Connect to VPN on kali:

Install openconnect

sudo apt install openconnect

Connect:

sudo openconnect -u iron <server>
POST <server>
Connected to X.X.X.X:443
SSL negotiation with <server>
Connected to HTTPS on <server> with ciphersuite (TLS1.2)-(ECDHE-SECP256R1)-(RSA-SHA512)-(AES-256-GCM)
XML POST enabled
GROUP: [3rdParty-SSL-Client]:3rdParty-SSL-Client
POST <server>
XML POST enabled
Password:
POST <server>
Got CONNECT response: HTTP/1.1 200 OK
CSTP connected. DPD 30, Keepalive 20
Connected as 10.142.124.52, using SSL, with DTLS in progress
Established DTLS connection (using GnuTLS). Ciphersuite (DTLS1.2)-(ECDHE-RSA)-(AES-256-GCM).