mailing list archives
Re: SMURF amplifier block list
From: "Alex P. Rudnev" <alex () Relcom EU net>
Date: Sat, 18 Apr 1998 16:23:36 +0400 (MSD)
Why don't use the filter
deny icmp any 0.0.0.255 255.255.255.0 echo-request
on the incoming lines? It just block 99.999% of this smurf amplifiers;
and I hardly think someone eve sence this restriction for the real PING
On Fri, 17 Apr 1998, Dean Anderson wrote:
Date: Fri, 17 Apr 1998 18:09:08 -0400
From: Dean Anderson <dean () av8 com>
To: jlixfeld () idirect ca
Cc: nanog () merit edu
Subject: Re: SMURF amplifier block list
Does no ip directed broadcast really work?
Yes. It works.
And it works for whatever your particular netmask or broadcast address
happens to be, which is what's important.
The only time you shouldn't do it globally is when some other network
really needs to see broadcasts. For example, If we manage a client's
network with HP OpenView over the internet, we need to be able to send them
directed broadcasts, so that OpenView host discovery will work. Patrol
works the same way, as do other products. In this case you can't use the
"no ip directed broadcast" switch, but you can still set up access rules
which do the same thing except for the permitted network.
Bottom line is that you should protect your network from people who would
either abuse it via smurfing, or simply have no business looking for hosts
on your network. You have the tools to do it.
Plain Aviation, Inc dean () av8 com
We Make IT Fly! (617)242-3091 x246
Aleksei Roudnev, Network Operations Center, Relcom, Moscow
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