Access Control Lists

Question 1

ACL Basics

Answer 1

ACLs can be configured on a router to permit or deny a packet based on a list of conditions

• This list of conditions is read sequentially, top to bottom, by the router until a match is made
• the last condition is always an implied “deny any”
• You can permit or deny packets based upon such things as:
  
  • source address
  • destination address
  • TCP & UDP ports

Question 2

The 3 Ps for using ACLs

Answer 2

One ACL per protocol
One ACL per interface
One ACL per direction

Question 3

standard ACL

Answer 3

standard acls should be applied closest to the destination

Question 4

Extended ACL

Answer 4

extended ACLs should be applied close to the source as possible

• filter IP packets based on several attributes:
• source and destination IP addresses
• source and destination TCP and UDP ports
• protocol type

Question 5

Basic ACL rules

Answer 5

1. never work with an access list that is actively applied

2. new lines are always added to the end of thenumbered access list

Question 6

Access list syntax for Standard ACL

Answer 6

access-list number deny/permit/remark network or protocol or specific source

Network uses a wildcard mask following