ICMP Echo-request (Ping)
Tom
Eastep
2005-08-31
2001-2005
Thomas M. Eastep
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version
1.2 or any later version published by the Free Software Foundation; with
no Invariant Sections, with no Front-Cover, and with no Back-Cover
Texts. A copy of the license is included in the section entitled
GNU Free Documentation
License
.
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.
'Ping' Management
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
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
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.
Revision History
1.3
2005-08-31
CR
Updated for Shorewall 3
1.2
2004-01-03
TE
Add traceroute reference
1.1
2003-08-23
TE
Initial version converted to Docbook XML