VPP as IKEv2 initiator and strongSwan as responder

Prerequisites

To make the examples easier to configure docker it is required to pull strongSwan docker image. The networking is done using Linux’ veth interfaces and namespaces.

Setup

First a topology:

192.168.3.2                      192.168.5.2
     +                           loopback
     |                                 +
+----+----+ 192.168.10.2         +-----+----+
|  VPP    |                      |strongSwan|
|initiator+----------------------+responder |
+---------+                      +----------+
                     192.168.10.1

Create veth interfaces and namespaces and configure them:

sudo ip link add gw type veth peer name swanif
sudo ip link set dev gw up

sudo ip netns add ns
sudo ip link add veth_priv type veth peer name priv
sudo ip link set dev priv up
sudo ip link set dev veth_priv up netns ns

sudo ip netns exec ns \
  bash -c "
    ip link set dev lo up
    ip addr add 192.168.3.2/24 dev veth_priv
    ip route add 192.168.5.0/24 via 192.168.3.1"

Create directory with strongswan configs that will be mounted to the docker container

mkdir /tmp/sswan

Create the ipsec.conf file in the /tmp/sswan directory with following content:

config setup
  strictcrlpolicy=no

conn initiator
  mobike=no
  auto=add
  type=tunnel
  keyexchange=ikev2
  ike=aes256gcm16-prfsha256-modp2048!
  esp=aes256gcm16-esn!

# local:
  leftauth=psk
  leftid=@sswan.vpn.example.com
  leftsubnet=192.168.5.0/24

# remote: (gateway)
  rightid=@roadwarrior.vpp
  right=192.168.10.2
  rightauth=psk
  rightsubnet=192.168.3.0/24

/tmp/sswan/ipsec.secrets

: PSK 'Vpp123'

/tmp/sswan/strongswan.conf

charon {
  load_modular = yes
  plugins {
    include strongswan.d/charon/*.conf
  }
  filelog {
    /tmp/charon.log {
      time_format = %b %e %T
      ike_name = yes
      append = no
      default = 2
      flush_line = yes
    }
  }
}
include strongswan.d/*.conf

Start docker container with strongSwan:

docker run --name sswan -d --privileged --rm --net=none \
 -v /tmp/sswan:/conf -v /tmp/sswan:/etc/ipsec.d philplckthun/strongswan

Finish configuration of initiator’s private network:

pid=$(docker inspect --format "{{.State.Pid}}" sswan)
sudo ip link set netns $pid dev swanif

sudo nsenter -t $pid -n ip addr add 192.168.10.1/24 dev swanif
sudo nsenter -t $pid -n ip link set dev swanif up

sudo nsenter -t $pid -n ip addr add 192.168.5.2/32 dev lo
sudo nsenter -t $pid -n ip link set dev lo up

Start VPP …

sudo /usr/bin/vpp unix { \
      cli-listen /tmp/vpp.sock \
      gid $(id -g) } \
      api-segment { prefix vpp } \
      plugins { plugin dpdk_plugin.so { disable } }

… and configure it:

create host-interface name gw
set interface ip addr host-gw 192.168.10.2/24
set interface state host-gw up

create host-interface name priv
set interface ip addr host-priv 192.168.3.1/24
set interface state host-priv up

ikev2 profile add pr1
ikev2 profile set pr1 auth shared-key-mic string Vpp123
ikev2 profile set pr1 id local fqdn roadwarrior.vpp
ikev2 profile set pr1 id remote fqdn sswan.vpn.example.com

ikev2 profile set pr1 traffic-selector local ip-range 192.168.3.0 - 192.168.3.255 port-range 0 - 65535 protocol 0
ikev2 profile set pr1 traffic-selector remote ip-range 192.168.5.0 - 192.168.5.255 port-range 0 - 65535 protocol 0

ikev2 profile set pr1 responder host-gw 192.168.10.1
ikev2 profile set pr1 ike-crypto-alg aes-gcm-16 256 ike-dh modp-2048
ikev2 profile set pr1 esp-crypto-alg aes-gcm-16 256

create ipip tunnel src 192.168.10.2 dst 192.168.10.1
ikev2 profile set pr1 tunnel ipip0
ip route add 192.168.5.0/24 via 192.168.10.1 ipip0
set interface unnumbered ipip0 use host-gw

Initiate the IKEv2 connection:

vpp# ikev2 initiate sa-init pr1

vpp# show ikev2 sa details
 iip 192.168.10.2 ispi f717b0cbd17e27c3 rip 192.168.10.1 rspi e9b7af7fc9b13361
 encr:aes-gcm-16 prf:hmac-sha2-256  dh-group:modp-2048
 nonce i:eb0354613b268c6372061bbdaab13deca37c8a625b1f65c073d25df2ecfe672e
       r:70e1248ac09943047064f6a2135fa2a424778ba03038ab9c4c2af8aba179ed84
 SK_d    96bd4feb59be2edf1930a12a3a5d22e30195ee9f56ea203c5fb6cba5dd2bb80f
 SK_e  i:00000000: 5b75b9d808c8467fd00a0923c06efee2a4eb1d033c57532e05f9316ed9c56fe9
         00000020: c4db9114
       r:00000000: 95121b63372d20b83558dc3e209b9affef042816cf071c86a53543677b40c15b
         00000020: f169ab67
 SK_p  i:fb40d1114c347ddc3228ba004d4759d58f9c1ae6f1746833f908d39444ef92b1
       r:aa049828240cb242e1d5aa625cd5914dc8f8e980a74de8e06883623d19384902
 identifier (i) id-type fqdn data roadwarrior.vpp
 identifier (r) id-type fqdn data sswan.vpn.example.com
   child sa 0:encr:aes-gcm-16  esn:yes
    spi(i) 9dffd57a spi(r) c4e0ef53
    SK_e  i:290c681694f130b33d511335dd257e78721635b7e8aa87930dd77bb1d6dd3f42
          r:0a09fa18cf1cf65c6324df02b46dcc998b84e5397cf911b63e0c096053946c2e
    traffic selectors (i):0 type 7 protocol_id 0 addr 192.168.3.0 - 192.168.3.255 port 0 - 65535
    traffic selectors (r):0 type 7 protocol_id 0 addr 192.168.5.0 - 192.168.5.255 port 0 - 65535

Now we can generate some traffic between responder’s and initiator’s private networks and see it works.

$ sudo ip netns exec ns ping 192.168.5.2
PING 192.168.5.2 (192.168.5.2) 56(84) bytes of data.
64 bytes from 192.168.5.2: icmp_seq=1 ttl=63 time=0.450 ms
64 bytes from 192.168.5.2: icmp_seq=2 ttl=63 time=0.630 ms