Contents
Is reflexive ACL important?
Reflexive access lists are an important part of securing your network against network hackers, and can be included in a firewall defense. Reflexive access lists provide a level of security against spoofing and certain denial-of-service attacks.
What is a reflexive ACL?
The idea of reflexive ACL is to take a packet flow, extract session information i-e source/destination IP and ports and create dynamic entry in access-list that is applied in opposite direction, to permit the “mirrored” flow. We basically need a named access-list to implement traffic reflection.
Is Cisco ACL stateful?
The reflexive access-list is the poor man’s stateful firewall. By default an access-list on a Cisco router doesn’t keep track of any connections. The only thing it cares about is whether an incoming packet matches a certain statement or not.
What is dynamic ACL?
A dynamic ACL is an ACL that is created on and stored in an LDAP, RADIUS, or Active Directory server. A Dynamic ACL action dynamically creates ACLs based on attributes from the AAA server. Because a dynamic ACL is associated with a user directory, this action can assign ACLs specifically per the user session.
What is Cbac Cisco?
The Context-Based Access Control (CBAC) feature of the Cisco IOS® Firewall Feature Set actively inspects the activity behind a firewall. CBAC specifies what traffic needs to be let in and what traffic needs to be let out by using access lists (in the same way that Cisco IOS uses access lists).
What is time based access?
Time-based access-list are type of access-list which allow network access on the basis of time period.It is useful when you want to place restrictions on outbound or inbound traffic on the basis of particular time of the day or particular days of a week.
Are ACL stateful or stateless?
A session ACL is a stateful firewall which keeps track of the state of network connections such as TCP streams and UDP communication that hit the firewall.
Are ACLs routers stateful?
To start with, Firewalls perform Stateful inspection while ACLs are limited to being Stateless only. Stateful is a per-flow packet inspection, whereas Stateless (ACL) is a per-packet packet inspection. Unlike Firewalls, ACLs are features on Routers and Layer 3 devices.
What is standard ACL and extended ACL?
A “Standard” ACL allows you to prioritize traffic by the Source IP address. An “Extended” ACL provides greater control over what traffic is prioritized.
What can a reflexive ACL do for a TCP connection?
In other words, a reflexive ACL can detect when a user initiates a connection to the outside world and can allow only returning traffic for that user’s connection. Unlike extended IP ACLs that can do this somewhat for TCP connections (with the established parameter), RACLs can do this with all IP protocols.
Which is an example of a reflexive ACL?
Here are some of the issues with the ACL configuration in Example 8-2: You probably do not know which DNS server or servers the internal user is using, so you must allow all DNS server replies back into your network. All port numbers greater than 1023 must be allowed because this is what the source device randomly chooses.
What’s the difference between racls and extended IP ACLs?
Unlike extended IP ACLs that can do this somewhat for TCP connections (with the established parameter), RACLs can do this with all IP protocols. Basically, RACLs are a stripped-down version of Cisco’s CBAC stateful firewall feature, which is part of the Cisco IOS Firewall feature set (discussed in Chapter 9).
Can a standard ACL keep track of traffic?
As you recall, standard and extended ACLs do not keep track of the state of a connection; therefore, if someone inside sends traffic to the Internet, it is very hard to safely allow the returning traffic back into your network without opening a large hole on your perimeter router.