Configure Site to Site VPN on Cisco ASA

by SinaOnline Network Training

Welcome to my channel , in this  video i will configure site to site vpn on Cisco ASA . i will show you the steps to set up a secure and reliable VPN connection between two Cisco Adaptive Security Appliances (ASAs).

Before we dive into the technical aspects, let’s take a moment to understand the importance of site-to-site VPNs in today’s interconnected world. As businesses expand globally, secure communication between different locations becomes paramount. Whether you’re connecting remote offices, data centers, or branch networks, a site-to-site VPN offers a robust solution to ensure data confidentiality, integrity, and availability.

Assumptions:

  • You have physical or remote access to the Cisco ASA device.
  • You have administrative access to the ASA via SSH, console cable, or ASDM (Adaptive Security Device Manager).

Step 1: Basic ASA Configuration

  1. Connect to the ASA using SSH or the console cable.
  2. Log in with your administrator credentials.

hostname ASA_NAME enable password YOUR_ENABLE_PASSWORD passwd YOUR_CONSOLE_PASSWORD interface GigabitEthernet0/0 nameif outside security-level 0 ip address YOUR_OUTSIDE_IP 255.255.255.0 no shutdown exit interface GigabitEthernet0/1 nameif inside security-level 100 ip address YOUR_INSIDE_IP 255.255.255.0 no shutdown exit route outside 0.0.0.0 0.0.0.0 YOUR_GATEWAY_IP 1

  1. Replace ASA_NAME, YOUR_ENABLE_PASSWORD, YOUR_CONSOLE_PASSWORD, YOUR_OUTSIDE_IP, YOUR_INSIDE_IP, and YOUR_GATEWAY_IP with your specific values.

Step 2: Define ISAKMP Policy

  1. Configure the ISAKMP (Internet Security Association and Key Management Protocol) policy to specify the encryption and authentication parameters for the VPN.

crypto isakmp policy 10 authentication pre-share encryption aes-256 hash sha group 2 lifetime 86400

Step 3: Create a Pre-shared Key

  1. Define a pre-shared key that will be used to authenticate the remote VPN peer.

crypto isakmp key YOUR_PRESHARED_KEY address REMOTE_PEER_IP

Replace YOUR_PRESHARED_KEY with your chosen pre-shared key and REMOTE_PEER_IP with the IP address of the remote VPN peer.

Step 4: Create a Crypto Map

  1. Create a crypto map that defines the remote peer’s IP, transform sets, and access control list (ACL) for traffic to be encrypted.

crypto map MY_CRYPTO_MAP 10 match address VPN_ACL crypto map MY_CRYPTO_MAP 10 set peer REMOTE_PEER_IP crypto map MY_CRYPTO_MAP 10 set transform-set MY_TRANSFORM_SET

Replace MY_CRYPTO_MAP, VPN_ACL, REMOTE_PEER_IP, and MY_TRANSFORM_SET with your desired values.

Step 5: Create an Access Control List (ACL)

  1. Define an access control list (ACL) that identifies which traffic should be encrypted and sent over the VPN.

access-list VPN_ACL extended permit ip LOCAL_NETWORK SUBNET_MASK any

Replace LOCAL_NETWORK and SUBNET_MASK with your local network’s details.

Step 6: Apply Crypto Map to an Interface

  1. Apply the crypto map to the ASA’s outside interface.

crypto map MY_CRYPTO_MAP interface outside

Step 7: Save the Configuration

  1. Save the configuration changes.

write memory

Step 8: Verify the VPN

  1. Check the VPN status using the following command:

show crypto isakmp sa show crypto ipsec sa

These commands will display information about the IKE and IPsec tunnels.

That’s it! You’ve configured a Site-to-Site VPN on a Cisco ASA. Remember to adjust the configuration to match your specific network topology and security requirements. Additionally, ensure that the remote peer’s configuration matches the parameters you’ve configured here for successful VPN establishment.