What should I ask my VPN provider before buying?

[Teacher]

Hello! Choosing a VPN service may cause some problems. You may not trust your Internet service provider to protect your privacy (and, as the US FTC recently concluded, you really shouldn't). Perhaps you don't trust your government. You may not even trust all governments and corporations. Be that as it may, if you are by nature a fan of exploring things before you start using them, this guide will be helpful.

If you are particularly concerned about privacy, you probably want to avoid making your research about VPN providers public. Although many people use VPNs, deep research can give you away as someone who has something to hide. You can reduce this risk by using free VPNs (such as Calyx VPN) and webmail (such as VFEmail) at this stage. For even more privacy, you can use the implementation of VFEmail on the Tor network.

There is relatively little reliable and trustworthy information about VPN services on the Internet. We recommend that you ignore sites with the headings "best VPNs" and "VPN reviews". Most of them contain paid reviews, and some simply post bad reviews about VPN services that refuse to buy favorable reviews. Even honest sites, as a rule, just make lists of popular services, without thinking about the quality. If you ever need to get information from a dedicated VPN review source, look for those that don't use affiliate programs in outbound links (referrals).

When searching, it is important to choose VPN providers that will help you meet your specific privacy goals. We recommend that you carefully study the providers ' websites and carefully read their terms of service and privacy policy. Look for clear and unambiguous language and be suspicious of the legal template.

For example, if you plan to share copyrighted media files via BitTorrent, it's best to avoid providers that explicitly prohibit such use. If the availability of multiple locations is important to you, choose accordingly, but keep in mind the contradiction between diversity and security. It is more likely that providers with multiple IP addresses in different countries use virtual private servers instead of physical dedicated ones.

How potential VPN providers respond to your questions can be as informative as the answers themselves. You need fast, complete, clear and accurate answers. Unclear or incorrect answers to technical questions indicate dishonesty and / or incompetence. Late responses do not bode well for future customer support.

Below are some questions that you can ask your VPN provider before purchasing, as well as expected answers and explanations. For technical questions, the OpenVPN guide and How-to, as well as the official WireGuard page, are useful resources.

Questions​

1. Is there a monthly bandwidth usage limit?
2. Do you limit connections that exceed the bandwidth limits?
3. How many simultaneous connections are allowed for a single account?
4. How many hops are there in your VPN connections?
5. What type (s) of VPN encryption do you use? Why?
6. Do you support perfect forward secrecy? If so, how?
7. Do you provide users with DH key files?
8. How do you authenticate clients-certificates and keys, or usernames and passwords?
9. Do you use HMAC-based TLS authentication? If so, why?
10. Do you ever send usernames and passwords to clients via email?
11. Does each client have a unique client certificate and key?
12. Where are your VPN gateway servers hosted-on a hosting service, in one place, or within the company?
13. Do any of your VPN gateway servers run on VPS or cloud servers?
14. How are your servers protected?
15. Where is the user's account information stored?
16. How is communication between servers secured?
17. Is port forwarding allowed by users?
18. Are all client ports forwarded by default? If so, on which servers?

Answers​

1. Is there a monthly bandwidth usage limit? This restriction has become less common in recent years, but some providers use it at free tiers so that potential customers can try out their services before switching to a paid data plan. Usage restrictions for paid subscriptions are more common for VPN resellers, so it's best to avoid providers that impose them.
2. Do you limit connections that exceed the bandwidth limits? The best answer depends on your goals. It's only natural to want the fastest possible connection. However, if you have a very fast connection to your ISP, you can transmit much more traffic than any other user using your VPN outlet. This reduces your anonymity.
3. How many simultaneous connections are allowed for a single account? Using a VPN with a large number of addresses, it is sometimes convenient to work under several aliases at the same time. You may also want to connect from multiple devices at the same time. However, it also encourages misuse of account sharing, which can overload VPN servers and slow down your connection.
4. How many hops are there in your VPN connections? Most VPN services offer only a single hop connection. That is, you connect to a VPN gateway server and your traffic goes out to the Internet from the same server, or possibly from another server on the same local network. With a single-hop connection, it is easy for attackers to register incoming and outgoing traffic.
5. What type (s) of VPN encryption do you use? Why? OpenVPN can operate in two different modes. In one of them, authentication and encryption are performed using a shared static key. Although this mode is very easy to set up, compromising the key allows an attacker to decrypt all previous traffic. No self-respecting provider uses this method. However, if you only received one key file from your provider, open it in a text editor and look at the last line. If it includes 'CERTIFICATE', then everything is fine. But if it contains a 'KEY', ask for a refund. Another OpenVPN mode uses SSL/TLS as the control channel and encrypts the data channel with periodically changing static keys. If an attacker manages to compromise one of these data channel keys, they will only be able to decrypt this traffic, but not any past or future traffic. In other words, "Perfect Forward Secrecy" is configured. By default, OpenVPN uses 1024-bit RSA for certificates that authenticate SSL/TLS control channel handshakes, and BF-CBC (128-bit) as the data channel cipher. This is probably sufficient in most cases. However, it can be argued that providers using 2048-bit RSA and AES-256-CBC (256-bit) are generally more security-conscious. Both BF-CBC and AES-256-CBC operate in Cipher Block Chaining (CBC) mode. If your provider uses something else (CFB, OFB, etc.), they are either incompetent or have very good reasons for doing so. Figure them out. Recently introduced to the market, the WireGuard VPN protocol has gained rapid adoption among VPN providers. This protocol was not designed with commercial VPN services and their privacy concerns in mind. Capable providers should demonstrate that they have solutions to the following problems: 1. Public IP addresses of peers are stored in memory (for example, adding key management that deletes/restores the configuration) 2. Allocation/rotation of tunnel IP addresses (for example, using callbacks that generate new IP addresses that are distributed between all servers) 3. Lack of perfect forward secrecy (for example, using automatic key pair regeneration at regular intervals).
6. Do you support perfect forward secrecy? If so, how? Any provider that uses OpenVPN in SSL / TLS mode provides perfect forward secrecy. Additional hand-waving that goes beyond these limits should make you suspicious. As noted earlier, the implementation of WireGuard requires special measures to support forward secrecy.
7. Do you provide users with Diffie Hellman key files? This is a trick question. It is true that OpenVPN uses static Diffie Hellman key files to ensure perfect forward secrecy. But this static Diffie Hellman key file ('dh1024.pem' or 'dh2048. pem') is only needed on the server. Any provider that provides them to users is incompetent.
8. How do you authenticate clients-certificates/keys or usernames/passwords? In SSL/TLS mode, OpenVPN clients authenticate servers by checking whether the server has a certificate signed by the certificate authority ('a.crt') that the provider provided them with. OpenVPN supports two methods of client authentication by servers. One of them is based on certificates and keys (such as 'client.crt' and 'client. key'). The other relies on usernames and passwords (via auth-user-pass). Servers can use both, but this is already bordering on excessive. For p2p connections where full network access is at stake, it is very important that servers authenticate clients using certificates and keys. For VPN services, this is not a problem, since clients simply see the Internet. In addition, for VPN services, providing each client with a unique certificate is a privacy risk.
9. Do you use HMAC-based TLS authentication? If so, why? When TLS authentication is enabled (via tls-auth), servers ignore SSL/TLS handshake packets from clients that do not have a valid HMAC signature. This feature protects VPN servers from DoS attacks, port scanning, and other attacks. If this feature is implemented, providers can provide a key (usually 'ta. key') or it can be negotiated on the fly. This is partly a trick question. Any provider claiming that this is necessary for perfect forward secrecy is either dishonest or incompetent.
10. Do you ever send usernames and passwords to clients via email? This is a dangerous practice, and especially for the provider. Detractors who compromised usernames and passwords during delivery can gain free access or even block paying users by changing their passwords. There is also a risk that attackers may involve users in criminal activities. Even so, if you successfully change your password immediately after receiving it, you are safe. If you can't log in to change your password, complain and request a new account. For providers that are otherwise attractive, this is not a fatal error.
11. Does each client have a unique client certificate and key? This is another trick question. As an answer to this question, you can provide the same client certificate for all clients, or not provide it at all and rely on the username and password for authentication. It may seem like a good idea that each user should have their own certificate and key. And this is true in the context of an enterprise. But for VPN services, this is very dangerous, as it can potentially link user accounts to the recorded traffic. Some providers explain that they issue unique client certificates to make it easier to neutralize malicious clients. However, this is just as easy to do with usernames, and usernames are more easily invalidated than certificates. If this is a key question for you, you can easily check it out by purchasing two short-term subscriptions, paying with bitcoins via Tor, and using temporary email addresses with anonbox, etc.
12. Where are your VPN gateway servers hosted-on a hosting service, in one place, or within the company? This is also partly a trick question. We would be very suspicious of any VPN provider that claims that its servers are managed in-house. You may ask how they cover the cost of maintaining facilities with high-speed lines in several countries. The most plausible answer is that they build their own backend servers and send them to shared hosting locations. Earn extra points for protecting your servers. Typical physical protection measures include embedding RAM in hot melt glue, as well as disabling USB ports. The most likely acceptable answer is to use dedicated servers. Earn extra points for server security measures such as using full-disk encryption and storing short-term logs in RAM (tempfs).
13. Do any of your VPN gateway servers run on VPS or cloud servers? Providers should never host VPN gateway servers on Virtual private servers (VPS) or cloud servers. As virtual machines, they are fully controlled by the host operating system, and all actions and data are easily accessible through the host. Providers should always use dedicated physical servers that are properly protected from unauthorized access.
14. How are your servers protected? VPN services typically use servers that play three roles. There are gateway servers that establish VPN connections to clients, as well as route client traffic to the Internet. With a single hop connection, all these functions can be performed by a single server. There are servers that host the service's website. There are also servers that manage user account information and provide authentication services to gateway servers and web servers. All client traffic is routed through gateway servers. If these servers are not properly protected, attackers can compromise them and thereby violate users ' privacy by logging their traffic. VPN gateways must be strengthened in accordance with industry standards, for example: CIS benchmarks or NSA core recommendations. Most importantly, VPN gateway servers should not work with other network services, such as website hosting or user accounting and authentication. This significantly increases the risks. You can use a port scanner, such as nmap, to check which ports and services are available on the VPN gateway. However, keep in mind that many providers open VPN servers on non-standard ports such as 80 (HTTP) and 443 (HTTPS) to bypass firewall blocking.
15. Where is the user's account information stored? Ideally, vendors should store this information on their own servers, which are appropriately encrypted and protected from detractors. In addition, they should separate authentication data that should be available to the gateway servers from credentials that may include private user information, such as logs, email addresses, and payment records.
16. How is communication between servers secured? Well-designed VPNs include networks of specialized servers with various functions that communicate securely with each other. For example, gateway servers must communicate with authentication servers to verify that users are authorized to connect. There are also internal provisioning systems that use sales data from websites to create and update user accounts, and then update authentication servers. Given the sensitivity of this data and its value to attackers, all communications between these servers must be securely encrypted. Most often, OpenVPN or IPsec persistent tunnels between servers are used for this purpose.
17. Is port forwarding allowed by users? When you are connected to a VPN, the gateway server protects your device from potentially hostile incoming connections in the same way that a router or firewall on a local network does. However, allowing incoming connections on certain ports is necessary for servers to operate or for participating in p2p networks where your node must be visible to other nodes. This process is called port forwarding. When port forwarding is enabled, your device directly accesses the Internet through the forwarded ports, without any protection from the VPN service. An attacker can successfully exploit a vulnerability in a service that listens on a forwarded port and compromise your device. In addition to the typical consequences, such as participation in a botnet and data theft, an adversary can violate your privacy and anonymity.
18. Are all client ports forwarded by default? If so, on which servers? Some VPN services forward all client ports by default. Some do this only on certain servers. In some services, port forwarding on different servers varies without any scheme or documentation. While this can be verified by port scanning, the problem is that different clients using the same exit IP address may have the same ports forwarded.