Technical Specs

We provide ONLY protocol/servers.

• OpenVPN >=2.4, negotiation with following ciphers (ncp-ciphers directive server-side):
  AES-256-GCM AES-256-CBC AES-256-CFB AES-256-OFB AES-256-CFB1 AES-256-CFB8 AES-128-GCM AES-128-CBC AES-128-CFB AES-128-OFB AES-128-CFB1 AES-128-CFB8 CAMELLIA-256-CBC SEED-CBC
  OpenVPN <2.4, AES-256-CBC as data channel cipher.
• Negotiation with following TLS ciphers (IANA names, tls-cipher directive server-side):
  TLS-DHE-RSA-WITH-AES-256-GCM-SHA384 TLS-DHE-RSA-WITH-AES-256-CBC-SHA256 TLS-DHE-RSA-WITH-AES-256-CBC-SHA TLS-DHE-RSA-WITH-CAMELLIA-256-CBC-SHA
  Unlike the OpenVPN default, we don't accept any AES-128 or any TLS-ECDHE.
• Perfect Forward Secrecy through Diffie-Hellman key exchange DHE. After the initial key negotiation, re-keying is performed every 60 minutes (this value can be lowered unilaterally by the client)
• 4096 bit RSA keys size
• 4096 bit Diffie-Hellman keys size (unique for each server, VPN or webserver)

• Encrypt and authenticate all control channel packets (tls-crypt directive) with 2048 bit.
• SHA512 message digest (if the negotiated cipher is not AEAD, e.g. GCM).

• TLS additional authorization layer key (tls-auth directive): 2048 bit
• HMAC-SHA1 for authentication

Multiple entry ports (53, 80, 443, 1194, 2018, 28439, 38915, 41185), native OpenVPN tcp/udp or with additional tunnel layers (SSL, SSH).

Servers support both IPv4 and IPv6 tunnel (exit-ip), and are reachable over IPv4 and IPv6 (entry-ip). Currently (2018/01) not all servers support IPv6 tunnel yet.
DNS server address is the same as gateway, in both IPv4 and IPv6 layer.

IPv4 Local Address chosen: 10.{daemon}.*.*, Subnet-Mask: 255.255.255.0
IPv6 Unique Local Address (ULA) chosen: fde6:7a:7d20:{daemon}::/48.

• Outbound port 25 blocked to prevent spam.

• Every VPN server has its DNS server, directly finds out information about the root servers, top level domains and authoritative name servers.
• Our DNS servers are neutral, do not ever inject or alter the requests (other services resolve to search results, try to fix typo etc).
• Where ICANN or root servers themselves interfer with censorship, we may apply specific censorship fix to our DNS server. See "AirVPN does not recognize ICANN authority anymore" topic for more informations.
• Using our DNS allows our customers to use our anti-geolocation discrimination features. For example, visit a website that allows only United States connections from a Netherlands VPN server.
• It's recommended to use our DNS server to avoid censorship and use our anti-geolocation features.
• VPN DNS addresses (private addresses, only reachable from inside the VPN): 10.4.0.1 / fde6:7a:7d20:4::1 - reachable from any virtual subnet
  However, we recommend that your machine accepts the DNS push from our servers. If that's not possible, then we suggest to set the DNS IP address matching the VPN gateway IP address, as this is the safest method to prevent certain attacks based on hijacking.
• For any kind of issue about censorship or geolocation restriction you encounter using our services, please feel free to write us in our forums or write a support ticket.

Every AirVPN server has 4 entry-IPv4 addresses and 4 entry-IPv6 addresses that support different ports and protocols. Look at the faq "How can I get VPN servers entry-IP addresses?" for more information about FQDN resolution.

Entry IP	Protocol	Port	Specs	Description	Min. OpenVPN version
1	udp	443		Recommended for best performance
1	tcp	443		If you have issue with UDP
1	udp	80		If your ISP applies caps or blocks
1	tcp	80		If your ISP applies caps or blocks
1	udp	53		If your ISP applies caps or blocks
1	tcp	53		If your ISP applies caps or blocks
1	udp	2018		If your ISP applies caps or blocks
1	tcp	2018		If your ISP applies caps or blocks
2	udp	443		If your ISP blocks the standard Entry IP
2	udp	80		If your ISP blocks the standard Entry IP
2	udp	53		If your ISP blocks the standard Entry IP
2	udp	2018		If your ISP blocks the standard Entry IP
2	tcp	2018		If your ISP blocks the standard Entry IP
1	ssh	22		If your ISP applies caps or blocks
2	ssh	22		If your ISP blocks the standard Entry IP
2	ssh	80		If your ISP applies caps or blocks
2	ssh	53		If your ISP applies caps or blocks
2	ssl	443		If your ISP applies caps or blocks
1	udp	1194		Official OpenVPN port
1	tcp	1194		Official OpenVPN port
1	udp	41185		If your ISP applies caps or blocks on lower port ranges
1	tcp	41185		If your ISP applies caps or blocks on lower port ranges
1	ssh	38915		If your ISP applies caps or blocks on lower port ranges
1	ssl	28439		If your ISP applies caps or blocks on lower port ranges
2	udp	1194		Official OpenVPN port, if your ISP blocks the standard Entry IP
2	tcp	1194		Official OpenVPN port, if your ISP blocks the standard Entry IP
2	udp	41185		If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP
2	tcp	41185		If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP
2	ssh	38915		If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP
2	ssl	28439		If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP
3	udp	443	tls-crypt, tls1.2	Recommended for best performance	2.4
3	tcp	443	tls-crypt, tls1.2	If you have issue with UDP	2.4
3	udp	80	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
3	tcp	80	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
3	udp	53	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
3	tcp	53	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
3	udp	2018	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
3	tcp	2018	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
4	udp	443	tls-crypt, tls1.2	If your ISP blocks the standard Entry IP	2.4
4	udp	80	tls-crypt, tls1.2	If your ISP blocks the standard Entry IP	2.4
4	udp	53	tls-crypt, tls1.2	If your ISP blocks the standard Entry IP	2.4
4	udp	2018	tls-crypt, tls1.2	If your ISP blocks the standard Entry IP	2.4
4	tcp	2018	tls-crypt, tls1.2	If your ISP blocks the standard Entry IP	2.4
3	ssh	22	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
4	ssh	22	tls-crypt, tls1.2	If your ISP blocks the standard Entry IP	2.4
4	ssh	80	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
4	ssh	53	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
4	ssl	443	tls-crypt, tls1.2	If your ISP applies caps or blocks	2.4
3	udp	1194	tls-crypt, tls1.2	Official OpenVPN port	2.4
3	tcp	1194	tls-crypt, tls1.2	Official OpenVPN port	2.4
3	udp	41185	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges	2.4
3	tcp	41185	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges	2.4
3	ssh	38915	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges	2.4
3	ssl	28439	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges	2.4
4	udp	1194	tls-crypt, tls1.2	Official OpenVPN port, if your ISP blocks the standard Entry IP	2.4
4	tcp	1194	tls-crypt, tls1.2	Official OpenVPN port, if your ISP blocks the standard Entry IP	2.4
4	udp	41185	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP	2.4
4	tcp	41185	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP	2.4
4	ssh	38915	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP	2.4
4	ssl	28439	tls-crypt, tls1.2	If your ISP applies caps or blocks on lower port ranges and blocks the standard Entry IP	2.4

Web site supporting HTTP2, Perfect Forward Secrecy, Secure Renegotiation, TLS up to 1.3, DHE, ECDHE and HSTS. No external tracking applications or cookies from third parties.
airvpn.org web server configuration provides a balance between compatibility and security strength, with no dangerous compromise (A+ rating in Qualys SSL Labs).
airvpn.dev web server configuration provides a hardened security configuration to get a rating aiming to 100% (Qualys SSL Labs, CryptCheck) which sacrifices compatibility with older systems and browsers (example: Android 6 will not connect).

Website have a Web App Manifest ("Add to Home Screen" prompt).

Detailed information here.
securitytxt.org support, RFC5785 link