How does a Stateless firewall or any device using just ACLs allow return traffic if no state is being maintained? If I am using a Cisco router that has ACL configured for Internet traffic, how is the traffic from the internet being allowed back in if it doesn't maintain a state table?


  • 1
    It maintains a table, or you use reflexive ACLs, which accomplishes the same thing.
    – Ron Maupin
    Aug 10 '16 at 22:07
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 14 '17 at 23:09

There is need for output and input rules. A stateless firewall filter, also known as an access control list (ACL), does not statefully inspect traffic. Instead, it evaluates packet contents statically and does not keep track of the state of network connections. In contrast, a stateful firewall filter uses connection state information derived from other applications and past communications in the data flow to make dynamic control decisions.

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