Skip to main content
Share Your Experience: Take the 2024 Developer Survey

Questions tagged [icmp]

ICMP is the Internet Control Message Protocol. It is used for diagnostic purposes, for querying information, and for transmitting network-level error messages. ICMPv6, the version for IPv6, is also used for configuring nodes on the link.

Filter by
Sorted by
Tagged with
0 votes
0 answers
24 views

Server not responding to ICMP requests

I have 4 servers running on rocky linux at a datacenter in Chicago but one is not answering to ping requests. I have been checking for solutions for day but so far things look good, what I am missing? ...
swissrockie's user avatar
1 vote
1 answer
188 views

Host will not send ICMP "fragmentation needed" if received packet length is greater than its MTU?

I'm in the middle of figuring out an MTU related issue in a network. Lacking some knowledge, hoping to get some clarification here :) I have a setup, where a client host (with MTU=1500 bytes ...
eeyou's user avatar
  • 13
0 votes
1 answer
100 views

What's the differnce between "Connection timed out" v/s "No route to host" for ncat command?

I tried to use ncat command to 2 diff unknown IPs from a CENTOS 7 (linux) terminal. [abc@localhost ~]$ ncat -zv 10.11.78.5 22 Ncat: Version 7.50 ( https://nmap.org/ncat ) Ncat: No route to host. [abc@...
Ayush Raj's user avatar
  • 101
2 votes
1 answer
210 views

How to disable Ping response (ICMP) in Linux then bring back up?

I'm trying to test the aliveness of some of my services by continuously pinging them to make sure they're up. It checks if 'alive' by pinging the address (192.168.20.1). I've tried disabling it via ...
Andrew Narvaez's user avatar
0 votes
0 answers
29 views

Can the source IP of an ICMP reply message be altered with rules like iptables?

I have set up ip_forward=1 and rp_filter=2 on CentOS 7, which has two network interfaces: eth0 192.168.89.100/24 eth1 192.168.66.200/24 I hope that after eth1 receives an ICMP request, it will ...
EthylL2's user avatar
0 votes
0 answers
95 views

Linux kernel does not accept an ICMPv6 router advertisement but sends redirect to same address instead

I'm using dhcpcd to receive ICMPv6 router advertisements from my ISP on ppp0 and everything works after a fresh boot. However, some time later, upon a disconnect and ppp0 reconnection, this does not ...
MikeP's user avatar
  • 1
0 votes
1 answer
136 views

Changing source address of ICMP packets from 1 interface to another

In my box, I have two ethernet interfaces. Due to the constraints of the system I am dealing with, I need all ICMP response messages to have the source address of 1 of the interfaces. An example: A ...
WakkaTrout's user avatar
0 votes
1 answer
94 views

Traceroute from VM guest does not go past Host PC to internet

I have created an Ubuntu virtual machine on my PC, and I was trying out the traceroute command, as I need it for a college project. However, when I ran "traceroute www.google.com", what I ...
Boni Daniel's user avatar
0 votes
0 answers
105 views

ping program not response the icmp error message

My operation like this: ping -s 8950 10.10.1.100 . I can capture the icmp error message(frag needed and DF set, mtu=8900) with tcpdump from the interface, but the ping program not frag packets ...
Richina's user avatar
0 votes
0 answers
139 views

Route a Virtual IP without NAT to a non-virtual IP

How can I route data with a Linux server (Ubuntu) from a VIP to another IP address. I'm currently using keepalived, but it uses a NAT and I don't want that. However, it should be checked via icmp ...
newby567's user avatar
2 votes
1 answer
1k views

How do we access the "icmp" protocol in ip6tables?

The ip6tables command accepts icmp and icmpv6 protocols: $ sudo ip6tables -A INPUT -p icmp -j ACCEPT $ sudo ip6tables -A INPUT -p ipv6-icmp -j ACCEPT However, when I test with the ping6 command: $ ...
Alexis Wilke's user avatar
  • 2,909
0 votes
1 answer
125 views

Filtering the ICMP packets on Solaris using IP-addresses from the table

I'm currently working with Packet Filter on Solaris machine, trying to create a rule that would filter out all ICMP packets of particular type and code. Here is my rule line: block out quick proto ...
zlatonick's user avatar
  • 149
1 vote
1 answer
790 views

Kubuntu 21.10: All ports (open or closed) return ICMP admin-prohibited, even with no firewall enabled. How to fix?

Running an up-to-date installation of Kubuntu 21.10. If I run any network service on the machine, I'm unable to reach it from anywhere else on my network. The error is always "Host unreachable&...
fdmillion's user avatar
  • 2,898
0 votes
0 answers
454 views

ping Minimum Interval?

No, not the 0.2s available to unprivileged users. What is the minimum interval that ping (from iputils s20190709) supports? I asked it to : ping -s 18 -W 2 -w 300 -qOni 0.000024 ... but it seems to ...
robut's user avatar
  • 433
1 vote
1 answer
851 views

Nmap is not sending ICMP timestamp requests when -PP flag is set

I'd like nmap to send ICMP timestamp requests to the host. To achieve this I use the command: nmap -PP "ip addr" But among requests generated by nmap there are no ICMP requests, only TCP ...
Maxim's user avatar
  • 13
0 votes
0 answers
215 views

ICMP replies captured but not considered by ping

There is a host with a tunnel interface tunint1 with an assigned IP address. When I'm trying to ping via this interface I cannot see any replies but there are ICMP packets (both requests and replies), ...
resaix's user avatar
  • 1
0 votes
0 answers
156 views

Why ping don't response for long time even -W is specified?

I'm just confused with ping. As per my understanding, when I ping some IP address, it sends an ICMP message to the destination, and if there is no response, it get either "request timeout" ...
Vespene Gas's user avatar
0 votes
1 answer
356 views

Linux ignores ECHO REQUESTs that come from one interface but are within the IP range of the other

I ping the WiFi IP of the Linux notebook from the router and it responds fine. I ping the WIFI address from a PC which is visible both directly from the LAN (eth1) and via the router from the WiFi ...
ndemou's user avatar
  • 2,819
0 votes
0 answers
49 views

Workflow for compiling and installing a single existing kernel module?

I am working on creating a patch in the Linux kernel. All of my work occurs in the file net/ipv4/icmp.c (and associated header.) So far, every time I want to test my code, I run make -j $(getconf ...
YOLT's user avatar
  • 1
13 votes
4 answers
2k views

Is there any utility for performing ICMP testing ("ping") in only one direction?

I've been having trouble with some network configuration lately which has been tricky to resolve. It seems this would be much easier to diagnose if I knew which direction the traffic was failing to ...
Philip Couling's user avatar
1 vote
1 answer
332 views

Allow/Deny ICMP "on demand" from normal user (Sysctl, Sudo, /proc)

I would like to set up an account on a CentOS 7.8 that can allow/deny ping (icmp echo) "on demand". This works great logged as root, example : echo 0 > /proc/sys/net/ipv4/...
Greuh's user avatar
  • 13
0 votes
1 answer
155 views

Respond and send ICMP only to certain user's mac address

I need to block ICMP requests for all user's except the groupt that is supposed to manage the VM. Since we access the VM via VPN we have a different IP every time we send a ping to the VM, can I only ...
Rafael Moreira's user avatar
9 votes
1 answer
23k views

What is the filter expression to only sniff ICMP packets?

What is the filter expression to only sniff ICMP packets given the source IP address is 18.23.54.78 and the destination IP address is 12.67.24.89? The filter order must start with the protocol name ...
data_science_dal's user avatar
0 votes
0 answers
132 views

Will Linux kernel verifies if source MAC and IP are match in ICMP request?

I have following configuration of the systems: When I issued ping 192.168.1.200 form Switch, I found the ICMP request packet's source IP in IP header is 1.1.1.2 but the source MAC in L2 header is ...
sharpblade's user avatar
0 votes
1 answer
97 views

Strange ICMP packet

I have an Ubuntu server with iptables that only allows echo request and reply for ICMP and log and drop other ICMP traffic. There is an always on SSH connection between this server and another Ubuntu ...
Ken's user avatar
  • 1
2 votes
2 answers
14k views

Server does not respond to ping - ICMP is received and nothing happens

I have a server with 2 interfaces connected with dhcp to two different subnets. These 2 different subnets are connected to the same switch into 2 different interfaces. # ip a 1: lo: <LOOPBACK,UP,...
hudac's user avatar
  • 779
0 votes
0 answers
2k views

iptables: how to block traceroute and allow ping?

Hi first sorry for my english. I'm trying to block traceroute --icmp (tracert) while still permitting the ping, using iptables. The problem is that when I permit the traffic of echo request, to allow ...
ZaKeR GFX's user avatar
0 votes
0 answers
60 views

Pinging default gateway on a Linux virtual machine

I have two question about the network. I started to ping my router from my Linux virtual machine and I have intercepted these ICMP frames. I noticed that the destination MAC address is not my router ...
Bartosz Sochacki's user avatar
1 vote
1 answer
819 views

View packet data of ping

Is there a flag or other utility (perhaps tcpdump?) that can be used to see the outgoing packets that are sent via the ping utility? For example: $ ping -c 5 google.com PING google.com (172.217.14.78)...
David542's user avatar
  • 339
1 vote
1 answer
16k views

How to allow icmp for your machine? [closed]

I want to allow icmp (ping) for my server. I was reading about IPTables and read that to allow a ping to your machine, you need to have INPUT rule as well as a FORWARD rule. Because INPUT only handles ...
csharpnewbie's user avatar
1 vote
3 answers
310 views

Tcp connection packets ignoring network delays, ping shows delays [closed]

I've introduced a 2000ms latency to all network packets using openwrt netem module. # This is run on the terminal of the OpenWRT router tc qdisc add dev wlan1 root netem delay 2000ms I can clearly ...
TheMeaningfulEngineer's user avatar
3 votes
1 answer
305 views

Host unreacheable from laptop but reacheable from desktop

I have a Synology NAS at home (let's call it ananas), it is attached to my router via ethernet. I also have a desktop (let's call it Aero), it is connected to the same router via wifi. I configured in ...
Soulthym's user avatar
  • 177
0 votes
0 answers
32 views

Iptables rules enabled for allowing icmp/ping for only specific IP address with RHEL7 OS not working [duplicate]

The server where iptables rules are enabled is RHEL 6.4. From this server, I tried to allow icmp echo request from only one specific IP address (host with RHEL7.5 OS). I used the following rules: ...
sungtm's user avatar
  • 124
32 votes
12 answers
85k views

How can I ping multiple IP addresses at the same time?

I'm aware of the methods where you can run a Bash for loop and ping multiple servers, is there a Linux CLI tool that I can use which will allow for me to do this without having to resort to writing a ...
slm's user avatar
  • 371k
2 votes
1 answer
1k views

TAP/TUN capturing ICMP packets

I'm trying to capture raw ethernet packets into a user space program. Having read about the TAP/TUN capabilities of the kernel, I went on and created the following setup: Two systems connected ...
Eitan Michaelson's user avatar
1 vote
0 answers
343 views

How to view ICMP Redirect Logs

I have read on multiple sources that there is are logs for rejected ICMP redirect messages, one of them being "Understanding Linux Network Internals: Guided Tour to Networking on Linux" By Christian ...
TorqueNoFriction's user avatar
1 vote
2 answers
359 views

Should I remove ICMP Protocol from firewall rules base on security concern?

As you can see from the screenshot of GCP firewall rule page, should I remove ICMP Protocol from firewall rules base on security concern? Will it lower the chance of being attacked? I'm using CentOS ...
Leo's user avatar
  • 13
9 votes
1 answer
2k views

How come one can successfully ping 127.0.0.2 on Linux?

On a FreeBSD system with a loopback network interface … % ifconfig lo0 lo0 link up loopback drv_running running multicast nd6 performnud auto_linklocal no_radr link rxcsum ...
JdeBP's user avatar
  • 69.2k
2 votes
1 answer
6k views

It is possible to traceroute without touching ICMP?

I often run into a situation where I want to traceroute an IP without root or NET_RAW cap in Linux. I have attempted to send a UDP packet with a small TTL but no ttl error is emitted at all. It seems ...
Dummmy's user avatar
  • 213
1 vote
1 answer
2k views

How to Disable Ping ( TCP ) in Linux all the time? [closed]

I want to disable ping response all the time. I use the following command for disable ICMP ping iptables -A INPUT -p icmp --icmp-type echo-request -j DROP what should I do for disable TCP ping ?
Víctor Marcianes's user avatar
0 votes
1 answer
113 views

Exclude interface when send ICMP ping

for build small linux application I need to check the internet connectivity of the system. But my box have multiple network interfaces with interfaced for backup internet connection. I need to do some ...
sameera's user avatar
  • 304
1 vote
1 answer
1k views

How to check whether kernel received MLD query or not?

On the Internet I found this command netstat -p icmp6 -s which can dump how many MLD queries received by the kernel. But I have Busybox for my system and because of this I'm unable to run netstat ...
vivek's user avatar
  • 131
0 votes
0 answers
304 views

mtu 9000 issues only on tcp and not icmp possible?

I have a connection between two datacenters and rsync between them stalls often. I think it is related to the mtu 9000 (I actualy set it to 8900 because of some possible vlan use) I have the ...
f1 outsourcing's user avatar
44 votes
4 answers
14k views

What Linux process is responsible for responding to pings?

I have a Linux based process controller that occasionally locks up to the point where you can't ping it (i.e. I can ping it, then it becomes no longer pingable without any modifications to network ...
Izzo's user avatar
  • 971
0 votes
1 answer
184 views

I have disabled all rules in firewall, but still can tracert from LAN

I have disabled all positive rules in firewall on my pfSense box, and I can't browse Web, but I still can tracert 10.10.0.251 from LAN machine and receive 3 hops from my ISP (behind the router). ...
Dims's user avatar
  • 3,255
6 votes
5 answers
8k views

tcpdump -i any doesn't work on FreeBSD

How to listen all interfaces on FreeBSD with tcpdump > tcpdump -i any tcpdump: any: No such device exists (BIOCSETIF failed: Device not configured) (I would like to listen ICMP)
Dims's user avatar
  • 3,255
2 votes
1 answer
8k views

UDP port unreachable although process is listening

I am experimenting with communication over UDP port 6666 (the goal is setting up a listener for netconsole, but that's not really relevant here). On the listening side, nc -luv 6666. On the sending ...
berndbausch's user avatar
  • 3,557
20 votes
3 answers
56k views

How to Disable Ping Response (ICMP echo) in Linux all the time?

I want to disable ping response all the time on my Ubuntu operating system, the following commands work but only until the system reboots: Ping off: echo "1" > /proc/sys/net/ipv4/...
HardRebootHackerHD's user avatar
1 vote
0 answers
503 views

Reading MLDv2 queries using an IPv6 socket

I have mrd6 installed on my raspberry pi. It registers with a local interface (tun0) and periodically transmits MLDv2 queries over it. According to [RFC3810], MLDv2 message types are a subset of ...
S.P's user avatar
  • 111
4 votes
0 answers
4k views

No buffer space available - ICMP

I'm trying to set up a Heartbeat client on a linux machine (CentOS Linux release 7.3.1611) which is sending ICMP echo requests to roughly 1300 hosts. However, in future this number will be higher. The ...
P.Ackland's user avatar