Cisco Crypto ACLs – Do They Really Need to Match?

When starting out with IPsec tunnels it seems to be a common misconception that the crypto ACL, sometimes referred to as the encryption domain or the interesting traffic, must match 100% or be mirrored at both peers or the tunnel won’t come up. This isn’t strictly true. Whilst the ISAKMP phase 1 and IPsec phase 2 proposals must match, the crypto ACL can be different. Assume that at the local

Auditing Cisco ASA Firewall Rules

Today I was auditing a firewall rule set on a Cisco ASA firewall. The firewall has around 399 ACLs (Access Control Lists) comprising of 7272 ACEs (Access Control Entries). Quite a task! Unfortunately I didn’t have any tools to hand such as Cisco Security Manager or something like FirePac to audit the rules and give me some suggestions. Stage 1 was to visually look at the ACLs and spot the obvious

Editing Cisco IOS ACLs

If you’ve administered Cisco PIX or ASA security appliances, you’ll know how easy editing ACLs is. If you want to insert a new rule in to an existing ACL you can easily insert it where you want. For example:

  This will insert the rule at position 12 of the outside_access_in ACL, pushing the existing rule at position 12 down to position 13 and re-ordering everything. In Cisco IOS