What is Access Control List

In computer networking, Access Control List or the ACL is the list of the permissions that are attached to an object.  It also refers to the list of the rules that are applied to an object. ACL is designed for two types one for the Gate Access and other for the Audit Access. ACL tells the operating system that what access rights each user has to a particular object.  The ACL has the information of the users and their rights.  Each object has in the ACL has its security attributes. 

The common types of the privileges that a user has are the read, write, execute and the modification permission of an object that can be a file or a folder.  It is a security model in which when a user want to perform a particular action on an object, the operating systems checks whether the user has the permission to access or modify that object. Each ACL has the ACE (Access Control Entries), which includes the users and the group of the users.

The latest security mechanism of the ACL is also known as the role-based Access Control List in which permissions are assigned to the roles and the roles are assigned to the users or the group of the users. ACL is also a network traffic controlling mechanism in which the access to the network resources is only allowed to the authorized users only.

To implement the security in your computer network you may permit or deny a user or the group of the users to access the network resources.

How To Create ACL on Cisco Router

The access lists are usually created by the systems administrators and the network administrators.  In computer network, ACL can be applied on the source IP address, destination IP address, protocol, port number and the data packets type.   On the Cisco Router, you can create the ACL with the following commands.

Steps

• On the Cisco Router, enter the Global Configuration mode.
• Create an ACL no. 1 to permit the traffic from the 192.168.1.1.
• Create ACL no. 2 to block the traffic from this particular IP address 196.145.15.15

R1>enable
R1#configure terminal
R1 (config) #access-list 1 permit 192.168.1.1 (Permit traffic from this IP address)
R1 (config) #access-list 2 deny 196.145.15.15 (Deny traffic from this IP address)
R1 (config) #access-list 2 permit any (use this command to permit the traffic from any IP address).
Based on the above examples you can set your own criteria and permit or deny any particular IP addresses to access the network.

How To Create ACL in Windows Based Operating Systems

• On the Windows Server 2003, double click My Computer > Open up any NTFS drive (C, D, E, and F).
• Right click any file or folder and click Security.
• On the Security tab click Add and check “Allow” to access this file or folder.  Through the Add button you can add any users or group of users and you can set the permission level i.e. write, read, modify, execute, full control or special permissions.
• Similarly you can check the Deny to deny the permissions for that particular file or folder and through Add button you can add any number of users or groups whom you want to restrict to access this file, folder or object.