ASA Firewall Configuration

Before you start

Objectives : You will be able to configure CISCO ASA.
Prerequisites: Before configure ASA you must have knowledge of Firewalls..
Tags : ASA, CISCO, Firewall.

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ASA Firewall Basic

ASA stand for Adaptive Security Appliance. It is a security device which is created by CISCO. It can be placed between two different zone, i.e. inside and outside. If we have different type of server then these server are placed in demilitarized zone.
Now, we will understand the difference between Router configuration and Firewall configuration. CISCO, create almost same configuration mode, but router mainly used for routing and it handle different routing protocol. ASA, itself can run these protocols, but the main work of ASA is to handle issue related to the security.

Configuration of ASA interface

Here, we will discuss, how we can configure CISCO ASA interface. We have different things which are used to configure CISCO ASA. Very First, we will assign particular IP address on an interface, after that we will assign a particular Zone. After the ZONE, we will give a security level to that zone. Grater the Security level means grater is the trust. So, we will give 100 security level for 'inside' zone. By default, security level for 'inside' is '100' and '0' for all other zones.<
First we will go to global configuration mode.

configure terminal

Select interface to configure

Now we will choose a particular interface for configuration.

interface gigabitethernet [port]

interface gigabitethernet 0/0

Configure IP address

Now, we will assign IP address to that interface. If, we will not define subnet mask then, by default it will consider subnet mask as class full mask.

ip address [ip_address] [subnet_mast]

ip address 192.168.1.1 255.255.255.0

Now, Define a particular Zone

Now, we will put this interface, in a particular zone. In most cases, engineer put 'inside', 'outside' zone.
nameif [zone_name]

nameif inside

Define a security level for this interface

After, putting any interface we define a security level. We discussed security level at the top of the post. the command will be look like:
security-level 100

security-level 100

Finally, change the state of the interface.

CISCO, by default put their routers in down state. Like, router, ASA interfaces are down by default, so the last step is to turn on the interface by 'no shutdown' command.
no shutdown

no shutdown

Note:If you have any doubt please post in comment box.