.. _vpn-dmvpn: DMVPN ----- **D** ynamic **M** ultipoint **V** irtual **P** rivate **N** etworking DMVPN is a dynamic VPN technology originally developed by Cisco. While their implementation was somewhat proprietary, the underlying technologies are actually standards based. The three technologies are: * **NHRP** - NBMA Next Hop Resolution Protocol RFC2332_ * **mGRE** - Multipoint Generic Routing Encapsulation / mGRE RFC1702_ * **IPSec** - IP Security (too many RFCs to list, but start with RFC4301_) NHRP provides the dynamic tunnel endpoint discovery mechanism (endpoint registration, and endpoint discovery/lookup), mGRE provides the tunnel encapsulation itself, and the IPSec protocols handle the key exchange, and crypto mechanism. In short, DMVPN provides the capability for creating a dynamic-mesh VPN network without having to pre-configure (static) all possible tunnel end-point peers. .. note:: DMVPN only automates the tunnel endpoint discovery and setup. A complete solution also incorporates the use of a routing protocol. BGP is particularly well suited for use with DMVPN. Baseline Configuration: **STEPS:** #. Create tunnel config (`interfaces tunnel`) #. Create nhrp (`protocols nhrp`) #. Create ipsec vpn (optional, but recommended for security) (`vpn ipsec`) The tunnel will be set to mGRE if for encapsulation `gre` is set, and no `remote-ip` is set. If the public ip is provided by DHCP the tunnel `local-ip` can be set to "0.0.0.0". If you do set the `remote-ip` directive at any point, the interface will need to be `delete`'d from the config and recreated without the `remote-ip` config ever being set. .. figure:: ../_static/images/vpn_dmvpn_topology01.png :scale: 40 % :alt: Baseline DMVPN topology Baseline DMVPN topology HUB Configuration ^^^^^^^^^^^^^^^^^ .. code-block:: sh interfaces tunnel { address encapsulation gre local-ip multicast enable description parameters { ip { } } } } protocols { nhrp { tunnel { cisco-authentication holding-time multicast dynamic redirect } } } vpn { ipsec { esp-group { lifetime <30-86400> mode tunnel pfs enable proposal <1-65535> { encryption aes256 hash sha1 } proposal <1-65535> { encryption 3des hash md5 } } ike-group { key-exchange ikev1 lifetime <30-86400> proposal <1-65535> { encryption aes256 hash sha1 } proposal <1-65535> { encryption aes128 hash sha1 } } ipsec-interfaces { interface } profile { authentication { mode pre-shared-secret pre-shared-secret } bind { tunnel } esp-group ike-group } } } HUB Example Configuration: .. code-block:: sh set interfaces ethernet eth0 address '198.51.100.41/30' set interfaces ethernet eth1 address '192.168.1.1/24' set system host-name 'HUB' set interfaces tunnel tun0 address 10.0.0.1/24 set interfaces tunnel tun0 encapsulation gre set interfaces tunnel tun0 local-ip 198.51.100.41 set interfaces tunnel tun0 multicast enable set interfaces tunnel tun0 parameters ip key 1 set protocols nhrp tunnel tun0 cisco-authentication SECRET set protocols nhrp tunnel tun0 holding-time 300 set protocols nhrp tunnel tun0 multicast dynamic set protocols nhrp tunnel tun0 redirect set vpn ipsec ipsec-interfaces interface eth0 set vpn ipsec ike-group IKE-HUB proposal 1 set vpn ipsec ike-group IKE-HUB proposal 1 encryption aes256 set vpn ipsec ike-group IKE-HUB proposal 1 hash sha1 set vpn ipsec ike-group IKE-HUB proposal 2 encryption aes128 set vpn ipsec ike-group IKE-HUB proposal 2 hash sha1 set vpn ipsec ike-group IKE-HUB lifetime 3600 set vpn ipsec esp-group ESP-HUB proposal 1 encryption aes256 set vpn ipsec esp-group ESP-HUB proposal 1 hash sha1 set vpn ipsec esp-group ESP-HUB proposal 2 encryption 3des set vpn ipsec esp-group ESP-HUB proposal 2 hash md5 set vpn ipsec esp-group ESP-HUB lifetime 1800 set vpn ipsec esp-group ESP-HUB pfs dh-group2 set vpn ipsec profile NHRPVPN set vpn ipsec profile NHRPVPN authentication mode pre-shared-secret set vpn ipsec profile NHRPVPN authentication pre-shared-secret SECRET set vpn ipsec profile NHRPVPN bind tunnel tun0 set vpn ipsec profile NHRPVPN esp-group ESP-HUB set vpn ipsec profile NHRPVPN ike-group IKE-HUB set protocols static route 0.0.0.0/0 next-hop 1.1.1.2 set protocols static route 192.168.2.0/24 next-hop 10.0.0.2 set protocols static route 192.168.3.0/24 next-hop 10.0.0.3 HUB on AWS Configuration Specifics ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Setting this up on AWS will require a "Custom Protocol Rule" for protocol number "47" (GRE) Allow Rule in TWO places. Firstly on the VPC Network ACL, and secondly on the security group network ACL attached to the EC2 instance. This has been tested as working for the offical AMI image on the AWS Marketplace. (Locate the correct VPC and security group by navigating through the details pane below your EC2 instance in the AWS console) SPOKE Configuration ^^^^^^^^^^^^^^^^^^^ SPOKE1 Configuration: .. code-block:: sh interfaces tunnel { address encapsulation gre local-ip multicast enable description parameters { ip { } } } } protocols { nhrp { tunnel { cisco-authentication map { nbma-address register } holding-time multicast nhs redirect shortcut } } } vpn { ipsec { esp-group { lifetime <30-86400> mode tunnel pfs enable proposal <1-65535> { encryption aes256 hash sha1 } proposal <1-65535> { encryption 3des hash md5 } } ike-group { key-exchange ikev1 lifetime <30-86400> proposal <1-65535> { encryption aes256 hash sha1 } proposal <1-65535> { encryption aes128 hash sha1 } } ipsec-interfaces { interface } profile { authentication { mode pre-shared-secret pre-shared-secret } bind { tunnel } esp-group ike-group } } } SPOKE1 Example Configuration .. code-block:: sh set interfaces ethernet eth0 address 'dhcp' set interfaces ethernet eth1 address '192.168.2.1/24' set system host-name 'SPOKE1' set interfaces tunnel tun0 address 10.0.0.2/24 set interfaces tunnel tun0 encapsulation gre set interfaces tunnel tun0 local-ip 0.0.0.0 set interfaces tunnel tun0 multicast enable set interfaces tunnel tun0 parameters ip key 1 set protocols nhrp tunnel tun0 cisco-authentication 'SECRET' set protocols nhrp tunnel tun0 map 10.0.0.1/24 nbma-address 198.51.100.41 set protocols nhrp tunnel tun0 map 10.0.0.1/24 'register' set protocols nhrp tunnel tun0 multicast 'nhs' set protocols nhrp tunnel tun0 'redirect' set protocols nhrp tunnel tun0 'shortcut' set vpn ipsec ipsec-interfaces interface eth0 set vpn ipsec ike-group IKE-SPOKE proposal 1 set vpn ipsec ike-group IKE-SPOKE proposal 1 encryption aes256 set vpn ipsec ike-group IKE-SPOKE proposal 1 hash sha1 set vpn ipsec ike-group IKE-SPOKE proposal 2 encryption aes128 set vpn ipsec ike-group IKE-SPOKE proposal 2 hash sha1 set vpn ipsec ike-group IKE-SPOKE lifetime 3600 set vpn ipsec esp-group ESP-SPOKE proposal 1 encryption aes256 set vpn ipsec esp-group ESP-SPOKE proposal 1 hash sha1 set vpn ipsec esp-group ESP-SPOKE proposal 2 encryption 3des set vpn ipsec esp-group ESP-SPOKE proposal 2 hash md5 set vpn ipsec esp-group ESP-SPOKE lifetime 1800 set vpn ipsec esp-group ESP-SPOKE pfs dh-group2 set vpn ipsec profile NHRPVPN set vpn ipsec profile NHRPVPN authentication mode pre-shared-secret set vpn ipsec profile NHRPVPN authentication pre-shared-secret SECRET set vpn ipsec profile NHRPVPN bind tunnel tun0 set vpn ipsec profile NHRPVPN esp-group ESP-SPOKE set vpn ipsec profile NHRPVPN ike-group IKE-SPOKE set protocols static route 192.168.1.0/24 next-hop 10.0.0.1 set protocols static route 192.168.3.0/24 next-hop 10.0.0.3 SPOKE2 Configuration .. code-block:: sh interfaces tunnel { address encapsulation gre local-ip multicast enable description parameters { ip { } } } } protocols { nhrp { tunnel { cisco-authentication map { nbma-address register } holding-time multicast nhs redirect shortcut } } } vpn { ipsec { esp-group { lifetime <30-86400> mode tunnel pfs enable proposal <1-65535> { encryption aes256 hash sha1 } proposal <1-65535> { encryption 3des hash md5 } } ike-group { key-exchange ikev1 lifetime <30-86400> proposal <1-65535> { encryption aes256 hash sha1 } proposal <1-65535> { encryption aes128 hash sha1 } } ipsec-interfaces { interface } profile { authentication { mode pre-shared-secret pre-shared-secret } bind { tunnel } esp-group ike-group } } } SPOKE2 Example Configuration .. code-block:: sh set interfaces ethernet eth0 address 'dhcp' set interfaces ethernet eth1 address '192.168.3.1/24' set system host-name 'SPOKE2' set interfaces tunnel tun0 address 10.0.0.3/24 set interfaces tunnel tun0 encapsulation gre set interfaces tunnel tun0 local-ip 0.0.0.0 set interfaces tunnel tun0 multicast enable set interfaces tunnel tun0 parameters ip key 1 set protocols nhrp tunnel tun0 cisco-authentication SECRET set protocols nhrp tunnel tun0 map 10.0.0.1/24 nbma-address 198.51.100.41 set protocols nhrp tunnel tun0 map 10.0.0.1/24 register set protocols nhrp tunnel tun0 multicast nhs set protocols nhrp tunnel tun0 redirect set protocols nhrp tunnel tun0 shortcut set vpn ipsec ipsec-interfaces interface eth0 set vpn ipsec ike-group IKE-SPOKE proposal 1 set vpn ipsec ike-group IKE-SPOKE proposal 1 encryption aes256 set vpn ipsec ike-group IKE-SPOKE proposal 1 hash sha1 set vpn ipsec ike-group IKE-SPOKE proposal 2 encryption aes128 set vpn ipsec ike-group IKE-SPOKE proposal 2 hash sha1 set vpn ipsec ike-group IKE-SPOKE lifetime 3600 set vpn ipsec esp-group ESP-SPOKE proposal 1 encryption aes256 set vpn ipsec esp-group ESP-SPOKE proposal 1 hash sha1 set vpn ipsec esp-group ESP-SPOKE proposal 2 encryption 3des set vpn ipsec esp-group ESP-SPOKE proposal 2 hash md5 set vpn ipsec esp-group ESP-SPOKE lifetime 1800 set vpn ipsec esp-group ESP-SPOKE pfs dh-group2 set vpn ipsec profile NHRPVPN set vpn ipsec profile NHRPVPN authentication mode pre-shared-secret set vpn ipsec profile NHRPVPN authentication pre-shared-secret SECRET set vpn ipsec profile NHRPVPN bind tunnel tun0 set vpn ipsec profile NHRPVPN esp-group ESP-SPOKE set vpn ipsec profile NHRPVPN ike-group IKE-SPOKE set protocols static route 192.168.1.0/24 next-hop 10.0.0.1 set protocols static route 192.168.2.0/24 next-hop 10.0.0.2 .. _RFC2332: https://tools.ietf.org/html/rfc2332 .. _RFC1702: https://tools.ietf.org/html/rfc1702 .. _RFC4301: https://tools.ietf.org/html/rfc4301