Internet connections using the OpenVPN protocol can be easily identified by using DPI (Deep Packet Inspection) technologies and blocked with minor collateral damage.
This result was presented in a technical paper published earlier this month by a team of researchers in the United States. The team performed a large-scale study involving a million users, demonstrating that it was possible to identify 85% of the existing OpenVPN traffic while having negligible false positives.
OpenVPN is a versatile and widely used VPN (Virtual Private Network) protocol released in 2001 as an open-source project. It offers strong encryption, a variety of authentication methods, and superior cross-platform compatibility. While its speeds are not up to par with more modern protocols like WireGuard, it remains a solid option available in most modern VPN software. See our guide on VPN protocols for an in-depth comparison.
The study unveils that despite OpenVPN’s popularity for its robust security features, it’s not immune to detection and blocking by governments and ISPs (Internet Service Providers).
The research team first identified OpenVPN connections using three fingerprints based on protocol features like byte patterns, packet sizes, and server responses. They then employed a strategic two-phase attack, starting with passive fingerprinting to spot potential OpenVPN flows. This was followed by active probing, confirming the VPN’s presence by eliciting protocol-specific server responses.
Collaborating with Merit, a regional ISP that provided secured access to the traffic data of one million users, the researchers set their framework into motion, finding that they could pinpoint OpenVPN connections with an accuracy of 85%.
The study’s findings should be a wake-up call for both commercial VPN providers and VPN users, especially those in regions with stringent censorship, such as when using a VPN in China with the “Great Firewall” blocking many users. It is clear that the current obfuscation mechanisms and fingerprinting countermeasures used in the industry could be upgraded, particularly if they are being consistently blocked in Regions such as China and Russia. That said, we still see some VPNs working in these regions and bypassing censorship efforts.
The published technical paper proposes various short-term defenses, such as varying packet sizes and introducing noise in the data traffic to complicate fingerprinting efforts. However, the ultimate solution lies in the evolution of VPN protocols themselves, as the ever-advancing DPI technologies make the situation very challenging for older aging like OpenVPN.
Last summer, Russia started experimenting with protocol-based blocks in the country, targeting OpenVPN in Moscow and IKEv2 and WireGuard in other regions. This shows that ISPs can potentially identify VPN traffic if they fine-tune their methods against specific protocols, and unfortunately for OpenVPN, independent research has confirmed it.
We evaluate our framework in partnership with a million-user ISP and find that we identify over 85% of OpenVPN flows with only negligible false positives, suggesting that OpenVPN-based services can be effectively blocked with little collateral damage.
As the paper illustrates, OpenVPN is susceptible to quite accurate fingerprinting via a two-stage process: passive traffic analysis (Filter), followed by active probing (Prober). It reports >85% success rate in identifying OpenVPN connections.
Some networks may try to block VPN connections by blocking common connection ports used by VPN protocols. For example, OpenVPN uses TCP Port 1194 by default and blocking these ports will prevent a VPN from connecting to a server.
We are a Zero-Log service provider and Do Not keep records of your traffic, browsing, or activity while using our services. We do analyze website functionality for performance for purposes of improving our service offerings to our customers.
OpenVPN normally or you can say by default runs on port 1194. Changing the port to 443 helps most of the time. This method of changing the default port to 443 can be performed from the client side itself and this is the simplest workaround so far to conceal your VPN traffic.
Yes, your ISP can see your VPN server's IP address. But it can't see anything else. This means that your ISP can likely tell that you're using a VPN, but it cannot track your online activity, see the pages you visit, the files you download, or anything else you do on the internet.
You can often bypass a VPN block by switching servers or going to a different VPN provider. The organization blocking your access may have focused on only the more popular VPNs when choosing what to block, so you may be able to gain access using a less popular service.
Test multiple server locations: Connect to different server locations offered by your VPN provider. If you can bypass restricted websites, then your VPN is working.
You can't use a VPN while watching Netflix if you have an ad-supported plan. Go to your Account page to check your current plan. If you have an ad-supported plan: You'll need to change to an ad-free plan to use a VPN while watching Netflix.
Can police track online purchases made with a VPN? There is no way to track live, encrypted VPN traffic. That's why police or government agencies who need information about websites you visited have to contact your internet service provider (ISP for short), and only then your VPN provider.
The VPN encrypts your internet traffic before it leaves your computer. The encrypted traffic passes through your router and ISP, but because it's encrypted, neither of them can see its content.
No.Your data is encrypted, so your ISP can't see its contents. This includes DNS requests, which are sent through the VPN tunnel and resolved by the VPN provider. Your ISP can see the IP address of the VPN server you're connected to, but it can't see any connections made after that.
Through in-depth analysis of network traffic, the unique traffic characteristics of OpenVPN can be identified. Such as specific port numbers, encryption algorithms, and protocol flags. These characteristics provide a strong basis for the identification of OpenVPN.
Pushing the redirect-gateway option to clients will cause all IP network traffic originating on client machines to pass through the OpenVPN server. The server will need to be configured to deal with this traffic somehow, such as by NATing it to the internet, or routing it through the server site's HTTP proxy.
Yes, the point of OpenVPN is that the traffic is encrypted (unless you disable all security in the server's config file) between the client (your Windows laptop) and the Ubuntu Server. Your traffic to the internet is not encrypted though. You'd best use Tor if you want to hide your IP Address online.
Yes… if you're using a trusted VPN. Your ISP can't see what you're browsing online when you connect to a VPN. However, by detecting the encrypted data from your device, the ISP is aware that you're using a VPN. However, the ISP will not know your actual IP address or your browsing history.
VPNs encrypt all internet traffic before they leave your device, so even if someone intercepts traffic that contains PII, they won't be able to see the actual data.
Introduction: My name is Arline Emard IV, I am a cheerful, gorgeous, colorful, joyous, excited, super, inquisitive person who loves writing and wants to share my knowledge and understanding with you.
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