On 7 Jun 2005, at 20:11, Frank Duignan wrote:
> I was looking for something similar for the same reason - I had hoped
> limit ssh access to clients from a particular country - apparently NTL
> screws things up for Ireland by using UK assigned IP addresses. Can
> you limit your whitelist to particular address and address ranges used
> by known ISP's?
You can use iptables to allow access based on addresses or ranges. I'm
guessing that enough ranges to cover most Irish ISPs would lead to
quite a few iptables rules. Which brings up a question - how well does
iptables scale? Will you start to notice slowdowns with 100 rules?
1000? 10000? I know that this of course depends on the rules, and on
the CPU. And in fact, I suppose if your rules are on state new, as mine
are for ssh, it hardly matters - a further 1 second delay in setting up
an ssh connection wouldn't be a disaster, generally.
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