CISCO IOS REMOTE ACCESS VPN STEP-BY-STEP CONFIGURATION WITH DETAIL
Introduction
The concept of a Remote Access Virtual Private Network (VPN)
has become more relevant than ever. As businesses continue to grow with a rising
reliance on remote work and global collaboration, the need for secure and
reliable remote network access is paramount. A Remote Access VPN provides a
secure tunnel between a remote user and the corporate office network, ensuring that data will remain encrypted and protected from potential cyber threats. For
businesses seeking to protect their data and give their employees flexibility,
this technology has become essential.
Focusing on the technical implementation of this solution,
one of the most robust and widely used tools is the Cisco router. Known for its
reliability and advanced features.
Understanding Remote Access VPN: What is Remote Access VPN?
A Remote Access Virtual Private Network (VPN) is a
technology that allows remote users to securely establish a connection to a
remote office network over the less secure internet. Unlike traditional
on-premises network access, users can securely access corporate resources
virtually from any geographical location using Remote Access VPN, as long
as they have an internet connection. In contrast with site-to-site VPNs, which
are primarily used to connect entire networks of different branches of the same
organization, allowing them to share resources as if they were in
the same physical location, a Remote Access VPN focuses on individual users and
their internet-connected devices, offering a more private, secure and flexible
approach to network access.
The advantages of Remote Access VPNs are numerous, particularly in the context of today's dynamic work environments:
Enhanced Security Remote Access VPN offers a significant
level of security by encrypting data transmitted over the internet, it protects
sensitive information from hacking and eavesdropping, this is crucial,
especially when employees need to access corporate network resources from
a public place or unsecured Wi-Fi networks.
The Authentication process validates that the data was sent from
the actual sender.
Limit the unauthorized users from accessing the network by
applying Access control.
Confidentiality prevents the data from being read or copied as
the data is being transported.
Data Integrity guarantees that the data has not been
reformed.
Flexibility and Convenience: Remote Access VPN provides the
necessary flexibility for employees to work from anywhere. Whether they are
working from home, a coffee shop, or while traveling. They can easily access
their corporate office resource like files, applications, and systems necessary
to perform their jobs more precisely.
Scalability: As remote access VPNs are readily expandable to support more users as an organization grows,
they are scalable.
Because of its scalability, it's a cost-effective choice for companies of all kinds.
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| Remote Access VPN |
How to set up a Remote Access VPN for the Cisco Router IOS platform?
Configuring an IPsec Remote Access VPN on a Cisco IOS router involves several steps and commands. Here's a breakdown:
Step – 1:
Define the authentication and authorization methods:
aaa authentication login REMOTEUSER local
aaa authorization network REMOTEUSER-AUTH-LIST local
Step – 2:
Configure ISAKMP (Internet Security Association and Key Management Protocol) Policy for phase 1 negotiation:
crypto isakmp policy 10
authentication pre-share
hash md5
Group 2
Step – 3:
ip access-list extended VPN_SPLIT
permit ip any any
Step – 4:
Define the VPN client group profile:
crypto isakmp client configuration group cisco
key cisco123
dns 8.8.8.8
pool VPNPOOL
acl VPN_SPLIT
max-user 5
exit
Step – 5:
Define encryption parameters for phase-2 which will used for actual data encryption and assign it to crypto dynamic map:
crypto dynamic-map map1 10
set transform-set set1
reverse-route
exit
Step – 6:
Create a crypto map and apply AAA lists that were created in Step-1:
crypto map map1 client configuration address respond
crypto map map1 client authentication list REMOTEUSER
crypto map map1 isakmp authorization list REMOTEUSER-AUTH-LIST
crypto map map1 10 ipsec-isakmp dynamic map1
Step – 7:
Apply crypto map to the internet interface (outbound interface):
Interface serial 1/0
crypto map map1
How to verify the isakmp association and ipsec association?
This command will show Isakmp Security Associations:
show crypto isakmp sa
This command will show IPsec Security Associations:
show crypto ipsec sa
debug crypto isakmp
debug crypto ipsec