List of IP addresses/ subnet ranges to block in firewall

I would like to update the list of IP's/  ranges that are blocked in my firewall.   For example, I currently drop all traffic that come from the ranges below.    

This is not a question about TLD's.  What I'm looking for are candidate IP ADDRESS ranges to block in my firewall- similar to what I've posted below.   I'd rather err on the side of too secure and have to remove entries as needed.  Looking to paint broad strokes here.   We don't do business in CHINA/ RUSSIA- so would be happy to block IP ADDRESS RANGES used by these  countries.   With the increasing incidence of malware/viruses/ hacking and spam-- I'm looking to minimize our exposure as much as possible.   If anyone follows a similar practice, I'd like to know what ranges you block in your perimeter firewall(s).   TIA! mw /26 /26 /26
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In general, the approach to developing firewall policies is not to look for things to block, but to block everything unless access is required.

Of course this can get into difficulties where you want "almost everyone" to have access such as with public websites.  But if your concern is with hacking and spam and viruses, then blocking ranges will probably only provide false peace of mind rather than any real protective measure.

If you are concerned that your perimeter is vulnerable to attack, I'd recommend identifying those vulnerabilities and mitigating them more comprehensively.  For example, incoming spam and viruses are easily mitigated with a service like messagelabs - they will filter your email, and you can then limit any incoming connections to only their servers for SMTP.

For web based attacks, consider using a reverse proxy or an IPS that can inspect the incoming connection prior to them ever reaching your webserver.

Note that "we don't do business in China" doesn't mean that your customers are never in China when they want to interact with you.

If you still want to block IP ranges, then perhaps you could be more specific about what you would consider a candidate?  There are plenty of Geo-IP databases available that you can use to block at a per-country level.
This might help for getting country ranges:

You may as well block RFC address on the outside interface (these are internal address and should never be routed across the internet):     (10.x.x.x)  (172.16.x.x - 172.31.x.x) (192.168.x.x)

Also block the "bogon" list.  These are unallocated or reserved addresses and so you should never see traffic from them:


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mwinickAuthor Commented:
Thank you.
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