Cisco Access List Configuration Examples (Standard, Extended ACL) on Routers Etc
| Access List Type | Number Range |
| IP Standard Access Lists | 1-99 |
| IP Standard Access Lists (expanded range ... | 1300-1999 |
| IP Extended Access Lists | 100-199 |
| IP Extended Access Lists (expanded range ... | 2000-2699 |
Full Answer
What is standard access list?
Standard access lists control traffic by comparing the source address of packets to the addresses configured in the access list.
How to differentiate between standard and extended access lists?
You can differentiate between standard and extended access lists in the numbered format simply by looking at the access list number. Based on the number used when access list is created, the router also knows which type of syntax to expect as the list is entered. By using numbers 1 – 99 or 1300 – 1999, you are essentially telling the router that you want to create a standard IP access list. Thus the router will expect the standard IP access list syntax specifying only the source IP address in access list entries.
What command to apply an access list to an interface?
The command to apply an access list to an interface is ip access-group entered in interface configuration mode:
What is the command to create an access list?
The command to create an access list, not surprisingly, is access-list entered in configuration mode. As we just discussed the number we use to identify an access list cannot be any arbitrary number. This number rather must belong to the range of numbers available for the type of access list you want to create. At the moment, we are interested in creating a standard numbered access list. So we can choose a number from the ranges 1-99 or 1300-1999.
Which command is used to define a named access list?
The command used to define a named access list is ip access-list which has several options:
What is the show IP access list command?
Exam Concept – Use the show ip access-list command to verify an access list has been created, while use the show ip interface command to verify that the access list is applied to an interface. Cisco now wants you to thoroughly understand how to use the show commands for troubleshooting on the CCNA
What is standard access control list?
The standard access control list will allow you to either permit or deny traffic from a specific source IP address or IP network.
What is final access list?
A final access lists test is done by actually generating traffic that the access-list is supposed to permit or deny and see the results.
What port is ACL 110?
The ACL 110 will permit traffic that is coming from any address on the 92.128.2.0 network (source network) towards any destination IP on port 80. The ‘any’ statement is there so as to allow traffic towards any IP destination on port 80 .
What is ACL in router?
An Access Control List (ACL) is a list of rules that control and filter traffic based on source and destination IP addresses or Port numbers. This happens by either allowing packets or blocking packets from an interface on a router, switch, firewall etc.
What are the two types of ACLs?
On Cisco devices we have two main types of ACLs. These are Standard Access Control Lists and Extended Access Control Lists.
What is an ACE in a list?
Individual entries or statements in an access lists are called access control entries (ACEs). Each ACE entry defines a traffic flow (source/destination) that will be either allowed or blocked.
Is Cisco ASA Firewall Fundamentals self published?
He is a self-published author of two books ("Cisco ASA Firewall Fundamentals" and "Cisco VPN Configuration Guide") which are available at Amazon and on this website as well.
What is the 10 in Access List?
Now wait a minute, wait a minute, we put in permit 172.16 with that wildcard mask, what's the 10 there? What is that 10 that just sprung to life inside of our access list? The 10 is an automatic sequence number that is added to the access list. It will be 10 by default. If we were to create another entry...so we type in access-list 1 permit 192.168.1.0 0.0.0.255, it would be automatically provided a sequence number. And it would be 20, the next one in the list and the next one will be 30 and 40 and 50, it's how we keep track of them, the sequence number, the order we created them in.
How to remove an access list?
Removing an access list is very easy, remember that powerful no command, type in no access-list and then the number of the access list you want to remove. Be careful, be careful. Let's say you typed in no access-list 1 permit 172.16.0.0 0.0.255.255. So you want to remove a standard access list entry you created earlier. You type in no and you specify the whole command that you typed in before, will that remove just that one entry? I will repeat that, will that remove just the one entry? At first thought, yeah, that's at first thought, but if you try that and you tested it? No, that is not what will happen. It won't remove just that one entry, what will it do? It will get rid of the whole thing, so some of you out there have had exposure to this. It is really bizarre behavior in the IOS.
Why use named access control lists?
What's the benefit of a named access control list? Well named access control list, first of all, allows us to provide a descriptive name. So instead of our access control list being called 79 we can provide a descriptive name and that name can help us understand what the access control list is designed to accomplish. But what we really benefit from by using named access control lists is the ability to edit them, add and delete entries within that ACL.
Can you put in parameters that are not acceptable to the standard IP version 4 access control list?
It won't let you put in parameters that are not acceptable to the standard IP version 4 access control list. So you put in the wrong number, if you put in a 101, where you are trying to create a standard IP version 4 access control list, it will give you the syntax for an extended access control list, right? So be careful with your numbering, pick the right numbers and then you'll specify which you want to happen to this traffic. Do you want to permit it? Do you want to deny it? You can also put a remark, what is a remark? It's just a description. So you can describe this access control list, so when you review the access control list later, you will know what it's for.
Does standard look at destination?
So you see standard does not look at destination, which practically speaking, is not very useful. The lack of being able to look for a destination is quite limiting, you usually want to look for where it's coming from and going to.
Can you edit access control list?
And this is important, remember how we said, if we want to edit the access control list, we might want to add an entry here and there, but we can only do that with named syntax, we are unable to do that here with this standard numbering syntax, but those sequence numbers will be the defining factor of where our entry goes. If we add or move or delete or change and we will see that later on, we will see that later on only when we enter into the named access control list syntax of how these sequence numbers can be used and manipulated to our advantage.
