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I'm looking for some best practices or Security guidelines for Firewall and VPN. Trying to study a little more about network security and write a sort of decalogue (set of rules). Usefull to follow when implementing a new system. Any ideas?


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  • Start with a two-way deny-all, then only add allow rules when a) requested, b) documented, c) reviewed by someone else and d) review their validity every quarter/6-months/year/whatever.
  • Syslog and retain every deny for at least a quarter.
  • Try to only allow through standard ports.
  • Ensure all FW actions are authorised and audited.
  • Dependant on volume maybe use Splunk to analyse where your denies are coming from, can be useful but can get expensive.
  • Document everything to within an inch of its life, there's nothing as horrifying to new sysadmins as an undocumented FW.
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+1 to starting with deny all. There're few things harder to debug than a firewall with accept all as the base rule – Paul D'Ambra Sep 23 '11 at 10:18
Thanks for your infos!! Have you any links or documents? like Cisco man or SANS docs? – Possa Sep 23 '11 at 10:20
I don't know about that last point...well, not the point itself, but rather the assertion. – Bart Silverstrim Sep 23 '11 at 11:59

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