R. DuFresne wrote:
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Rob,
Of course you are correct, I should have waited till I had time after
work to offer assistance here. But the backend advise of using one of
the online IP calculators would be a good starting point for finding
the correctparams to pass to iptable.
Thanks for the correction.
Ron DuFresne
On Mon, 1 Aug 2005, /dev/rob0 wrote:
R. DuFresne wrote:
I'm trying to use iptables to block a range of source IP addresses,
but I can't figure out how to specify ranges- i'm trying to block
everything from 172.150-250.*.* on port 8676- can someone help me
out with the rule for this?
For part of the address space 172.128.0.0 - 172.191.255.255 you can
block on 172.128.0.0/10. To get the full range, you might use one
of the online IP calculators to figger in the who shebang.
Unfortunately 172.128.0.0/10 includes some which is not of the space
the OP listed. 172.128.0.0/9 could be used; that is 172.128.0.0
through 172.255.255.255. The rule could be preceded by some -j RETURN
rules with some creative use of user-defined chains.
iptables -N No8676
iptables -A No8676 -s 172.128.0.0/12 -j RETURN
iptables -A No8676 -s 172.144.0.0/14 -j RETURN
iptables -A No8676 -s 172.148.0.0/15 -j RETURN
iptables -A No8676 -s 172.251.0.0/16 -j RETURN
iptables -A No8676 -s 172.252.0.0/14 -j RETURN
iptables -A No8676 -s 172.128.0.0/9 -j DROP
Then, you jump to No8676 for -p $PROTO --dport 8676 from INPUT and/or
FORWARD as may be required for what is wanted.
As an alternative he could list each netblock positively:
iptables -A No8676 -s 172.150.0.0/15 -j DROP
iptables -A No8676 -s 172.152.0.0/13 -j DROP
iptables -A No8676 -s 172.160.0.0/11 -j DROP
iptables -A No8676 -s 172.192.0.0/11 -j DROP
iptables -A No8676 -s 172.224.0.0/12 -j DROP
iptables -A No8676 -s 172.240.0.0/13 -j DROP
iptables -A No8676 -s 172.248.0.0/15 -j DROP
iptables -A No8676 -s 172.250.0.0/16 -j DROP
That requires more rules.
General understanding of TCP/IP and CIDR notation is useful in a case
like this. I would refer the OP to one of the online calculators to
which Ron referred: http://www.cotse.com/networkcalculator.html .
Useful hint to those who might be planning out a network: keep your
hosts in CIDR-addressable netblocks. It's much more convenient for
purposes of firewalling and routing.
- -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
admin & senior security consultant: sysinfo.com
http://sysinfo.com
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Well, thanks to both of you for the information- I think i'm getting the
hang of it... :)
However i'm still completely confused on the whole 0/9 issue- what does
this specify?
I should be able to work it out using that information, but i'd like to
understand it completely for future knowledge :-)
