Route-Based Site-to-Site VPN to Azure (BGP over IKEv2/IPsec)

This guide shows an example of a route-based IKEv2 site-to-site VPN to Azure using VTI and BGP for dynamic routing updates.

For redundant / active-active configurations see Route-Based Redundant Site-to-Site VPN to Azure (BGP over IKEv2/IPsec)

Prerequisites

  • A pair of Azure VNet Gateways deployed in active-passive configuration with BGP enabled.

  • A local network gateway deployed in Azure representing the Vyos device, matching the below Vyos settings except for address space, which only requires the Vyos private IP, in this example 10.10.0.5/32

  • A connection resource deployed in Azure linking the Azure VNet gateway and the local network gateway representing the Vyos device.

Example

WAN Interface

eth0

On-premises address space

10.10.0.0/16

Azure address space

10.0.0.0/16

Vyos public IP

198.51.100.3

Vyos private IP

10.10.0.5

Azure VNet Gateway public IP

203.0.113.2

Azure VNet Gateway BGP IP

10.0.0.4

Pre-shared key

ch00s3-4-s3cur3-psk

Vyos ASN

64499

Azure ASN

65540

Vyos configuration

  • Configure the IKE and ESP settings to match a subset of those supported by Azure:

set vpn ipsec esp-group AZURE lifetime '3600'
set vpn ipsec esp-group AZURE mode 'tunnel'
set vpn ipsec esp-group AZURE pfs 'dh-group2'
set vpn ipsec esp-group AZURE proposal 1 encryption 'aes256'
set vpn ipsec esp-group AZURE proposal 1 hash 'sha1'

set vpn ipsec ike-group AZURE dead-peer-detection action 'restart'
set vpn ipsec ike-group AZURE dead-peer-detection interval '15'
set vpn ipsec ike-group AZURE dead-peer-detection timeout '30'
set vpn ipsec ike-group AZURE ikev2-reauth
set vpn ipsec ike-group AZURE key-exchange 'ikev2'
set vpn ipsec ike-group AZURE lifetime '28800'
set vpn ipsec ike-group AZURE proposal 1 dh-group '2'
set vpn ipsec ike-group AZURE proposal 1 encryption 'aes256'
set vpn ipsec ike-group AZURE proposal 1 hash 'sha1'

  • Enable IPsec on eth0

set vpn ipsec interface 'eth0'

  • Configure a VTI with a dummy IP address

set interfaces vti vti1 address '10.10.1.5/32'
set interfaces vti vti1 description 'Azure Tunnel'

  • Clamp the VTI’s MSS to 1350 to avoid PMTU blackholes.

set interfaces vti vti1 ip adjust-mss 1350

  • Configure the VPN tunnel

set vpn ipsec authentication psk azure id '198.51.100.3'
set vpn ipsec authentication psk azure id '203.0.113.2'
set vpn ipsec authentication psk azure secret 'ch00s3-4-s3cur3-psk'
set vpn ipsec site-to-site peer azure authentication local-id '198.51.100.3'
set vpn ipsec site-to-site peer 203.0.113.2 authentication mode 'pre-shared-secret'
set vpn ipsec site-to-site peer 203.0.113.2 authentication remote-id '203.0.113.2'
set vpn ipsec site-to-site peer 203.0.113.2 connection-type 'respond'
set vpn ipsec site-to-site peer 203.0.113.2 description 'AZURE PRIMARY TUNNEL'
set vpn ipsec site-to-site peer 203.0.113.2 ike-group 'AZURE'
set vpn ipsec site-to-site peer 203.0.113.2 ikev2-reauth 'inherit'
set vpn ipsec site-to-site peer 203.0.113.2 local-address '10.10.0.5'
set vpn ipsec site-to-site peer azure remote-address '203.0.113.2'
set vpn ipsec site-to-site peer 203.0.113.2 vti bind 'vti1'
set vpn ipsec site-to-site peer 203.0.113.2 vti esp-group 'AZURE'

  • Important: Add an interface route to reach Azure’s BGP listener

set protocols static route 10.0.0.4/32 interface vti1

  • Configure your BGP settings

set protocols bgp system-as 64499
set protocols bgp neighbor 10.0.0.4 remote-as '65540'
set protocols bgp neighbor 10.0.0.4 address-family ipv4-unicast soft-reconfiguration 'inbound'
set protocols bgp neighbor 10.0.0.4 timers holdtime '30'
set protocols bgp neighbor 10.0.0.4 timers keepalive '10'

  • Important: Disable connected check 

set protocols bgp neighbor 10.0.0.4 disable-connected-check