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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Multiple ICMP destination unreachable messages

I'm load testing some web services hosted on IIS7. The web services make network calls to underlying services in response to client requests. The client requests are simple HTTP requests but the ...
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2answers
292 views

Linux not sending ICMP with iptables `--reject-with`

Using iptables I am trying to reject packets (I want to return an ICMP message). iptables -A FORWARD [...] -j REJECT --reject-with icmp-port-unreach The packets are dropped but using tcpdump I can ...
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1answer
856 views

Forwarding traffic from TUN device (C++ backend) to the default gateway

The following problem is just a piece of the bigger solution I have a problem with. All other elements seem working so far, so I'll try to describe very small piece which I have problem with. I've ...
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1answer
100 views

A non-recoverable error occurred during a database lookup

Short version: Why does Test-Connection report "A non-recoverable error occurred during a database lookup" for an offline host on a different subnet? I'm using PowerShell to ping a remote host with ...
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1answer
65 views

Cannot ping through one of the network interfaces

Setup ubuntu linux VM ( virtual-box) is configured with two interfaces, eth0 and eth1. eth0 is on a bridged network and directly connected to external network. eth1 is on "nat network", which is ...
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1answer
96 views

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 ...
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1answer
157 views

Change the order that an IPTABLE CHAIN is read (Using Fail2Ban)

I have some experience using iptables and fail2ban. Both are working as they should, but I would like to optimize the way packets are "DROPed" when IP & port probing occur. Fail2Ban is doing a ...
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1answer
1k views

Linux PCs sending “ICMP udp port unreachable” to DNS server

So digging around in my syslog I have been noticing a lot of ICMP packets being flagged by our ASAs: %ASA-4-313005: No matching connection for ICMP error message: icmp src Internet:x.x.21.122 dst ...
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1answer
156 views

How can I proxy ICMP requests?

I have a ubuntu server that receives many ping requests from various other servers in the network. I would like to be able to proxy these requests. Using iptable rules I can see how to DROP or ACCEPT ...
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1answer
402 views

Ubuntu stops responding to ping from random clients

I got a ubuntu server running redmine from apache. My clients, can access redmine, but stops responding random, and other clients, can browse redmine fine, when the client with the problem cant ...
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1answer
188 views

What is causing ping sweep?

I am spotting ping sweeps on our firewall log originating from our Windows 2003 SP2 x64 server. The traffic shows sequential pings sent to private ranges only. Eg: 192.168.1.1 192.168.1.2 192.168.1.3 ...
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151 views

No transmission via IP

I'm using netstat on Win XP to check protocol transmission details for TCP, IP, and ICMP. There is transmission only in TCP. No transmission in ICMP is understandable since it's for errors and I ...
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1answer
114 views

Default gateway and ARP confusion

I have the following configuration (I'd post a pic but not enough rep for more than 2): PC1 (10.0.2.10/24) and PC2 (10.0.2.137/29) are connected to a hub, which is connected to a router on interface ...
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0answers
36 views

TCP Handshake fails when ICMP Redirects are enabled

So it seems that due to ICMP redirects it's not possible to connect to a server behind a VPN connection. It immediately responds with a TCP RST (with manifests itself in SSH as ...
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0answers
69 views

What should happen when receiving an ICMP Fragmentation Needed message?

In general, and in particular on a Solaris 10 machine ... See, we are having an issue in our network. I handle some reverse proxy instances on a Solaris 10 server that is behind a load balancer, and ...
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60 views

How can I test an ICMP Re-direct message?

I want to test whether my linux machine is actually accepting ICMP re-direct message and updating the entry in routing table.This is what i have done so far to achieve the same. Simulated a ICMP ...
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85 views

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 ...
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42 views

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 ...
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51 views

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 ...
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481 views

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 ...
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0answers
267 views

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, ...
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145 views

Disable response from outside interface on ASA 5505 while allowing ping (and response from outside) on the inside interface?

On the ASA 5505 How do I allow icmp requests out (and responses back in) while not allowing a response from the outside interface when pinged.
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972 views

Why is my CentOS box rejecting some (but not all) ICMP ping requests from the same remote host?

CentOS 4.x I've got several old CentOS 4.x systems and have configured iptables to allow ICMP traffic. Originally, I had an iptables rule that looked like: -A RH-Firewall-1-INPUT -p icmp --icmp-...
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666 views

Where is HP Procurve route type “ICMP” coming from?

I've got the following test network: Architecture: edge_a: 192.168.e.1 [edge vlan] (edge switch, no acl) [admin vlan] 192.168.m.1/24 core: 192.168.m.2/24 [admin vlan] (core router, yes acl) [...
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18 views

Ping to server disappear for a long time, but reappear after reverse ping to my static IP

Almost every day about 9.00 - 10.00 link to my server goes down. I have two links: direct static IP & Hamachi VPN, usually I lose only the direct link, but Hamachi still works. Most interesting ...
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24 views

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 ...
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12 views

Sonicwall TZ205 can't ping a static IP address from VPN

I have set up a TP-Link WiFi router to a static IP address of 192.168.3.2 on my local LAN (192.168.3.x), with no DHCP. Addresses are provided fine by the Sonicwall. From the local LAN, I can ping 192....
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17 views

How to use icmptx?

in trusty (ubuntu 14.04, both sides) i want to create an icmp tunnel. i don't know how to set ip's. i searched and read some documents like [this]: http://thomer.com/icmptx and [this]: http://null-...
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65 views

Cannot connect to WebDAV when ICMP (ping) is disabled on a server

I have linux as a Webdav server and Windows 10 as a webdav client. I could successfully connect to the webdav server from Windows using: net use * https://mywebdavserver.com/webdav /USER:user pass ...
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79 views

ICMP packets in firewalld zones

How are the zones in firewalld configured w.r.t ICMP packets? and do they act differently for interfaces and sources? 1. How firewalld route ICMP packets? I would assume the main zones act as they ...
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478 views

Timestamp response behaviors in different tools

I was testing out icmp time stamp response on one of my servers using ping and hping3. Here is result of hping3 # hping3 --icmp-ts x.x.x.x HPING x.x.x.x: icmp mode set, 28 headers + 0 data bytes ...
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266 views

ARP/ICMP in a network environment with overlapping IP address

Currently I have lab network setup to mimic customer's network deployment. (According to the customer, they are using VRF over VLAN so that their customer can have overlapping network connecting to ...
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823 views

Wierd traceroute / ICMP issues on Juniper SRX 210BE

I recently acquired Juniper SRX 210BE; until now I've been using Cisco ASA 5505 but I really want to switch over to Juniper world (big FreeBSD fan and all that). I've got FTTC (fiber to the cabnet) ...
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173 views

What is causing this seemingly excessive ICMP traffic?

This seems to occur when I initiate a connection to an IP that I haven't previously before. Is this a botnet trying to say hi to his friends? As you can see I have an ip filter set in this image, ...
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331 views

ICMP ping one way only?

I have 2 W7 hosts (may be others, I haven't checked yet) that are on the network, and can ping the domain controller. They can also ping each other. Yet when I'm on the server, the ping request ...