12

I feel like this should be a really simple thing to do, but googling and checking SF I didn't see anything. I'm trying to make my Fedora server not respond to pings, how do I do that?

4
  • This article explains how to do this.
    – Sam Cogan
    Jul 28 '09 at 21:58
  • Additionally, you can use "Blackhole" security: the server simply won't answer connection attemps to closed ports, so portscan becomes a difficult one ;)
    – kolypto
    Jul 28 '09 at 22:46
  • 10
    I've never understood the advantages of disabling ICMP Echo Requests on servers. It makes monitoring and debugging network connectivity troublesome. Servers will usually have one or more low ports open for service anyway, so it's not like you can blackhole them. Could you let me know your reason, please? Sep 4 '09 at 13:21
  • 2
    It's done only for a false sense of security. Mar 6 '13 at 10:15
25

To disable the PING response, add the following line to your init script for the network:

echo 1 >/proc/sys/net/ipv4/icmp_echo_ignore_all

To reenable the PING response do this:

echo 0 >/proc/sys/net/ipv4/icmp_echo_ignore_all

Update:

To make the change permanent add the following line to /etc/sysctl.conf:

net.ipv4.icmp_echo_ignore_all=1
1
  • how can i do it for windows server family??
    – AminM
    Mar 5 '14 at 15:21
12

It is better to use firewall for these purposes, so that you can optionally enable ping from some systems, esp monitoring systems

iptables -t filter -I INPUT -p icmp --icmp-type echo-request -s monitoring_system -j ACCEPT
iptables -t filter -I INPUT -p icmp --icmp-type echo-request -j DROP
2
  • 5
    +1 For selective enabling Jul 29 '09 at 23:30
  • 3
    Just in case it's not obvious to iptables newbies, replace "monitoring_system" with the IP/range of the server(s) which should be able to ping the server. All other ping requests will be silenty dropped.
    – Coops
    Jul 30 '09 at 8:40
11

Add the following line to /etc/sysctl.conf:

net.ipv4.icmp_echo_ignore_all=1

It has the same effect as the above echo lines.

2

You can also use this command to disable ping request

sysctl net.ipv4.icmp_echo_ignore_all=1

To enable it again

sysctl net.ipv4.icmp_echo_ignore_all=0

Finally save it sysctl -p

2
  • 1
    Weird, the opposite works on my system with Ubuntu 14.04. I am pinging localhost if it matters. Jul 1 '15 at 3:04
  • 1
    Sorry! I recheked now and corrected. Tried in CentOS 7.
    – Sathish
    Jul 2 '15 at 16:57
0

Just do this:

echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
0

open your /etc/sysctl.conf and append this line

net.ipv4.icmp_echo_ignore_all = 1

and execute this command

sysctl -p

it's still usable after reboot

-1

Firewall block ICMP connections.

especially icmp echo.

1
  • 7
    However, do not block all ICMP traffic because this will e.g. break Path MTU discovery.
    – knweiss
    Jul 28 '09 at 22:08

Not the answer you're looking for? Browse other questions tagged or ask your own question.