When operating VyOS as DMVPN HUB the DMVPN tunnel is always down when issuing the `show vpn ipsec sa` command. The DMVPN configuration is from https://docs.vyos.io/en/latest/vpn/dmvpn.html
```
vyos@vyos:~$ show vpn ipsec sa
Connection State Up Bytes In/Out Remote address Remote ID Proposal
----------------------------- ------- ---------- -------------- ---------------- ----------- ------------------------------------------------
peer-172.18.203.10-tunnel-vti up 52 seconds 252B/252B 172.18.203.10 N/A AES_CBC_256/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
dmvpn-NHRPVPN-tun100 down N/A N/A N/A N/A N/A
vyos@vyos:~$ show interfaces tunnel tun100
tun100@NONE: <MULTICAST,ALLMULTI,UP,LOWER_UP> mtu 1360 qdisc noqueue state UNKNOWN group default qlen 1000
link/gre 172.18.201.10 brd 0.0.0.0
inet 172.18.100.6/29 brd 172.18.100.7 scope global tun100
valid_lft forever preferred_lft forever
inet6 fe80::5efe:ac12:c90a/64 scope link
valid_lft forever preferred_lft forever
RX: bytes packets errors dropped overrun mcast
99016 990 0 0 0 0
TX: bytes packets errors dropped carrier collisions
95056 950 0 0 0 0
```