Copyright © 2001-2005 Thomas M. Eastep
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2007/07/19
This article applies to Shorewall 3.0 and later. If you are running a version of Shorewall earlier than Shorewall 3.0.0 then please see the documentation for that release.
Enabling “ping” will also enable ICMP-based traceroute. For UDP-based traceroute, see the port information page.
In Shorewall , ICMP echo-request's are treated just like any other connection request.
In order to accept ping requests from zone z1 to zone z2 where the
policy for z1 to z2 is not ACCEPT, you need a rule in
/etc/shorewall/rules of the form:
#ACTION SOURCE DEST PROTO DEST PORT(S) Ping/ACCEPT z1 z2
Example 1. Ping from local zone to firewall
To permit ping from the local zone to the firewall:
#ACTION SOURCE DEST PROTO DEST PORT(S) Ping/ACCEPT loc $FW
If you would like to accept “ping” by default even when
the relevant policy is DROP or REJECT, copy
/usr/share/shorewall/action.Drop or
/usr/share shorewall/action.Reject respectively to
/etc/shorewall and simply add this
line to the copy:
Ping/ACCEPT
With that rule in place, if you want to ignore “ping” from z1 to z2 then you need a rule of the form:
#ACTION SOURCE DEST PROTO DEST PORT(S) Ping/DROP z1 z2
Example 2. Silently drop pings from the Internet
To drop ping from the internet, you would need this rule in
/etc/shorewall/rules:
#ACTION SOURCE DEST PROTO DEST PORT(S) Ping/DROP net $FW
Note that the above rule may be used without changing the action files to prevent your log from being flooded by messages generated from remote pinging.