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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Manually sent ICMP redirect packets [closed]

I'm trying to sent a ICMP redirect to my router to add a new route, as I can not configure it from the portal, and have no access to it though telnet/ssh. The scenario is the next. LAN network ...
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2answers
45 views

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 ...
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1answer
39 views

Why are ICMP packets not captured on the target interface?

I have a network setup as in the picture: The central box is a gateway (Ubuntu 15.10) which relays the packets betwen the various networks (only one is shown on the picture - lan0) and Internet. ...
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1answer
50 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 ...
2
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0answers
32 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
60 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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1answer
92 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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1answer
17 views

Reliable UK/EU ICMP Targets for Periodic Routing/Connectivity Tests?

I need to test routing between my United States datacenters and United Kingdom and Mainland Europe ISPs. This is used to distinguish between general transcontinental routing issues and specific ...
1
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0answers
40 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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0answers
63 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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0answers
48 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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2answers
94 views

Any protocol used by TRACEROUTE ? ICMP or UDP [closed]

Any protocol used by TRACEROUTE : ICMP or UDP or IP ? Or use them all : Encapsulation ?
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1answer
147 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 ...
0
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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
96 views

ICMP - How to send a timestamp and netmask request?

How can I submit a ICMP request for timestamp and netmask request to a host without using NMAP? Is it possible to generate a terminal / command line request with a tool like hping3 or any native ...
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0answers
74 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 ...
1
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1answer
94 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 ...
1
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1answer
193 views

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 ...
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1answer
139 views

ICMP replies - ingress or egress interface (e.g. from a traceroute)

When a traceroute is initiated and receives an ICMP reply from the nodes, which interface should the be replying be from according to RFC 1812. they are actually replying from ingress (where they ...
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2answers
212 views

Why woud ping fail but not traceroute

For a few days now I started making the interesting observation of a machine intermittently not responding to an ICMP ping, while it still responds to an ICMP based traceroute (specifically set via ...
2
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0answers
68 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 ...
2
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1answer
66 views

Outgoing packet has NATed src address

Configuration/Topology: There are 3 machines hadoop2 | hadoop | driver eth0 10.10.15.3 | eth0 10.10.15.2 | tap0 192.168.0.199 ...
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441 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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3answers
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Why can i not ping my host behind the firewall. Cisco asa 5505 [closed]

Can anyone please help me to figure out what in my configuration of the Cisco asa 5505 is wrong or missing. I have multiple host behind my firewall these hosts run different websites on port 80. I am ...
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258 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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2answers
3k views

Block ICMP timestamp & timestamp reply with firewalld

OS: CentOS 7.0 Per the results of a security scan, it has been suggested that we block ICMP timestamp & timestamp reply messages using the firewall (CVE-1999-0524). I've used firewalld to set up ...
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1answer
45 views

IPv4 ICMP Codes/Errors for WAN transmissions

Can someone tell me which IPv4 ICMP Codes/Errors i have to unlock as Best Practise for WAN transmission (RedHat und Cisco)?
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2answers
1k views

Fastest way to scan all hosts that are online

I am looking to find all the hosts that are online in a set of networks. I would like to find all hosts that are online in the entire network of 170.10.. (there are ~64K possible hosts). The network ...
2
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2answers
2k views

Linux is sending ARP requests to hosts in other subnets?

Setup Host B <--> Router <--> Host A Host A: IP = 192.168.1.10, Net = 192.168.1.0/24, VLAN = 1, Default GW = 192.168.1.1 (Router) Host B: IP = 192.168.2.10, Net = 192.168.2.0/24, VLAN ...
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2answers
1k views

Test for ICMP/TCP timestamp responses and disable responses

We had a penetration test done on our servers and one of the vulnerabilities they suggested we fix is that the host responded to an ICMP timestamp request with TCP timestamp. I've looked around but ...
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0answers
790 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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2answers
1k views

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?
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5answers
2k views

iptables, ICMP and RELATED

I am using the following simple iptables rule that accepts related packets: -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT I am letting ICMP echo-requests pass with this other rule: ...
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0answers
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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170 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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1answer
166 views

Is there a dedicated server that is legal to ping frequently with a massive number of devices? [closed]

I have thousands of devices and all of them need to have some kind of communication pass through them every couple of seconds to stay active. Pinging is sufficient for keeping the devices active. Are ...
2
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2answers
759 views

with fully permissive iptables, tcpdump shows icmp echo requests arriving, but no reply's are sent

I'm a bit stumped on where to look next. When using SoftEther IPsec VPN into my network, I can access every server in the main subnet but one. When behind the main firewall, the server responds to all ...
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2answers
61 views

How to manage PING replies? [closed]

How can I manage, for example, my Ubuntu mashine so it doesn't (or does) respond to PING(ICMP ECHO_REQUEST - type 8) requests? Normally almost all computers in a LAN network responds to ping with an ...
1
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1answer
247 views

Did you see similar icmp ever? [closed]

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 ...
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0answers
465 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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1answer
86 views

Iptables REJECT doesn't let the ftp server list files

I had to comment these 2 lines in my iptables file, because for some reason it was denying ftp listing (it does connect to the ftp server, but it never lists the files and then it just times out): -A ...
2
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3answers
230 views

What is the “right way” to monitor network?

My production servers are kept at US east coast and some of the supporting apps are kept at Amsterdam in Europe. There is a Nagios instance running at US east coast as well which does a few port ...
1
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1answer
253 views

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 ...
0
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1answer
151 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
2k views

ICMP echo-reply packets with a much lower TTL (-190) than ICMP time-exceeded packets

When I ping the last three hops of a traceroute path to facebook.com from my location, the ICMP echo-reply packets I get back all have a TTL of respectively 58, 57 and 56. The hops in question are the ...
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2answers
200 views

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 ...
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3answers
4k views

Test a server using MTR through TCP

Is it possible to use MTR over TCP? If not is there an alternative? I have done some research and I am not finding any way to do such a thing, so I'm wondering if anyone has had any experience with ...
4
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2answers
1k views

Packets only get forwarded when tcpdump running on bridge

I ran into the oddest thing when trying to debug a networking issue with OpenStack. I was doing a ping test between virtual machines. The ICMP request packets only made it to the destination host if I ...
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265 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, ...
3
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3answers
2k views

Reasons to turn off/on unreachables messages?

I see on this question (How can I stop Linux from sending ICMP "Destination Unreachable" responses?) that there was a lot of discussion pointing to the fact that you shouldn't turn off ICMP ...