Skip site navigation (1)Skip section navigation (2)
Date:      Tue, 07 Aug 2001 10:50:37 -0500
From:      "Douglas G. Allen" <dallen@roe35.lth2.k12.il.us>
To:        "Max Clements" <max.clements@swistgroup.com>
Cc:        freebsd-security@freebsd.org
Subject:   RE: ipfw question
Message-ID:  <200108071050370603.00D90CE5@mail.roe35.lth2.k12.il.us>
In-Reply-To: <DEC925D2FB9081448C3D6EC26E85868C5B66@steinmail.swistgroup.com>
References:  <DEC925D2FB9081448C3D6EC26E85868C5B66@steinmail.swistgroup.com>

next in thread | previous in thread | raw e-mail | index | archive | help
Max,

>Nope - it is the netmask that you associate with one host...
>ifconfig is quite corrent in NOT rejecting it as it is right to use it=
 with
>an alias...

My understanding, based upon a lot of reading and some discussions on=
 Sunday in stable, was that only the first IP address was given the true=
 network mask.  The aliases had to be given the 255.255.255.255 netmask in=
 order for it to work.  Otherwise arp might complain, as it did with two=
 cards active on the machine.

>Nope an alias that is on the same IP segment as the main interface must=
 have
>a netmask of all ones, i.e., 255.255.255.255 or of you like that in hex
>0xffffffff.  Please refer to the FreeBSD /etc/defaults/rc.conf file and=
 see:
>--
>#ifconfig_lo0_alias0=3D"inet 127.0.0.254 netmask 0xffffffff" # Sample=
 alias
>entry.
>--

Ok, that backs up my interpretation above.  Now, how do I get ipfw to allow=
 me to write rules that will filter on both rules and leave both the true=
 address and the alias active and able to see the network?

I've tried firewalling just the true address, firewalling both addresses=
 with the true netmask, firewalling the true address with the actual mask=
 and the alias with 255.255.255.255.  In each case, I could get the true=
 address see the network and the ipfw rules worked as expected.  However=
 the alias didn't function in each case.  Any suggestions?

						Doug


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-security" in the body of the message




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200108071050370603.00D90CE5>