Re: Net Filtering

Dave Andersen (angio@aros.net)
Tue, 08 Oct 1996 00:08:48 -0600

> Date: Tue, 8 Oct 1996 01:08:47 +0000
> Subject: Net Filtering
> Reply-To: "Darren Klein" <dmk@nwdc.com>

>
> Can someone show me what a FILTER for blocking access to the Internet
> would look like? This filter should only allow LAN access.

(RTFM question - it's in the configuration guide).

Assuming your LAN is on 'aaa.bbb.ccc.ddd' and it's a /ZZ netblock (so if you
have a class C sized netblock it'd be a /24) and that you assign dialin
IP addresses in the www.xxx.yyy.zzz netblock (it could be the same
as your LAN netblock), you'd type:

add filter lanonly.in

"Get a filter set up to filter inbound traffic from a modem"

set filter lanonly.in 1 permit www.xxx.yyy.zzz/XX aaa.bbb.ccc.ddd/ZZ

"Allow all traffic from the IPs I assign to the LAN"

set filter lanonly.in 1 deny 0.0.0.0/0 0.0.0.0/0

"Deny everything else"

This filter has the advantage of filtering out IP spoofing of IPs outside
of the dialup netblock.

> Also, how could I then apply this filter to a specific user?

RADIUS. Framed-Filter-Id = "lanonly"

Dave Andersen