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 the purpose of using a large ping packet?

While analyzing some traffic logs, I noticed a node pinging its gateway with a large ping packet size, ranging from 700 bytes to 1 MB. It's a constant ping from node to gateway and the size per ping ...
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2answers
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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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2answers
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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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3answers
9k views

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
318 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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4answers
10k 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 ...
4
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1answer
17k views

What could be causing problems on pinging Windows 8 machines?

Here at my job I have five machines with Windows 8 Consumer Preview installed on it. Today I was testing the network conectivity and any of the five machines answered to a ICMP ping request (but ...
3
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2answers
393 views

Linux Virtual machine can't ping Google, while Host can do it

Assumptions: You have a Windows 7 Ultimate as your host. You have a Linux Kali 2 as a VMWare Workstation virtual machine on this host. Your network adapter is bridged on the VMWare(Version 10.0.3). ...
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1answer
6k 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 and ...
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2answers
2k 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 ...
3
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1answer
69 views

Varying TTL on LAN

I've got a wireless router behind a router-modem. If I ping my router-modem (TWO hops), all seems well : robut@host:~$ ping 172.X.X.36 PING 172.X.X.36 (172.X.X.36) 56(84) bytes of data. 64 bytes ...
3
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1answer
133 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
323 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 www.gomodule....
2
votes
1answer
119 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 (192.168....
2
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1answer
410 views

Cannot ping or ssh from lan to virtual machine

I have next setup: My home lan = 192.168.1.0/24 My virtual lan = 192.168.207.0/24 My laptop = 192.168.1.109 (dhcp OS=Windows7) My desktop = 192.168.1.206 (fixed ip OS=Windows8) My virtual machine ...
2
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1answer
778 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. ...
2
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0answers
1k 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 ...
2
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1answer
823 views

SSH and PWNAT for SSH Connection Between Two Separate NATs

Is it possible to use pwnat and SSH to establish a "peer-to-peer" SSH connection between two machines that are behind two separate firewalls/NATs? If this is possible, what are the steps that would ...
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1answer
3k views

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 processing,...
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1answer
211 views

Can a home PPPoE connection access all websites, regardless of the site infrastructure's MTU settings?

I'm just trying to get my head round MTU, MRU and MSS. My interest initially came from the answer in this post: Security risk of PING?: Some ICMP packet types MUST NOT be blocked, in particular ...
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1answer
93 views

How to inspect DSL router? [closed]

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
2k 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
44 views

Disable ping on Windows (not block)

How can I disable Windows ping from replying? Is there a service I can kill? I don't want to block it via a firewall, as I can my own ping service running (custom application). tia.
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2answers
360 views

Why does a ping flood wake up a PC, while a single ping does not?

I just noticed that when you flood-ping a PC that is in sleep-mode, it will wake it up while a single ping or multple pings per 1 sec does not wake it up. Wake up on lan/wan is enabled. What is the ...
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1answer
563 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
87 views

Exact meaning of ICMP protocol 1 port xxx unreachable in a ping exchange

A tcpdump of a ping session shows the following two lines: IP gateway.comp.com > somehost.comp.com: ICMP redirect 10.8.0.10 to host othergateway.comp.com, length 68 IP gateway.comp.com > ...
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1answer
28 views

Why does ICMP Echo Request and Echo Reply packets contain a Data portion?

The ICMP Echo Request and Echo Reply packets contain a Data portion. For example this is an Echo Request packet (that was sent in Windows using the ping command): As you can see, there is a Data ...
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62 views

ICMP flood with ping working only one time

my problem is simple: The first time I made a flooding ping to a fake ip on my network (for testing if someone is on promisc mode), it works perfectly: $ping -f 192.168.1.10 After perfoming this, ...
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1answer
206 views

UDP port scanning

UDP is connectionless, so I can't expect a response packet, necessarily. If the port is closed, I might get an ICMP error message, but if the firewall could silently drop the ICMP packet How could I ...
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0answers
2k views

udp client sending ICMP “port unreachable” when receiveing messages from the server

(Note: I moved this question from StackOverflow, because it's to be considered off-topic there, better fits here, and still unsolved) I have a udp client using luasocket, basically doing this (with a ...
1
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2answers
445 views

Batch Capture incoming Netstat IPs as variable

I'm trying to figure out if there is a way I can capture (and if possible, log) the ip addresses displayed from 'netstat' command. I'm trying to make a script that waits for a ping from a specific ...
1
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1answer
341 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 ...
0
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1answer
666 views

Router keep advertising itself on ipv6

I keep receiving the following router advertisement every few seconds from my router on ipv6 despite disabling my wireless ipv6 connection: # tcpdump -vv 'ip6 and icmp6' tcpdump: listening on wlth0, ...
0
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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 ...
0
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3answers
377 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... ...
0
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1answer
32 views

Why is the ICMP protocol considered to run at layer 3 when it is a payload for the IP packet?

Why is the ICMP protocol considered to run at layer 3 on the wikipedia page ? (same layer as IP) when the ICMP protocol data is a payload of the IP packet? this is the article on wikipedia that ...
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3answers
676 views

How ping a server which has ICMP blocked

I'm trying to ping a server which has ICMP blocked with normal ping. It's showing: Request timed out Is there any other method to ping it?
0
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1answer
144 views

Can I ping a host that has disabled the ICMP Ping option?

I need to know if it's possible to compare and test how fast is an IP (ie: any web or game server) relative to my location (in terms of network latency), even if they have disabled ICMP/Ping requests ...
0
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1answer
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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) ...
0
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2answers
935 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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0answers
18 views

Linux kernel ignoring ICMP redirect requests, but only sometimes

With tcpdump I can verify that ICMP redirect requests are honoured when using ping, but not when using ssh. Here is the setup: myhost connects to otherhost. otherhost has tcpdump running. It has a ...
0
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0answers
17 views

How to use socket or raw socket to sniff all icmpv6 nd packets?

I am working on NDP(neighbor discover protocol) on a router host and the ndp proxy functions to advertise neighbors behind the same router host. But currently, got stuck with the socket to sniff ...
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0answers
26 views

How do PING responses disabled from different subnets?

I found that: I can ping my Windows box A from another computer B in the same subnet. This implies, that echo server is running. I can open remote desktop on A from another computer C in another ...
0
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0answers
276 views

Why can't i ping my iPad from the PC?

I have an iPad 2 with iOs 8.3 and i have a PC with Win 7. And i have a trouble: the PC can't ping the iPad. 'ping 192.168.0.41' says 'destination host unreachable' But my gate device, ZTE F660 can ...
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68 views

Traceroute behind a Carrier-Grade NAT (IP address 100.64.0.0/10)

Is it possibile that a Carrier-Grade NAT blocks all incoming ICMP messages? Trying a traceroute from an IP address belonging to the range 100.64.0.0/10 it doesn't detect any hop, neither the first ...
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418 views

how to stop PC from sending ICMP of “Destination Unreachable(host administratively prohibited)”

I'm doing some experiments and measurements. I send some random TCP packets to a laptop(with fedora system), that laptop reacts by sending ICMP packets of type 3 and code 10, which means Destination ...
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1answer
214 views

Locating and pinging a satellite

I want to ping a satellite, or ping some far off computer and know for sure that somewhere in the traceroute is a satellite hop I know that if I ping a computer in , say, australia (i am in the UK) ...
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0answers
83 views

traceroute shows destination host only

I run tracert to a target in our company network and got the following result (ip and names are mangled) $ tracert target.example.com Tracing route to target.example.com [192.168.10.1] over a ...
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Firewalld Zones and ICMP

How are the zones in firewalld configured w.r.t ICMP packets? and do they act differently for interfaces and sources? [Original Q from serverfault] 1. How firewalld route ICMP packets? I would ...
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How to configure Windows XP/windows 7 to support icmpv6 redirection?

I construct an icmpv6 redirection packet. When I send it to Linux, it works well. Then I modify its destination ip and mac address and send it to the corresponding windows XP/7 system, but windows XP/...