The log repeatedly shows the critical error:

TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389

This indicates a fundamental mismatch between the client and server's security expectations during the TLS handshake phase.

The client configuration reveals several important details:

tls-auth ta.key 1
ns-cert-type server
proto tcp
remote openvpn1.flashvpn.com 3389

The client runs OpenVPN 2.0.9 (released in 2006), which predates modern HMAC handling:

OpenVPN 2.0.9 Win32-MinGW [SSL] [LZO] built on Oct 1 2006

First attempt - update the tls-auth directive:

# Replace:
tls-auth ta.key 1
# With:
tls-crypt ta.key

Second approach - modify protocol settings:

# Try UDP instead of TCP if possible
proto udp
remote openvpn1.flashvpn.com 1194

Here's a modified config with enhanced debugging:

client
dev tun
proto udp
remote openvpn1.flashvpn.com 1194
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
tls-crypt ta.key
auth-user-pass
verb 4
mute 10
sndbuf 393216
rcvbuf 393216
comp-lzo no
tun-mtu 1500
fragment 1300
mssfix

The server appears to be configured with:

• Port 3389 (typically RDP) instead of standard 1194
• Potential HMAC algorithm mismatch (SHA1 vs newer standards)
• Possible MTU/fragmentation issues

When testing connections, consider these command line options:

openvpn --config client.ovpn --tls-version-min 1.2 --tls-cipher TLS-ECDHE-RSA-WITH-AES-256-GCM-SHA384

---

When your OpenVPN client throws the error TLS Error: cannot locate HMAC in incoming packet, this indicates a fundamental mismatch in security expectations between client and server. The log shows repeated connection attempts to 67.228.223.12:3389 failing at the TLS handshake phase.

TLS Error: cannot locate HMAC in incoming packet from 67.228.223.12:3389
Fatal TLS error (check_tls_errors_co), restarting

This specific error occurs when:

• The server isn't sending HMAC-authenticated packets
• The client expects HMAC authentication (via tls-auth directive)
• Packet structure validation fails at the TLS layer

The client config shows critical security directives:

tls-auth ta.key 1
ns-cert-type server

Try these diagnostic steps:

1. Verify key synchronization:

   # On Linux/Mac:
   md5sum ta.key
   # On Windows:
   certutil -hashfile ta.key MD5
   

   Compare with server's ta.key hash

2. Protocol compatibility test:

   proto udp
   remote openvpn1.flashvpn.com 1194
   

   Many modern VPNs prefer UDP over TCP for OpenVPN

For OpenVPN 2.4+ servers, update your config:

client
dev tun
proto udp
remote openvpn1.flashvpn.com 1194
resolv-retry infinite
nobind
persist-key
persist-tun
remote-cert-tls server
tls-crypt ta.key
cipher AES-256-GCM
auth SHA256
comp-lzo no
verb 3

When the basic config fails:

# Packet capture command (Linux):
sudo tcpdump -i any -nn -v 'host 67.228.223.12 and port 3389'
# Windows alternative:
netsh trace start capture=yes tracefile=vpn.etl

Ensure your CA chain is properly configured:

openssl verify -CAfile ca.crt client.crt
# Expected output:
client.crt: OK

Your log shows OpenVPN 2.0.9 (2006 build) - consider upgrading as modern servers often require:

• TLS 1.2+ support
• AEAD cipher modes
• Improved HMAC implementations