OpenVPN 2.5+ - open-source VPN 2.5+

What is OpenVPN?

OpenVPN is an open-source VPN protocol that creates secure point-to-point or site-to-site connections. It uses SSL/TLS for key exchange and supports a wide range of encryption algorithms to protect data in transit. OpenVPN 2.5+ introduced several enhancements, including improved IPv6 support, better performance, and modern cryptographic options.

Why is OpenVPN important?

Secure Communication – Encrypts internet traffic to protect against eavesdropping and tampering.

Flexible Deployment – Works across platforms and supports both TCP and UDP transport.

Authentication Options – Supports username/password, certificates, and multi-factor authentication.

Widely Supported – Compatible with many operating systems, routers, and firewalls.

How OpenVPN works (in simple steps):

The client initiates a connection to the OpenVPN server.

A secure TLS handshake is performed to authenticate and exchange keys.

A secure tunnel is established using negotiated encryption.

Encrypted IP packets are exchanged between client and server through the tunnel.

Where is OpenVPN used?

Remote Workforce Access

Site-to-Site VPNs

Cloud Infrastructure Connectivity

Secure Wi-Fi Usage

Bypass Censorship and Geo-blocking

IoT and Embedded Systems

Which OSI Layer does this protocol belong to?

OpenVPN operates primarily at: * Transport Layer (Layer 4) – Uses TCP or UDP for transport. * Network Layer (Layer 3) – Encapsulates IP packets (IPv4/IPv6) for routing through the VPN tunnel.

Is OpenVPN 2.5+ Windows specific?

No, OpenVPN 2.5+ is not Windows-specific.
OpenVPN is a cross-platform VPN solution that supports Windows, Linux, macOS, Android, iOS, and more.
The 2.5+ series has improved performance, security, and support for newer encryption algorithms while maintaining broad platform compatibility.

Is OpenVPN 2.5+ Linux specific?

No, OpenVPN 2.5+ is not Linux-specific.
OpenVPN 2.5+ is also supported on Linux, as well as Windows, macOS, and other platforms.
Linux users often utilize OpenVPN through package managers or custom installation, as it is commonly used in server environments.

Which Transport Protocol is used by OpenVPN 2.5+?

OpenVPN 2.5+ uses UDP or TCP as transport protocols.
UDP is typically preferred for faster performance and lower latency in VPN tunnels.
However, OpenVPN 2.5+ can be configured to use TCP if UDP traffic is blocked by firewalls or for scenarios requiring more reliable, error-checked transmission.

Which Port is used by OpenVPN 2.5+?

By default, OpenVPN 2.5+ uses UDP port 1194.
If TCP is used instead, OpenVPN can be configured to use TCP port 443 (for better evasion of network filtering, as this is commonly used for HTTPS traffic).
Ports can be customized based on network restrictions and server/client configuration.

Is OpenVPN 2.5+ using Client-server model?

Yes, OpenVPN 2.5+ uses the client-server model.
The client (usually the user’s device) initiates a connection to the OpenVPN server, which then authenticates the client and creates a secure encrypted tunnel.
After successful authentication, data can be securely transmitted between the client and server.

Learnings in this section

In this section, you are going to learn

Terminology

Terminology

Version Info

Version Info

OpenVPN 2.5+ Version&RFC Details

OpenVPN 2.5+ Version	RFC	Year	Core Idea / Contribution
2.5.0
	Internal Spec	2020	Introduced –tls-crypt-v2, data-ciphers, ChaCha20-Poly1305 support, async auth, and deferred client-connect.
2.5.1-2.5.10
	Internal Spec	2021-2024	Bug fixes, OpenSSL compatibility updates, and minor enhancements.
2.6.0
	Internal Spec	2023	Added support for OpenSSL 3.0, improved IPv6 handling, and enhanced plugin interface.
2.6.x
	Internal Spec	20232024	Continued improvements in performance, security patches, and Windows GUI updates.

OpenVPN 2.5+ Basic Setup on Ubuntu using IPv4

Setup

OpenVPN 2.5+ Basic Setup on Ubuntu using IPv6

Setup

OpenVPN 2.5+ Protocol Packet Details

TLS Handshake Packet

S.No	Protocol Packets	Description	Size(Bytes)
1	TLS Handshake Packet	Initiates a secure session using SSL/TLS. Used for authentication and key exchange.	~100-1500 bytes
	Content Type	Indicates the type of TLS message (e.g., handshake, alert, application data).	1
	Version	TLS version (e.g., TLS 1.2 or 1.3).	2
	Length	Length of the TLS record.	2
	Handshake Type	Type of handshake message (e.g., ClientHello, ServerHello).	1
	Random	Random number used in key generation.	32
	Session ID	Optional session identifier.	Variable
	Cipher Suites	List of supported encryption algorithms.	Variable
	Extensions	Additional TLS features (e.g., SNI, ALPN).	Variable

Control Channel Packet

S.No	Protocol Packets	Description	Size(Bytes)
2	Control Channel Packet	Used for exchanging control messages (e.g., authentication, configuration)	~60-300 bytes
	Packet ID	Unique identifier for the control message	4
	Opcode	Indicates the type of control message (e.g., AUTH, PUSH_REQUEST)	1
	Payload	Encrypted control data	Variable

Data Channel Packet

S.No	Protocol Packets	Description	Size(Bytes)
3	Data Channel Packet	Carries encrypted user data (IP packets) after tunnel is established	Variable
	Packet Header	Includes flags, packet ID, and optional compression info	~4-8 bytes
	Encrypted Payload	User data (e.g., IP packets) encrypted using negotiated cipher	Variable
	HMAC	Message authentication code for integrity	16-32 bytes

Keepalive Packet

S.No	Protocol Packets	Description	Size(Bytes)
4	Keepalive Packet	Sent periodically to maintain the connection and detect dead peers	~1-4 bytes
	Opcode	Indicates a ping or pong message	1
	Timestamp	Optional timestamp for latency measurement	Variable

TLS Authentication Packet

S.No	Protocol Packets	Description	Size(Bytes)
5	TLS Authentication Packet	Optional packet used when tls-auth or tls-crypt is enabled	~60-100 bytes
	HMAC Signature	Verifies the authenticity of the TLS handshake	16-32 bytes
	Encrypted TLS Payload	TLS handshake data encrypted with a static key	Variable

OpenVPN 2.5+ Usecases

S.no	Use Case	Description
1	Website Access	Resolves domain names (e.g., example.com) to IP addresses so users can access websites
2	Email Routing	Uses MX (Mail Exchange) records to direct email traffic to the correct mail servers.
3	Load Balancing	Distributes traffic across multiple servers using DNS round-robin or geo-based records.
4	Content Delivery Networks (CDNs)	Directs users to the nearest server for faster content delivery using DNS-based redirection.
5	Service Discovery	Helps applications locate services (e.g., via SRV or TXT records), especially in microservices and enterprise networks.
6	Security Filtering	Blocks access to malicious domains using DNS-based firewalls or filtering services.
7	IoT Device Naming	Assigns human-readable names to devices in local or cloud-connected networks.
8	Failover and Redundancy	Automatically redirects traffic to backup servers if the primary server fails.

OpenVPN 2.5+ Basic Features

S.no	Feature	Description
1	Secure Tunneling	Encrypts traffic between client and server using TLS and modern ciphers like AES-GCM, ChaCha20
2	Protocol Flexibility	Supports both UDP and TCP transport protocols for adaptability across networks.
3	TLS Cryptography	Uses –tls-crypt and –tls-crypt-v2 to protect TLS handshake and prevent DoS attacks.
4	Cipher Negotiation	data-ciphers allows dynamic negotiation of encryption algorithms between peers.
5	Authentication Options	Supports certificate-based, username/password, PAM, and multi-factor authentication.
6	Asynchronous Authentication	Enables non-blocking auth plugins (e.g., PAM) for better scalability.
7	Client Configuration Push	Server can push routes, DNS settings, and other options to clients dynamically.
8	IPv6 Support	Full support for IPv6 transport and addressing within tunnels.
9	Compression (Deprecated)	Previously supported LZO compression; now discouraged due to security concerns.
10	High Availability	Supports failover and load balancing using multiple remote entries and client-side logic.

OpenVPN 2.5+ Feature : Secure Tunneling

Secure Tunneling - Testcases

#	Test Case	Description	Expected Result
1	VPN Connection Establishment	Initiate VPN connection using OpenVPN 2.5+	Connection established successfully
2	Authentication with Username/Password	Use valid credentials for authentication	Authentication successful
3	Authentication Failure	Use invalid credentials	Authentication fails with error
4	TLS Handshake	Verify TLS handshake during connection	TLS handshake completes successfully
5	Certificate Validation	Use valid client certificate	Certificate validated
6	Invalid Certificate	Use expired or invalid certificate	Connection rejected
7	UDP Protocol Test	Connect using UDP protocol	Connection established over UDP
8	TCP Protocol Test	Connect using TCP protocol	Connection established over TCP
9	Reconnect on Drop	Simulate network drop	VPN reconnects automatically
10	Data Encryption	Send data through tunnel	Data is encrypted
11	Data Integrity	Verify data integrity	No data corruption
12	DNS Leak Test	Check DNS requests	No DNS leaks
13	IP Leak Test	Check IP address visibility	Real IP is hidden
14	Kill Switch Test	Enable kill switch and drop VPN	Internet access blocked
15	Split Tunneling	Route specific traffic through VPN	Only selected traffic uses VPN
16	Full Tunnel Mode	Route all traffic through VPN	All traffic uses VPN
17	Compression Enabled	Enable compression	Data is compressed
18	Compression Disabled	Disable compression	Data is not compressed
19	Multiple Clients	Connect multiple clients	All clients connect successfully
20	Server Load Test	Simulate high load	Server handles load
21	Client Configuration File	Use .ovpn config file	Client connects successfully
22	Invalid Config File	Use malformed config	Connection fails
23	Log File Generation	Enable logging	Logs are generated
24	Log File Analysis	Check logs for errors	Errors are logged
25	Firewall Compatibility	Connect with firewall enabled	Connection succeeds
26	Port Forwarding	Enable port forwarding	Ports are forwarded
27	IPv6 Support	Use IPv6 address	VPN supports IPv6
28	IPv4 Support	Use IPv4 address	VPN supports IPv4
29	MTU Size Test	Change MTU size	Connection adapts
30	Packet Loss Simulation	Drop packets	VPN maintains connection
31	Latency Test	Measure latency	Latency within acceptable range
32	Bandwidth Test	Measure throughput	Bandwidth is stable
33	Roaming Test	Switch networks	VPN reconnects
34	Mobile Hotspot	Connect via hotspot	VPN connects
35	Public Wi-Fi	Connect on public Wi-Fi	VPN secures connection
36	Private Network	Connect on private LAN	VPN connects
37	VPN Server Restart	Restart server	Clients reconnect
38	Client Restart	Restart client	Reconnection successful
39	Time Synchronization	Check time sync	Time is synchronized
40	NAT Traversal	Connect behind NAT	VPN connects
41	Proxy Support	Use HTTP/SOCKS proxy	VPN connects via proxy
42	Custom Port	Use non-default port	VPN connects
43	TLS Version Test	Use TLS 1.2/1.3	Connection uses correct TLS
44	Cipher Suite Test	Use different ciphers	Connection uses selected cipher
45	Replay Attack Prevention	Replay packets	Packets rejected
46	Session Timeout	Idle session	Session times out
47	Keepalive Test	Enable keepalive	Connection stays alive
48	Client Certificate Revocation	Revoke cert	Connection denied
49	Server Certificate Expiry	Use expired server cert	Connection fails
50	Secure Tunneling Verification	Inspect tunnel traffic	Traffic is encrypted and secure

OpenVPN 2.5+ Feature : Protocol Flexibility

Protocol Flexibility - Testcases

#	Test Case	Description	Expected Result
1	Protocol Selection	Choose between TCP and UDP protocols	Protocol selected successfully
2	Default Protocol	Verify default protocol used by OpenVPN	UDP is used by default
3	TCP Connection	Establish VPN using TCP	VPN connects over TCP
4	UDP Connection	Establish VPN using UDP	VPN connects over UDP
5	Protocol Switch	Switch from TCP to UDP during session	Switch successful without disconnect
6	Protocol Switch Failure	Switch protocol with incompatible config	Switch fails with error
7	Protocol in Config File	Specify protocol in .ovpn file	Protocol applied correctly
8	Invalid Protocol	Use unsupported protocol	Connection fails with error
9	Protocol Port Mapping	Map protocol to correct port	Correct port used for protocol
10	Protocol Performance	Compare TCP vs UDP performance	UDP performs better in speed
11	Protocol Stability	Test stability of TCP and UDP	TCP more stable under packet loss
12	Protocol Latency	Measure latency for each protocol	UDP has lower latency
13	Protocol Throughput	Measure throughput for each protocol	UDP has higher throughput
14	Protocol with NAT	Use protocol behind NAT	Connection successful
15	Protocol with Firewall	Test protocol with firewall rules	Connection allowed or blocked
16	Protocol with Proxy	Use protocol with HTTP/SOCKS proxy	Connection successful
17	Protocol with VPN Server	Server supports both protocols	Client connects using either
18	Protocol with VPN Client	Client supports both protocols	Client connects using either
19	Protocol Failover	Failover from UDP to TCP	Failover successful
20	Protocol Timeout	Set timeout for protocol connection	Timeout enforced correctly
21	Protocol Retry	Retry connection on failure	Retry successful
22	Protocol Logging	Log protocol used in session	Protocol logged correctly
23	Protocol Encryption	Verify encryption over protocol	Encryption applied correctly
24	Protocol Compatibility	Test compatibility with OS	Protocol works on all OS
25	Protocol with IPv6	Use protocol over IPv6	Connection successful
26	Protocol with IPv4	Use protocol over IPv4	Connection successful
27	Protocol with Mobile	Connect using mobile network	Protocol adapts to mobile
28	Protocol with Wi-Fi	Connect using Wi-Fi	Protocol adapts to Wi-Fi
29	Protocol with Ethernet	Connect using Ethernet	Protocol adapts to Ethernet
30	Protocol with Roaming	Switch networks during session	Protocol maintains connection
31	Protocol with VPN Gateway	Use protocol with gateway	Connection successful
32	Protocol with VPN Tunnel	Verify tunnel creation	Tunnel created successfully
33	Protocol with VPN Routing	Route traffic via protocol	Traffic routed correctly
34	Protocol with VPN Policies	Apply policies per protocol	Policies enforced correctly
35	Protocol with VPN Load Balancing	Balance load across protocols	Load balanced successfully
36	Protocol with VPN Failover	Failover between protocols	Failover successful
37	Protocol with VPN Monitoring	Monitor protocol usage	Usage logged correctly
38	Protocol with VPN Alerts	Alert on protocol failure	Alert triggered
39	Protocol with VPN Metrics	Collect metrics per protocol	Metrics collected
40	Protocol with VPN QoS	Apply QoS per protocol	QoS enforced
41	Protocol with VPN Security	Verify security per protocol	Security measures applied
42	Protocol with VPN Updates	Update protocol settings	Settings updated
43	Protocol with VPN Automation	Automate protocol selection	Automation works
44	Protocol with VPN Scripts	Use scripts to set protocol	Scripts executed successfully
45	Protocol with VPN API	Set protocol via API	API sets protocol correctly
46	Protocol with VPN GUI	Select protocol via GUI	GUI reflects selection
47	Protocol with VPN CLI	Set protocol via CLI	CLI sets protocol correctly
48	Protocol with VPN Logs	Review logs for protocol	Logs show protocol used
49	Protocol with VPN Testing	Run tests per protocol	Tests pass
50	Protocol with VPN Documentation	Check docs for protocol support	Docs list supported protocols

OpenVPN 2.5+ Feature : TLS Cryptography

TLS Cryptography - Testcases

#	Test Case	Description	Expected Result
1	TLS Handshake Initiation	Initiate TLS handshake between client and server	Handshake starts successfully
2	TLS Handshake Completion	Complete TLS handshake	Handshake completes without error
3	TLS Version Support	Verify support for TLS 1.2 and 1.3	Both versions supported
4	TLS Cipher Negotiation	Negotiate cipher suite during handshake	Cipher suite agreed upon
5	TLS Certificate Validation	Validate server certificate	Certificate is valid
6	TLS Certificate Expiry	Use expired certificate	Connection fails with error
7	TLS Certificate Revocation	Use revoked certificate	Connection rejected
8	TLS Mutual Authentication	Use client and server certificates	Mutual authentication succeeds
9	TLS Key Exchange	Perform key exchange during handshake	Keys exchanged securely
10	TLS Session Resumption	Resume previous TLS session	Session resumed successfully
11	TLS Renegotiation	Trigger TLS renegotiation	Renegotiation completes
12	TLS Cryptographic Strength	Use strong cryptographic algorithms	Strong algorithms enforced
13	TLS Weak Cipher Rejection	Use weak cipher suite	Connection rejected
14	TLS Certificate Chain Validation	Validate full certificate chain	Chain is valid
15	TLS Certificate Pinning	Pin server certificate	Pinned certificate accepted
16	TLS Fingerprint Verification	Verify certificate fingerprint	Fingerprint matches
17	TLS Key Length Enforcement	Use minimum key length	Key length meets requirement
18	TLS Session Timeout	Idle TLS session	Session times out
19	TLS Session Logging	Log TLS session details	Session details logged
20	TLS Alert Handling	Trigger TLS alert	Alert handled correctly
21	TLS Error Reporting	Cause TLS error	Error reported in logs
22	TLS Protocol Downgrade Prevention	Attempt downgrade attack	Downgrade prevented
23	TLS Replay Attack Prevention	Replay TLS packets	Packets rejected
24	TLS MITM Attack Simulation	Simulate MITM attack	Attack detected or blocked
25	TLS Certificate Format	Use PEM format certificate	Certificate accepted
26	TLS Certificate with SAN	Use certificate with SubjectAltName	SAN validated
27	TLS Certificate without SAN	Use certificate without SAN	Connection fails
28	TLS OCSP Stapling	Enable OCSP stapling	OCSP response validated
29	TLS CRL Check	Use CRL for revocation check	Revoked certs rejected
30	TLS Session Key Rotation	Rotate session keys	Keys rotated securely
31	TLS with Static Key	Use static TLS key	Connection established
32	TLS with Dynamic Key	Use dynamic TLS key	Connection established
33	TLS with HMAC Authentication	Enable HMAC for TLS	HMAC verified
34	TLS with PSK	Use pre-shared key	Connection established
35	TLS with DH Parameters	Use Diffie-Hellman parameters	DH exchange successful
36	TLS with ECDHE	Use ECDHE for key exchange	ECDHE exchange successful
37	TLS with RSA	Use RSA for key exchange	RSA exchange successful
38	TLS with AES Encryption	Use AES cipher	AES encryption applied
39	TLS with ChaCha20	Use ChaCha20 cipher	ChaCha20 encryption applied
40	TLS with GCM Mode	Use GCM mode for encryption	GCM mode applied
41	TLS with CBC Mode	Use CBC mode for encryption	CBC mode applied
42	TLS with SHA256	Use SHA256 for hashing	SHA256 applied
43	TLS with SHA1	Use SHA1 for hashing	Connection rejected (weak hash)
44	TLS with Certificate Revocation List	Use CRL file	Revoked certs rejected
45	TLS with Intermediate CA	Use intermediate CA	Chain validated
46	TLS with Root CA	Use root CA	Root CA trusted
47	TLS with Self-signed Cert	Use self-signed certificate	Connection rejected
48	TLS with Valid SAN	Use SAN matching hostname	Connection accepted
49	TLS with Invalid SAN	Use SAN not matching hostname	Connection rejected
50	TLS Secure Tunnel Verification	Inspect tunnel traffic	Traffic is encrypted

OpenVPN 2.5+ Feature : Cipher Negotiation

Cipher Negotiation - Testcases

#	Test Case	Description	Expected Result
1	Default Cipher Usage	Verify default cipher used by OpenVPN 2.5+	Default cipher is AES-256-GCM
2	Custom Cipher Configuration	Specify a custom cipher in config	Custom cipher is used
3	Unsupported Cipher	Use an unsupported cipher	Connection fails with error
4	Cipher Negotiation Success	Client and server agree on cipher	Connection established
5	Cipher Negotiation Failure	No common cipher between client and server	Connection fails
6	Cipher Suite Logging	Log negotiated cipher suite	Cipher suite logged
7	Cipher Suite Priority	Set priority of cipher suites	Highest priority cipher used
8	Cipher Suite Order	Change order of cipher suites	Order respected during negotiation
9	Cipher Suite Compatibility	Test with older clients	Compatible cipher used
10	Cipher Downgrade Prevention	Prevent downgrade to weaker cipher	Downgrade blocked
11	Cipher Suite Upgrade	Upgrade to stronger cipher	Stronger cipher used
12	Cipher with TLS 1.2	Use cipher with TLS 1.2	Cipher negotiated successfully
13	Cipher with TLS 1.3	Use cipher with TLS 1.3	Cipher negotiated successfully
14	Cipher with Static Key	Use cipher in static key mode	Cipher applied correctly
15	Cipher with TLS Key	Use cipher in TLS key mode	Cipher applied correctly
16	Cipher with Compression	Enable compression with cipher	Cipher and compression work
17	Cipher without Compression	Disable compression	Only cipher applied
18	Cipher with Auth Algorithm	Use specific auth algorithm	Auth algorithm applied
19	Cipher without Auth	Disable auth algorithm	Only cipher applied
20	Cipher with HMAC	Use HMAC with cipher	HMAC applied correctly
21	Cipher with AEAD	Use AEAD cipher	AEAD cipher applied
22	Cipher with CBC	Use CBC mode cipher	CBC cipher applied
23	Cipher with GCM	Use GCM mode cipher	GCM cipher applied
24	Cipher with ChaCha20	Use ChaCha20 cipher	ChaCha20 cipher applied
25	Cipher with AES	Use AES cipher	AES cipher applied
26	Cipher with DES	Use DES cipher	Connection rejected (weak cipher)
27	Cipher with 3DES	Use 3DES cipher	Connection rejected (weak cipher)
28	Cipher with Blowfish	Use Blowfish cipher	Blowfish cipher applied
29	Cipher with Camellia	Use Camellia cipher	Camellia cipher applied
30	Cipher with Null Cipher	Use null cipher	Connection rejected
31	Cipher with Invalid Config	Use malformed cipher config	Connection fails
32	Cipher with Multiple Clients	Negotiate cipher with multiple clients	Each client negotiates successfully
33	Cipher with Server Push	Server pushes cipher to client	Client accepts pushed cipher
34	Cipher with Client Push	Client pushes cipher to server	Server accepts pushed cipher
35	Cipher with VPN Gateway	Negotiate cipher with gateway	Cipher applied correctly
36	Cipher with VPN Tunnel	Verify cipher in tunnel	Tunnel encrypted with cipher
37	Cipher with VPN Routing	Route traffic with cipher	Traffic encrypted
38	Cipher with VPN Policy	Apply policy based on cipher	Policy enforced
39	Cipher with VPN Monitoring	Monitor cipher usage	Cipher usage logged
40	Cipher with VPN Alerts	Alert on weak cipher usage	Alert triggered
41	Cipher with VPN Metrics	Collect cipher metrics	Metrics collected
42	Cipher with VPN QoS	Apply QoS per cipher	QoS enforced
43	Cipher with VPN Security	Verify security of cipher	Cipher meets security standards
44	Cipher with VPN Updates	Update cipher settings	Settings updated
45	Cipher with VPN Automation	Automate cipher selection	Automation works
46	Cipher with VPN Scripts	Use script to set cipher	Script executed successfully
47	Cipher with VPN API	Set cipher via API	API sets cipher correctly
48	Cipher with VPN GUI	Select cipher via GUI	GUI reflects selection
49	Cipher with VPN CLI	Set cipher via CLI	CLI sets cipher correctly
50	Cipher Suite Documentation	Check docs for cipher support	Docs list supported ciphers

OpenVPN 2.5+ Feature : Authentication Options

Authentication Options - Testcases

#	Test Case	Description	Expected Result
1	Username/Password Authentication	Authenticate using valid username and password	Authentication successful
2	Invalid Username	Use incorrect username	Authentication fails
3	Invalid Password	Use incorrect password	Authentication fails
4	Empty Credentials	Leave username and password blank	Authentication fails
5	Certificate Authentication	Authenticate using valid client certificate	Authentication successful
6	Invalid Certificate	Use expired or invalid certificate	Authentication fails
7	Revoked Certificate	Use a revoked certificate	Authentication fails
8	Mutual TLS Authentication	Use both client and server certificates	Mutual authentication successful
9	Static Key Authentication	Use static key for authentication	Connection established
10	Missing Static Key	Omit static key in config	Connection fails
11	Two-Factor Authentication	Use 2FA with OTP	Authentication successful
12	Invalid OTP	Use incorrect OTP	Authentication fails
13	LDAP Authentication	Authenticate using LDAP credentials	Authentication successful
14	Invalid LDAP Credentials	Use incorrect LDAP credentials	Authentication fails
15	RADIUS Authentication	Authenticate using RADIUS server	Authentication successful
16	RADIUS Server Unavailable	Disconnect RADIUS server	Authentication fails
17	SAML Authentication	Authenticate using SAML provider	Authentication successful
18	Invalid SAML Token	Use expired SAML token	Authentication fails
19	OAuth Authentication	Authenticate using OAuth provider	Authentication successful
20	Invalid OAuth Token	Use invalid OAuth token	Authentication fails
21	Client Certificate with Password	Use certificate and password	Authentication successful
22	Password Expiry	Use expired password	Authentication fails
23	Password Complexity	Use weak password	Authentication fails
24	Password Change	Change password and re-authenticate	Authentication successful
25	Authentication Retry	Retry after failed attempt	Authentication successful
26	Authentication Lockout	Exceed max failed attempts	Account locked
27	Authentication Logging	Enable logging for authentication	Logs show authentication events
28	Authentication Timeout	Delay response beyond timeout	Authentication fails
29	Authentication via API	Authenticate using API call	Authentication successful
30	Authentication via GUI	Authenticate using GUI client	Authentication successful
31	Authentication via CLI	Authenticate using command line	Authentication successful
32	Authentication with VPN Gateway	Authenticate through gateway	Authentication successful
33	Authentication with VPN Tunnel	Verify authentication within tunnel	Tunnel established after authentication
34	Authentication with VPN Policy	Apply policy based on user	Policy enforced
35	Authentication with VPN Role	Assign role after authentication	Role assigned
36	Authentication with VPN Group	Authenticate as group member	Group access granted
37	Authentication with VPN Script	Use script to validate credentials	Script executed and validated
38	Authentication with VPN Plugin	Use plugin for authentication	Plugin authenticates successfully
39	Authentication with VPN Profile	Use user profile for authentication	Profile loaded and authenticated
40	Auth with Certificate Revocation List	Use CRL to validate cert	Revoked certs rejected
41	Authentication with VPN OCSP	Use OCSP to validate cert	OCSP response validated
42	Authentication with VPN MFA	Use multi-factor authentication	Authentication successful
43	Authentication with VPN Biometric	Use biometric for authentication	Authentication successful
44	Authentication with VPN Smart Card	Use smart card for authentication	Authentication successful
45	Authentication with VPN Token	Use hardware token	Authentication successful
46	Auth with Environment Variable	Use env variable for credentials	Authentication successful
47	Auth with Config File	Store credentials in config	Authentication successful
48	Auth with Session Cache	Reuse session credentials	Authentication successful
49	Auth with Failover	Failover to backup auth server	Authentication successful
50	Auth Documentation	Check documentation for auth options	Options listed in docs

OpenVPN 2.5+ Feature : Asynchronous Authentication

Asynchronous Authentication - Testcases

#	Test Case	Description	Expected Result
1	Async Auth Enable	Enable asynchronous authentication in server config	Server accepts async auth requests
2	Async Auth Plugin Load	Load external auth plugin for async auth	Plugin loaded successfully
3	Async Auth Script Execution	Execute external script for auth	Script runs and returns result
4	Async Auth Success	Authenticate with valid credentials asynchronously	Authentication successful
5	Async Auth Failure	Authenticate with invalid credentials asynchronously	Authentication fails
6	Async Auth Timeout	Simulate delay in auth response	Authentication times out
7	Async Auth Retry	Retry auth after failure	Authentication succeeds on retry
8	Async Auth Logging	Enable logging for async auth	Logs show auth events
9	Async Auth with TLS	Use TLS with async auth	TLS and auth succeed
10	Async Auth with Static Key	Use static key with async auth	Connection established
11	Async Auth with Cert	Use client certificate with async auth	Authentication successful
12	Async Auth with Username/Password	Use credentials with async auth	Authentication successful
13	Async Auth with 2FA	Use OTP with async auth	Authentication successful
14	Async Auth with LDAP	Use LDAP backend for async auth	LDAP auth successful
15	Async Auth with RADIUS	Use RADIUS backend for async auth	RADIUS auth successful
16	Async Auth with OAuth	Use OAuth token for async auth	OAuth auth successful
17	Async Auth with SAML	Use SAML token for async auth	SAML auth successful
18	Async Auth with API	Call external API for auth	API returns auth result
19	Async Auth with JSON	Send/receive JSON in auth	JSON parsed successfully
20	Async Auth with XML	Send/receive XML in auth	XML parsed successfully
21	Async Auth with Delay	Introduce delay in auth response	Server handles delay
22	Async Auth with Error	Return error from auth script	Connection rejected
23	Async Auth with Logging Enabled	Enable verbose logging	Detailed logs generated
24	Async Auth with Logging Disabled	Disable logging	No logs generated
25	Async Auth with Multiple Clients	Authenticate multiple clients asynchronously	All clients authenticated
26	Async Auth with Concurrent Requests	Send concurrent auth requests	All requests handled
27	Async Auth with Large Payload	Send large auth payload	Payload processed
28	Async Auth with Invalid Payload	Send malformed payload	Authentication fails
29	Async Auth with Token Expiry	Use expired token	Authentication fails
30	Async Auth with Token Refresh	Refresh token before expiry	Authentication succeeds
31	Async Auth with Session Cache	Cache session after auth	Session reused
32	Async Auth with Session Timeout	Expire session after timeout	Re-authentication required
33	Async Auth with Role Mapping	Map user to role after auth	Role assigned
34	Async Auth with Group Mapping	Map user to group after auth	Group assigned
35	Async Auth with Policy Enforcement	Apply policy after auth	Policy enforced
36	Async Auth with Access Control	Restrict access based on auth	Access granted/denied
37	Async Auth with VPN Gateway	Authenticate via gateway	Authentication successful
38	Async Auth with VPN Tunnel	Verify tunnel after auth	Tunnel established
39	Async Auth with VPN Client	Use client with async auth	Client connects
40	Async Auth with VPN Server	Use server with async auth	Server handles auth
41	Async Auth with Failover	Failover to backup auth server	Authentication succeeds
42	Async Auth with Load Balancer	Balance auth requests	Requests distributed
43	Async Auth with Monitoring	Monitor auth events	Events logged
44	Async Auth with Alerts	Trigger alert on auth failure	Alert sent
45	Async Auth with Metrics	Collect auth metrics	Metrics recorded
46	Async Auth with GUI	Use GUI to configure auth	Settings applied
47	Async Auth with CLI	Use CLI to configure auth	Settings applied
48	Async Auth with Config File	Configure auth in .conf file	Settings loaded
49	Async Auth with Documentation	Check docs for async auth	Docs list feature
50	Async Auth with Version Check	Verify OpenVPN version	Feature supported in 2.5+

OpenVPN 2.5+ Feature : Client Configuration Push

Client Configuration Push - Testcases

#	Test Case	Description	Expected Result
1	Push DNS Configuration	Server pushes DNS settings to client	Client uses pushed DNS settings
2	Push Route Configuration	Server pushes routing rules to client	Client routes traffic accordingly
3	Push Redirect Gateway	Server pushes redirect-gateway option	Client routes all traffic through VPN
4	Push Custom Script	Server pushes script execution command	Client executes script on connect
5	Push MTU Settings	Server pushes MTU size	Client applies MTU setting
6	Push IP Address	Server pushes IP address	Client uses assigned IP
7	Push Subnet Mask	Server pushes subnet mask	Client configures subnet correctly
8	Push Domain Name	Server pushes domain name	Client sets domain name
9	Push WINS Server	Server pushes WINS server address	Client uses WINS server
10	Push NTP Server	Server pushes NTP server address	Client syncs time with NTP server
11	Push Proxy Settings	Server pushes proxy configuration	Client uses proxy settings
12	Push Firewall Rules	Server pushes firewall rules	Client applies firewall rules
13	Push Static Routes	Server pushes static routes	Client adds static routes
14	Push Dynamic Routes	Server pushes dynamic routes	Client adds dynamic routes
15	Push DNS Suffix	Server pushes DNS suffix	Client appends suffix to DNS queries
16	Push Search Domain	Server pushes search domain	Client uses search domain
17	Push Environment Variables	Server pushes env variables	Client sets environment variables
18	Push Client Script	Server pushes client-connect script	Client executes script on connect
19	Push Disconnect Script	Server pushes disconnect script	Client executes script on disconnect
20	Push Reconnect Script	Server pushes reconnect script	Client executes script on reconnect
21	Push Custom Config File	Server pushes custom config file	Client loads config file
22	Push Log Settings	Server pushes log level settings	Client sets log level
23	Push Compression Settings	Server pushes compression options	Client applies compression
24	Push Cipher Settings	Server pushes cipher configuration	Client uses specified cipher
25	Push Auth Settings	Server pushes authentication method	Client uses specified auth method
26	Push Keepalive Settings	Server pushes keepalive parameters	Client applies keepalive settings
27	Push Ping Settings	Server pushes ping interval	Client sends pings accordingly
28	Push Ping Restart Settings	Server pushes ping-restart value	Client restarts connection on timeout
29	Push TLS Settings	Server pushes TLS options	Client uses TLS settings
30	Push Session Timeout	Server pushes session timeout	Client disconnects after timeout
31	Push Renegotiation Interval	Server pushes reneg-sec value	Client renegotiates session
32	Push Replay Protection	Server pushes replay protection settings	Client enables replay protection
33	Push Fragment Settings	Server pushes fragment size	Client fragments packets accordingly
34	Push MSS Fix	Server pushes mssfix value	Client applies MSS fix
35	Push TUN/TAP Mode	Server pushes tun/tap mode	Client configures interface accordingly
36	Push Interface Name	Server pushes interface name	Client uses specified interface
37	Push IPv6 Settings	Server pushes IPv6 configuration	Client applies IPv6 settings
38	Push IPv4 Settings	Server pushes IPv4 configuration	Client applies IPv4 settings
39	Push Push-Reset	Server sends push-reset command	Client resets pushed options
40	Push Push-Reply	Server sends push-reply message	Client applies pushed options
41	Push Multiple Options	Server pushes multiple options	Client applies all options
42	Push Invalid Option	Server pushes invalid option	Client ignores or logs error
43	Push Option with Delay	Server delays push message	Client waits and applies options
44	Push Option with Timeout	Push message times out	Client uses default settings
45	Push Option with Retry	Server retries push message	Client applies on retry
46	Push Option with Logging	Enable logging of push options	Client logs received options
47	Push Option with GUI	Client GUI displays pushed options	User sees applied settings
48	Push Option with CLI	Client CLI shows pushed options	Options visible in CLI output
49	Push Option with API	Client API receives push options	Options applied via API
50	Push Option Documentation	Check documentation for push options	Options listed and explained

OpenVPN 2.5+ Feature : IPv6 Support

IPv6 Support - Testcases

#	Test Case	Description	Expected Result
1	IPv6 Tunnel Establishment	Establish VPN tunnel using IPv6	Tunnel established successfully
2	IPv6 Address Assignment	Assign IPv6 address to client	Client receives IPv6 address
3	IPv6 Routing	Push IPv6 routes to client	Client routes traffic via IPv6
4	IPv6 DNS Resolution	Resolve domain names over IPv6	DNS resolution successful
5	IPv6 Only Network	Connect from IPv6-only network	VPN connection successful
6	Dual Stack Network	Connect from dual stack (IPv4/IPv6) network	VPN uses IPv6 preferentially
7	IPv6 Traffic Encryption	Send IPv6 traffic through tunnel	Traffic is encrypted
8	IPv6 Leak Test	Check for IPv6 leaks	No IPv6 leaks detected
9	IPv6 Firewall Rules	Apply firewall rules for IPv6	Rules enforced correctly
10	IPv6 NAT Traversal	Connect through NAT with IPv6	Connection successful
11	IPv6 MTU Handling	Test MTU size with IPv6	MTU handled correctly
12	IPv6 Fragmentation	Send fragmented IPv6 packets	Packets reassembled correctly
13	IPv6 Compression	Enable compression with IPv6	Compression applied
14	IPv6 with TLS	Use TLS with IPv6 transport	TLS handshake successful
15	IPv6 with UDP	Use UDP over IPv6	Connection established
16	IPv6 with TCP	Use TCP over IPv6	Connection established
17	IPv6 with Static Key	Use static key with IPv6	Connection established
18	IPv6 with Certificates	Use certificates with IPv6	Authentication successful
19	IPv6 with Username/Password	Use credentials with IPv6	Authentication successful
20	IPv6 with 2FA	Use two-factor authentication with IPv6	Authentication successful
21	IPv6 Reconnect	Reconnect after IPv6 drop	Reconnection successful
22	IPv6 Roaming	Switch IPv6 networks	VPN reconnects automatically
23	IPv6 Performance	Measure performance over IPv6	Performance within expected range
24	IPv6 Latency	Measure latency over IPv6	Latency within acceptable limits
25	IPv6 Throughput	Measure throughput over IPv6	Throughput is stable
26	IPv6 Packet Loss	Simulate packet loss	VPN maintains connection
27	IPv6 Session Timeout	Idle session over IPv6	Session times out correctly
28	IPv6 Keepalive	Enable keepalive over IPv6	Connection stays alive
29	IPv6 Logging	Log IPv6 session details	Logs contain IPv6 info
30	IPv6 Metrics	Collect metrics for IPv6 sessions	Metrics recorded
31	IPv6 Alerts	Trigger alert on IPv6 failure	Alert generated
32	IPv6 Monitoring	Monitor IPv6 traffic	Traffic visible in monitor
33	IPv6 Failover	Failover from IPv6 to IPv4	Failover successful
34	IPv6 Load Balancing	Balance load over IPv6	Load balanced correctly
35	IPv6 QoS	Apply QoS to IPv6 traffic	QoS enforced
36	IPv6 Policy Enforcement	Enforce policy on IPv6 clients	Policy applied
37	IPv6 Access Control	Restrict access via IPv6	Access controlled
38	IPv6 Certificate Revocation	Revoke IPv6 client cert	Connection denied
39	IPv6 CRL Check	Use CRL with IPv6 certs	Revoked certs rejected
40	IPv6 OCSP Stapling	Enable OCSP for IPv6 certs	OCSP response validated
41	IPv6 with GUI Client	Connect using GUI over IPv6	Connection successful
42	IPv6 with CLI Client	Connect using CLI over IPv6	Connection successful
43	IPv6 with Mobile Client	Connect from mobile over IPv6	Connection successful
44	IPv6 with Desktop Client	Connect from desktop over IPv6	Connection successful
45	IPv6 with VPN Gateway	Use IPv6 with VPN gateway	Traffic routed via gateway
46	IPv6 with VPN Tunnel	Verify tunnel over IPv6	Tunnel established
47	IPv6 with VPN Server	Server listens on IPv6	Server accepts IPv6 connections
48	IPv6 with VPN Client	Client initiates IPv6 connection	Client connects successfully
49	IPv6 Documentation	Check docs for IPv6 support	IPv6 options documented
50	IPv6 Compatibility	Test compatibility with OS	IPv6 works on all platforms

OpenVPN 2.5+ Feature : Compression (Deprecated)

Compression (Deprecated) - Testcases

#	Test Case	Description	Expected Result
1	Enable Compression	Enable compression in server config	Compression enabled
2	Disable Compression	Disable compression in server config	Compression disabled
3	Client Accepts Compression	Client accepts compression from server	Compression applied
4	Client Rejects Compression	Client rejects compression from server	Compression not applied
5	Compression with TLS	Use compression with TLS connection	Connection established with compression
6	Compression with UDP	Use compression over UDP	Compression applied successfully
7	Compression with TCP	Use compression over TCP	Compression applied successfully
8	Compression with Static Key	Use compression in static key mode	Compression applied
9	Compression with Certificates	Use compression with certificate authentication	Compression applied
10	Compression with Username/Password	Use compression with credential authentication	Compression applied
11	Compression with Large Payload	Send large data payload	Payload compressed
12	Compression with Small Payload	Send small data payload	Minimal compression benefit
13	Compression with Fragmentation	Enable fragmentation with compression	Packets fragmented and compressed
14	Compression with MTU	Test MTU size with compression	MTU adjusted correctly
15	Compression with MSS Fix	Enable mssfix with compression	MSS fix applied
16	Compression with Replay Protection	Enable replay protection	Replay protection works with compression
17	Compression with Keepalive	Enable keepalive	Connection maintained with compression
18	Compression with Ping	Send ping packets	Ping packets compressed
19	Compression with Renegotiation	Trigger session renegotiation	Compression persists
20	Compression with Session Timeout	Idle session with compression	Session times out correctly
21	Compression with IPv6	Use compression over IPv6	Compression applied
22	Compression with IPv4	Use compression over IPv4	Compression applied
23	Compression with Dual Stack	Use dual stack network	Compression applied on both stacks
24	Compression with NAT	Connect through NAT	Compression applied
25	Compression with Firewall	Enable firewall	Compression traffic allowed
26	Compression with Proxy	Use proxy server	Compression applied
27	Compression with Mobile Client	Connect from mobile device	Compression applied
28	Compression with Desktop Client	Connect from desktop	Compression applied
29	Compression with GUI Client	Use GUI client	Compression settings visible
30	Compression with CLI Client	Use CLI client	Compression settings applied
31	Compression with API	Configure compression via API	Compression enabled
32	Compression with Config File	Set compression in config file	Compression applied
33	Compression with Script	Use script to enable compression	Script executes successfully
34	Compression with Plugin	Use plugin to manage compression	Plugin applies compression
35	Compression with Logging	Enable logging	Compression events logged
36	Compression with Monitoring	Monitor compression traffic	Traffic visible in monitor
37	Compression with Alerts	Trigger alert on compression failure	Alert generated
38	Compression with Metrics	Collect compression metrics	Metrics recorded
39	Compression with Performance Test	Measure performance with compression	Improved throughput
40	Compression with Latency Test	Measure latency with compression	Latency reduced
41	Compression with Packet Loss	Simulate packet loss	Compression maintains connection
42	Compression with Load Balancer	Use load balancer	Compression applied across nodes
43	Compression with VPN Gateway	Use VPN gateway	Compression applied
44	Compression with VPN Tunnel	Verify tunnel with compression	Tunnel encrypted and compressed
45	Compression with VPN Server	Server supports compression	Compression enabled
46	Compression with VPN Client	Client supports compression	Compression enabled
47	Compression with Deprecated Warning	Check for deprecation warning	Warning displayed
48	Compression with Compatibility Test	Test compatibility with older clients	Compression works
49	Compression with Documentation	Check documentation for compression	Feature marked deprecated
50	Compression Disabled by Default	Verify default compression setting	Compression disabled by default

OpenVPN 2.5+ Feature : High Availability

High Availability - Testcases

#	Test Case	Description	Expected Result
1	Enable HA Mode	Enable high availability mode in OpenVPN server	HA mode enabled successfully
2	Primary Server Start	Start the primary OpenVPN server	Primary server starts and accepts connections
3	Secondary Server Start	Start the secondary OpenVPN server	Secondary server starts and waits in standby
4	Failover Trigger	Simulate primary server failure	Secondary server takes over
5	Failback to Primary	Restore primary server	Primary resumes control
6	Load Balancing Enabled	Enable load balancing between servers	Traffic distributed across servers
7	Session Persistence	Maintain session during failover	Session continues without interruption
8	Heartbeat Monitoring	Monitor heartbeat between servers	Heartbeat detected and monitored
9	Heartbeat Failure Detection	Stop heartbeat from primary	Secondary detects failure and activates
10	HA Configuration File	Use HA config file for setup	Configuration applied successfully
11	HA Logging	Enable logging for HA events	Logs show HA transitions
12	HA Alerts	Trigger alert on failover	Alert generated
13	HA Metrics	Collect metrics on HA performance	Metrics recorded
14	HA with TLS	Use TLS with HA setup	TLS handshake successful on both servers
15	HA with UDP	Use UDP protocol in HA	UDP traffic handled by active server
16	HA with TCP	Use TCP protocol in HA	TCP traffic handled by active server
17	HA with IPv6	Use IPv6 in HA setup	IPv6 traffic routed correctly
18	HA with IPv4	Use IPv4 in HA setup	IPv4 traffic routed correctly
19	HA with Dual Stack	Use dual stack networking	Both IPv4 and IPv6 supported
20	HA with NAT	Use NAT in HA setup	NAT traversal works correctly
21	HA with Firewall	Enable firewall rules	HA traffic allowed
22	HA with VPN Gateway	Use HA with VPN gateway	Gateway handles failover
23	HA with VPN Tunnel	Verify tunnel during failover	Tunnel remains active
24	HA with VPN Client	Client connects during failover	Client reconnects to active server
25	HA with Load Balancer	Use external load balancer	Load balancer redirects traffic
26	HA with DNS Failover	Use DNS for failover	DNS resolves to active server
27	HA with Keepalive	Enable keepalive in HA	Keepalive maintains connection
28	HA with Session Timeout	Test session timeout	Session expires as configured
29	HA with Reconnect	Reconnect after failover	Client reconnects automatically
30	HA with Monitoring Tool	Use monitoring tool for HA	Tool shows server status
31	HA with Alerts System	Integrate with alert system	Alerts sent on failover
32	HA with Metrics Export	Export HA metrics	Metrics exported successfully
33	HA with GUI	Configure HA via GUI	Settings applied via GUI
34	HA with CLI	Configure HA via CLI	Settings applied via CLI
35	HA with API	Configure HA via API	API applies settings
36	HA with Config Reload	Reload config without restart	Config reloaded successfully
37	HA with Certificate Rotation	Rotate certificates	HA continues without disruption
38	HA with Log Rotation	Rotate logs	Logs rotated without affecting HA
39	HA with Backup Server	Add backup server	Backup server joins HA cluster
40	HA with Multiple Clients	Connect multiple clients	All clients handled during failover
41	HA with VPN Policies	Apply policies in HA	Policies enforced on active server
42	HA with Role Mapping	Map roles in HA	Roles applied correctly
43	HA with Group Mapping	Map groups in HA	Groups applied correctly
44	HA with Access Control	Restrict access in HA	Access controlled correctly
45	HA with Certificate Revocation	Revoke cert in HA	Revoked cert denied
46	HA with OCSP	Enable OCSP in HA	OCSP responses validated
47	HA with CRL	Use CRL in HA	Revoked certs rejected
48	HA with Performance Test	Measure performance in HA	Performance within expected range
49	HA with Stress Test	Simulate high load	HA handles load
50	HA Documentation Check	Review HA documentation	All features documented

Reference links

Reference links