Flex VPN Website to Website Configuration

June 30, 2022

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Digital non-public networks (VPNs) are mode to supply low value and safe communications between websites whereas bettering productiveness with extending company networks to distant customers. (Distant entry VPNs). Main community supplier Cisco helps a wide range of VPN varieties and most of them require completely different configurations, present instructions, and debugging instructions. Every VPN sort additionally helps completely different options. FlexVPN answer is launched by Cisco to simplify VPN deployments and covers all VPN varieties equivalent to Website to website VPN, Hub and spoke VPN (together with spoke to spoke visitors) and distant entry.

At present we glance extra intimately about Flex VPN, study its structure, options, benefits, fast information and many others.

What’s Flex VPN?

Flex VPN is a framework to configure IPSec VPNs on Cisco units it was created for simplification of deployment of VPN options of all varieties of VPNs besides GETVPN. FlexVPN is predicated on IKEv2 and never supported on IKEv1. It integrates completely different configuration parameters into one type therefore additionally termed as unified Overlay VPN. Since it’s primarily based on IKEV2 which has some myriad advantages over IKEv1 a few of them are listed right here:

Useless peer detection and community handle translation traversal – Web Key alternate model 2 (IKEV2) supplies in-built help for lifeless peer detection (DPD) and community handle translation traversal (NAT-T).
Certificates URLs – certificates could be referenced by way of a URL and hash as an alternative of being despatched inside IKEv2 packets to keep away from fragmentation.
Denial of service assault resilience (Anti-DOS) – IKEv2 doesn’t course of a request till it identifies the requester, which addresses to some extent the denial-of-service points as have been in IKEv1 which could be spoofed to carry out in depth cryptographic processing (costly in nature) from false areas.
EAP help – IKEv2 permits use of extensible Authentication protocol (EAP) help for authentication
A number of crypto engines – one engine can deal with IPV4 visitors and one other engine can deal with IPV6 visitors or one engine can deal with each IPV4 and IPV6 visitors.
Reliability and state administration (Windowing) – makes use of sequence numbers and acknowledgments to supply dependable and error free processing and logistics and shared state administration.
IKEv2 Suite-B help – are set of cryptographic algorithms promulgated by nationwide safety company as a part of cryptographic modernization program. Suite-B for web key alternate and IPSec is outlined underneath RFC-4869. The elements of Suite-B are as underneath:
- Superior encryption normal (AES) – 128- and 256-bit keys are configured in IKEv2. For information visitors AES needs to be utilized in Galois counter mode (GCM) configured in IPSec remodel set.
- Elliptic curve digital signature algorithm (ECDSA) – configured in IKEv2 profile.
- Safe hashing algorithm 2 (SHA-256 and SHA-384) configured in IKEv2 proposal and IPSec remodel set.

Options of Flex VPN

It helps interpretability
It help dynamic routing
It helps IPSec routing
Failover mechanism is straightforward and in addition source-based failover is supported
Gives full AAA administration

Configuration elements – Flex VPN

The next IKEv2 /IPSec configuration elements are required for Flex VPN

Parts	Description of elements
IKEv2 proposal	●It’s obligatory ●Defines encryption, integrity algorithm, DH group used for defense in negotiation of IKEv2 SA ●Can specify a couple of entry for every possibility ●Don’t comprise authentication methodology and SA lifetime in proposal
IKEv2 coverage	●It’s obligatory ●Match friends and associates the IKEv2 proposal by binding the beforehand create IKEv2 proposal to choose throughout negotiation with the outlined VPN peer
IKEv2 Keyring	●Mandate provided that utilizing PSK authentication ●Used to outline pre-shared keys
IKEv2 Profile	●It’s obligatory ●Outline native/distant IKEv2 identities ●Outline native/distant authentication sort ●Outline IKEv2 keyring whereas utilizing PSK or PKI Trustpoint (if utilizing certificates authentication)
IPSec Rework Set	●Acceptable safety protocols and algorithms for IPSec SA
IPSec Profile	●References the IPSec Rework Set if NOT default ●References the IKEv2 Profile if NOT default ●IPSec Profile hooked up to the Tunnel interface

Sensible defaults – Flex VPN

The Flex VPN configuration could be minimized utilizing sensible defaults of IKEv2 which give default values for all elements excluding IKEv2 profile and Keyring (In case PSK is used). Sensible defaults could be modified primarily based on want, and can solely be displayed within the running-config if utilizing command ‘Present running-config all’ , could be disabled by utilizing ‘no’ earlier than command. All defaults could be deactivated, modified or restored.

Description	Present command	Default values
remodel set	Present crypto ipsec remodel -set default	crypto ipsec transform-set default esp-aes 128 esp-sha-hmac
IPSec Profile	present crypto ipsec profile default	crypto ipsec profile default set transform-set default set ikev2-profile default
IKEv2 Proposal	present crypto ikev2 proposal default	crypto ikev2 proposal default encryption aes-cbc-256 aes-cbc-192 aes-cbc-128 integrity sha512 sha384 sha256 sha1 md5 group 5 2
IKEv2 Coverage	present crypto ikev2 coverage default	crypto ikev2 coverage default match fvrf any proposal default
IKEv2 Authorization Coverage	present crypto ikev2 authorization coverage default	crypto ikev2 authorization coverage default route set interface route settle for any