VPP as IKEv2 responder and strongSwan as initiator

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    |                      |initiator |
|responder+----------------------+strongSwan|
+---------+                      +----------+
                     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=@roadwarrior.vpn.example.com
 leftsubnet=192.168.5.0/24

 # remote: (vpp gateway)
 rightid=@vpp.home
 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 vpp.home
ikev2 profile set pr1 id remote fqdn roadwarrior.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

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:

$ sudo docker exec sswan ipsec up initiator

...
CHILD_SA initiator{1} established with SPIs c320c95f_i 213932c2_o and TS 192.168.5.0/24 === 192.168.3.0/24
connection 'initiator' established successfully

vpp# show ikev2 sa details

iip 192.168.10.1 ispi 7849021d9f655f1b rip 192.168.10.2 rspi 5a9ca7469a035205
 encr:aes-gcm-16 prf:hmac-sha2-256  dh-group:modp-2048
 nonce i:692ce8fd8f1c1934f63bfa2b167c4de2cff25640dffe938cdfe01a5d7f6820e6
       r:3ed84a14ea8526063e5aa762312be225d33e866d7152b9ce23e50f0ededca9e3
 SK_d    9a9b896ed6c35c78134fcd6e966c04868b6ecacf6d5088b4b2aee8b05d30fdda
 SK_e  i:00000000: 1b1619788d8c812ca5916c07e635bda860f15293099f3bf43e8d88e52074b006
         00000020: 72c8e3e3
       r:00000000: 89165ceb2cef6a6b3319f437386292d9ef2e96d8bdb21eeb0cb0d3b92733de03
         00000020: bbc29c50
 SK_p  i:fe35fca30985ee75e7c8bc0d7bc04db7a0e1655e997c0f5974c31458826b6fef
       r:0dd318662a96a25fcdf4998d8c6e4180c67c03586cf91dab26ed43aeda250272
 identifier (i) id-type fqdn data roadwarrior.vpn.example.com
 identifier (r) id-type fqdn data vpp.home
   child sa 0:encr:aes-gcm-16  esn:yes
    spi(i) c320c95f spi(r) 213932c2
    SK_e  i:2a6c9eae9dbed202c0ae6ccc001621aba5bb0b01623d4de4d14fd27bd5185435
          r:15e2913d39f809040ca40a02efd27da298b6de05f67bd8f10210da5e6ae606fb
    traffic selectors (i):0 type 7 protocol_id 0 addr 192.168.5.0 - 192.168.5.255 port 0 - 65535
    traffic selectors (r):0 type 7 protocol_id 0 addr 192.168.3.0 - 192.168.3.255 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=1.02 ms
64 bytes from 192.168.5.2: icmp_seq=2 ttl=63 time=0.599 ms