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?

dimo414
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    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? – Martijn Heemels Sep 04 '09 at 13:21
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    It's done only for a false sense of security. – Michael Hampton Mar 06 '13 at 10:15
  • [This article](http://www.linuxhowtos.org/Security/disable_ping.htm) 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

7 Answers7

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
dimo414
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KPWINC
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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
Saurabh Barjatiya
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    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 08:40
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.

koenigdmj
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3

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

Sathish
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0

Just do this:

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

William Hilsum
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