?

I don't want to tunnel TCP over ICMP (as ptunnel does), I want to go the other way around. I'm in the situation where I have TCP (HTTP) connectivity to a machine but an internal firewall over which I ...
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3answers
185 views

How to use ICMP to verify the accessibility of a site?

If I want to know for sure that a web site is really blocked by the authorities or the site itself faking it, what kind of a method can I use..? I mean that when we use tracer it just use the ICMP... ...
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1answer
504 views

How can I block ICMP/PING/Traceroute on Mac OSX Server?

I understand that on Linux I do: // allow echo 1 >/proc/sys/net/ipv4/icmp_echo_ignore_all // block echo 0 >/proc/sys/net/ipv4/icmp_echo_ignore_all // permanent block (edit /etc/sysctl.conf) ...
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2answers
448 views

test of ICMP block

In my bash scripts I have been using something like: until fping -u google.com; do echo "$0[$$] Network/DNS down?? $(date)" 1>&2 && sleep $(($RANDOM%(1 + ++trynum * 1) +1)).222; done ...
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Why does Windows use the same identifier for different ping sessions?

I noticed while debugging some NATing issues at work that Windows (Windows 7 in this case) echo reply and echo responses are always setting the ICMP identifier field to the same value regardless of ...
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63 views

Wireshark Capture Filter

I am new to wireshark and I am trying to capture an ICMP packet over 802.11g, I am using windows and pingplotter. The issue is that on wireshark capture I am not getting any ICMP packets no matter how ...
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15 views

Make ICMP exempt from IPSec protection

I'm reading a reference book on Microsoft DirectAccess. It contains the quote: To use Ping as a troubleshooting tool, ensure that Internet Control Message Protocol (ICMP) is exempt from IPSec ...
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Ping works, TraceRt is intermittent [duplicate]

When contacting any somewhat remote IP outside my ISP's network, their edge router (hop 5 in my case) shows partial failures (perhaps 3-4 out of 5 attempts generate *'s), but PING traffic goes through ...
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34 views

ICMP over protected wifi

I am looking at sending a single ICMP message to a server and recieving one single ICMP reply. The question that I'm trying to answere is if it is possible to send an ICMP ping over a wifi that i do ...
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52 views

Conditions that trigger a TTL-exceeded ICMP reply

I use traceroute to send udp packets with TTL=1 traceroute -U -p 5000 138.96.116.9 -m 1 -q 1 I can get TTL-exceeded ICMP reply. Then I wrote a program to send a udp packet with TTL=1, but I ...
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271 views

How to setup ICMP or DNS tunnel

I have only one PC, so I can't setup my own server for tunneling. Is there any server around world to help to setup my tunnel, or any free server available around the world which gives me permission ...
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1answer
352 views

Why am I having trouble using ptunnel to connect to machine in DMZ from WAN?

I'm trying to have a play with ptunnel, I have it running (listening) on my raspberry pi in my DMZ and I can connect to it from my LAN and tunnel ssh over it, but I can't get it to work over my LAN. ...
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66 views

Windows ping - 'ignores' ping replies

I'm using Window's built-in ping command to test connectivity with my Ethernet device ( a enc28j60 Ethernet controller and an avr atmega), but Windows ignores replies. Screenshots :- ...
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882 views

Filter ICMP packets sent from my IP address in Wireshark with the Packet Filter

I want to filter the ICMP packets sent from my IP address in Wireshark. I tried the following expression: ip.src == xxx.xxx.xxx.xxx && icmp But the problem is that it shows packets with ...
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1answer
498 views

ICMP Tunnelling IP vs Tunnelling TCP?

Could someone please explain the difference between tunnelling IP data using ICMP packets and tunnelling TCP data via ICMP? Obviously I know this is going to be something relevant to the different ...
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1answer
916 views

Process does ICMP port scan on my OSX box and I am afraid my Mac got a virus

I noticed that my 10.6.6 box has some process sending out ICMP messages to "random" hosts, which concerns me a lot. when doing a tcpdump icmp I see a lot of the following 15:41:14.738328 IP macpro ...