Date: Tue, 4 Jan 2005 13:34:15 +0000 From: Daniel Bye <freebsd-questions@slightlystrange.org> To: FreeBSD-Questions Questions <freebsd-questions@freebsd.org> Subject: Re: my lame attempt at a shell script... Message-ID: <20050104133415.GB57348@catflap.slightlystrange.org> In-Reply-To: <3D1AE682-5DDF-11D9-B56F-000D9333E43C@secure-computing.net> References: <15416223037.20050103193803@hexren.net> <6074EB8D-5DC6-11D9-89A5-000D93AD26C8@tntluoma.com> <F0BE3E23-5DC8-11D9-B56F-000D9333E43C@secure-computing.net> <41D9BA53.4060105@locolomo.org> <2DF07A46-5DD2-11D9-89A5-000D93AD26C8@tntluoma.com> <D7D0CFB3-5DD5-11D9-B56F-000D9333E43C@secure-computing.net> <3E8DD18E8557227C2A3C8E5A@utd49554.utdallas.edu> <AB283AB4-5DD9-11D9-B56F-000D9333E43C@secure-computing.net> <7C6BEBEDE2DB4AC7E55D6843@utd49554.utdallas.edu> <3D1AE682-5DDF-11D9-B56F-000D9333E43C@secure-computing.net>
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On Mon, Jan 03, 2005 at 05:28:56PM -0600, Eric F Crist wrote:
> A couple more questions, then I'm done. Promise.
>=20
> I need to verify whether or not there is an entry for grog_firewall_oif=
=20
> and grog_firewall_iif in /etc/rc.conf. If not, I want to exit with an=20
> error.
Read /etc/rc.conf into your script's namespace using the syntax already
discussed in this thread (`. /etc/defaults/rc.conf'), and you can then
test for the existence of any variable it defines (or doesn't define):=20
if [ -n "${grog_firewall_iif}" ]
then
# Do stuff if ${grog_firewall_iif} is set
else
# Do stuff if ${grog_firewall_iif} is NOT set
fi
Or, to reverse the logic, use [ -z "{grog_firewall_iif}" ]
if [ -z "${grog_firewall_iif}" ]
then
# Do stuff if ${grog_firewall_iif} is NOT set
else
# Do stuff if ${grog_firewall_iif} is set
fi
> Also, a little more advanced, I need to pull information from an=20
> ifconfig output. I need to pull network numbers for both the internal=20
> interface, as well as external interface. For example,
>=20
> vr0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> inet 192.168.1.5 netmask 0xffffff00 broadcast 192.168.1.255
> inet6 fe80::20e:a6ff:feb9:2d3d%vr0 prefixlen 64 scopeid 0x3
> ether 00:0e:a6:b9:2d:3d
> media: Ethernet autoselect (100baseTX <full-duplex>)
> status: active
>=20
> I don't actually need my own address, I need to be able to figure out=20
> that the system, based on the above output, is on the 192.168.1.0/24=20
> network. This will be input into my firewall rulesets.
>=20
> I imagine that there's a util or command around that can do this, or I=20
> can code out the math, but there's got to be an easier way.
ipfw(8) can understand the netmask in hex format, so you can simply say:
ii_nw=3D$(ifconfig "${grog_firewall_iif}" | awk '/inet/ {print $2":"$4}')
${ii_nw} will now contain something like "192.168.37.23:0xffffff00",
which you can safely pass to ipfw(8):
(2)[root@ip73:~]
---># ipfw add 900 allow ip from any to 192.168.37.23:0xffffff00
00900 allow ip from any to 192.168.0.0/24
HTH
Dan
--=20
Daniel Bye
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