vyos@vyos:~$ show configuration commands
set interfaces ethernet eth0 address '10.0.0.1/30'
set interfaces vti vti1 address '10.10.10.1/30'
set vpn ipsec authentication psk TEST id '10.0.0.2'
set vpn ipsec authentication psk TEST id '10.0.0.1'
set vpn ipsec authentication psk TEST secret 'test'
set vpn ipsec esp-group TEST-ESP pfs 'disable'
set vpn ipsec esp-group TEST-ESP proposal 1 encryption 'aes256'
set vpn ipsec esp-group TEST-ESP proposal 1 hash 'sha1'
set vpn ipsec ike-group TEST-IKE close-action 'start'
set vpn ipsec ike-group TEST-IKE dead-peer-detection action 'restart'
set vpn ipsec ike-group TEST-IKE dead-peer-detection interval '30'
set vpn ipsec ike-group TEST-IKE key-exchange 'ikev2'
set vpn ipsec ike-group TEST-IKE proposal 1 dh-group '19'
set vpn ipsec ike-group TEST-IKE proposal 1 encryption 'aes256'
set vpn ipsec ike-group TEST-IKE proposal 1 hash 'sha512'
set vpn ipsec interface 'eth0'
set vpn ipsec options disable-route-autoinstall
set vpn ipsec site-to-site peer TEST authentication local-id '10.0.0.1'
set vpn ipsec site-to-site peer TEST authentication mode 'pre-shared-secret'
set vpn ipsec site-to-site peer TEST authentication remote-id '10.0.0.2'
set vpn ipsec site-to-site peer TEST connection-type 'initiate'
set vpn ipsec site-to-site peer TEST default-esp-group 'TEST-ESP'
set vpn ipsec site-to-site peer TEST ike-group 'TEST-IKE'
set vpn ipsec site-to-site peer TEST local-address '10.0.0.1'
set vpn ipsec site-to-site peer TEST remote-address '10.0.0.2'
set vpn ipsec site-to-site peer TEST vti bind 'vti1'

set interfaces ethernet eth0 address '10.0.0.2/30'
set interfaces vti vti1 address '10.10.10.2/30'
set vpn ipsec authentication psk TEST id '10.0.0.1'
set vpn ipsec authentication psk TEST id '10.0.0.2'
set vpn ipsec authentication psk TEST secret 'test'
set vpn ipsec esp-group TEST-ESP pfs 'disable'
set vpn ipsec esp-group TEST-ESP proposal 1 encryption 'aes256'
set vpn ipsec esp-group TEST-ESP proposal 1 hash 'sha1'
set vpn ipsec ike-group TEST-IKE close-action 'trap'
set vpn ipsec ike-group TEST-IKE dead-peer-detection action 'trap'
set vpn ipsec ike-group TEST-IKE dead-peer-detection interval '30'
set vpn ipsec ike-group TEST-IKE key-exchange 'ikev2'
set vpn ipsec ike-group TEST-IKE proposal 1 dh-group '19'
set vpn ipsec ike-group TEST-IKE proposal 1 encryption 'aes256'
set vpn ipsec ike-group TEST-IKE proposal 1 hash 'sha512'
set vpn ipsec interface 'eth0'
set vpn ipsec options disable-route-autoinstall
set vpn ipsec site-to-site peer TEST authentication local-id '10.0.0.2'
set vpn ipsec site-to-site peer TEST authentication mode 'pre-shared-secret'
set vpn ipsec site-to-site peer TEST authentication remote-id '10.0.0.1'
set vpn ipsec site-to-site peer TEST connection-type 'respond'
set vpn ipsec site-to-site peer TEST default-esp-group 'TEST-ESP'
set vpn ipsec site-to-site peer TEST ike-group 'TEST-IKE'
set vpn ipsec site-to-site peer TEST local-address '10.0.0.2'
set vpn ipsec site-to-site peer TEST remote-address '10.0.0.1'
set vpn ipsec site-to-site peer TEST vti bind 'vti1'

PING 10.10.10.2 (10.10.10.2) 56(84) bytes of data.
64 bytes from 10.10.10.2: icmp_seq=1 ttl=64 time=0.091 ms
64 bytes from 10.10.10.2: icmp_seq=2 ttl=64 time=0.083 ms

set interfaces vti vti1 disable
commit

vyos@vyos:~$ show interfaces
Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface    IP Address     MAC                VRF        MTU  S/L    Description
-----------  -------------  -----------------  -------  -----  -----  -------------
eth0         10.0.0.1/30    0c:91:af:95:00:00  default   1500  u/u
eth1         -              0c:91:af:95:00:01  default   1500  u/D
eth2         -              0c:91:af:95:00:02  default   1500  u/D
eth3         -              0c:91:af:95:00:03  default   1500  u/D
eth4         -              0c:91:af:95:00:04  default   1500  u/D
eth5         -              0c:91:af:95:00:05  default   1500  u/D
lo           127.0.0.1/8    00:00:00:00:00:00  default  65536  u/u
             ::1/128
vti1         10.10.10.1/30  n/a                default   1500  u/u
vyos@vyos:~$ show vpn ipsec sa
Connection    State    Uptime    Bytes In/Out    Packets In/Out    Remote address    Remote ID    Proposal
------------  -------  --------  --------------  ----------------  ----------------  -----------  ------------------------
TEST-vti      up       8m4s      504B/504B       6/6               10.0.0.2          10.0.0.2     AES_CBC_256/HMAC_SHA1_96
vyos@vyos:~$ ping 10.10.10.2
PING 10.10.10.2 (10.10.10.2) 56(84) bytes of data.
64 bytes from 10.10.10.2: icmp_seq=1 ttl=64 time=1.94 ms
64 bytes from 10.10.10.2: icmp_seq=2 ttl=64 time=0.759 ms
^C
--- 10.10.10.2 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 0.759/1.350/1.942/0.591 ms