VPN safeguards traffic and provides online privacy, but it's not always possible to use a VPN. There are several ways in which VPN blocks are implemented by governments, ISPs and network administrators. VPN obfuscation is used to mask VPN traffic so that it isn't easily identified as a VPN traffic.
Many VPN users may have heard the term, VPN obfuscation but what is it? Obfuscation is a method used to hide VPN traffic so that VPN blocks cannot happen. VPN obfuscation is a disguise technique to make VPN traffic look like normal-unencrypted internet traffic. This is an attempt made by VPN providers to bypass VPN blocks, by making VPN traffic undetectable.
What is VPN obfuscation?
VPN obfuscation is a technique used to hide VPN traffic making it undetectable to firewalls or network detection services that tend to block VPN traffic. VPN obfuscation retains the VPN traffic but uses a technique to mask and hide recognizable VPN traffic patterns to disguise the system that detects it.
The traffic remains encrypted and cannot be manipulated. Obfuscation for VPN is usually associated with OpenVPN protocol, as this is the most used protocol and is easy to be detected. However, there are certain obfuscation methods that work over other VPN protocols as well.
VPN obfuscation is also referred to as Stealth VPN, Stealth mode or VPN cloaking.
Below are some reasons why VPN obfuscation is required:
- To bypass internet censorship and government restrictions
- Prevent ISP throttling of bandwidth
- Maintain anonymity and privacy
- Bypass VPN blocks applied by certain streaming services
- Enhance security while being connected to public network
- Bypass geographical VPN restrictions
Most VPN providers have the following categories of VPN servers:
- Standard VPN server – This is the most common VPN server that encrypts data and replaces IP to make traffic anonymous.
- Double VPN server – This provides dual encryption by sending traffic across two servers
- Dedicated IP server – Provides dedicated IPs for users based on the subscription plan. Owing to dedicated IPs, such VPN traffic is difficult to be blocked.
- Onion over VPN – Traffic flows via VPN and then over Onion network to maintain privacy
- P2P server – These are servers that are compatible with P2P network
- Obfuscated server – These are servers that can disguise VPN traffic and remain undetected to VPN blocks.
Obfuscated servers represent a set of servers that have been configured to use certain obfuscated technologies. Some VPN providers also use different names to represent such servers. An example of this is Chameleon protocol from VyprVPN or No Borders Mode from SurfShark.
How does VPN obfuscation work?
Some countries impose a VPN ban. Similarly, certain services such as streaming applications do not allow traffic from a VPN. As a workaround to bypass VPN blocks, obfuscation is implemented where the header information is modified.
The data packet is modified to look like any other ordinary internet traffic. This is a kind of camouflaged traffic though it originates from a VPN. The technique used is powerful enough to remain undetected even for DPI (Deep Packet Inspection).
Such traffic is assigned to port 443 which is also the port for HTTPs traffic. This makes such obfuscated traffic look like regular internet traffic, making it hard to be blocked. While this is the crux of VPN obfuscation, in reality, it requires a more complex implementation to bypass DPI based VPN blocks.
Different VPN obfuscation techniques
Most top-rated VPN providers offer obfuscated server support. This is based on proprietary technologies and while the names may be different but the underlying techniques are similar.
Some of the popular VPN obfuscation techniques are:
- OpenVPN Scramble – OpenVPN Scramble uses OpenVPN protocol combined with XOR cipher, which is a substitution-based algorithm. XOR in itself does not provide strong encryption and can be detected by DPI.
However, OpenVPN and XOR put together can provide good encryption. XOR is used by hackers to disguise malware and this is one of the reasons why XOR isn’t so popular.
OpenVPN along with XOR gives strong encryption along with obfuscation using XOR cipher. Network packet analyzers such as Wireshark cannot detect such OpenVPN traffic as OpenVPN but detect it as UDP.
This is not a full-proof obfuscation method and is not completely undetected by government VPN blocks. However, OpenVPN scramble makes it difficult to be detected for VPN blocks.
- Obfsproxy – Obfsproxy, which is a subproject of Tor offers obfuscation. This has obfs2 and obfs3 modules though obfs4 provides best obfuscation.
This uses pluggable transports to modify the traffic flow between client and server. Obfsproxy makes the VPN traffic look like normal HTTP traffic. This does not use any recognizable byte pattern. To use Obfsproxy along with OpenVPN, you would have to contact the VPN provider for the settings.
Obfsproxy is less secure and hence requires less bandwidth. This again is not completely undetectable and can be blocked using entropy test.
- OpenVPN over SSL/SSH – Wrapping OpenVPN on SSL, can make the traffic undetectable. The setup however requires some technical expertise and setting changes. This is usually done by using Stunnel.
OpenVPN on SSL might result in a drop in internet speed. Some VPN provider offer OpenVPN solutions tied with SSL.
Similar to SSL, SSH can also be used as an obfuscation technique. This again requires some technical expertise and you may have to contact your VPN provider. AirVPN offers OpenVPN over SSL as well as SSH.
- Shadowsocks – This is an open-source project that uses SOCKS5 proxy. Shadowsocks, mainly hides data, though it provides weak encryption. VPN providers use Shadowsocks with OpenVPN to provide obfuscation.
VPN obfuscation techniques result in hiding your traffic and bypassing VPN blocks. However, this does not guarantee to bypass all kinds of VPN blocks. To maximize the potential of obfuscation, one must search for high rated VPN services that offer VPN obfuscation.
With VPN obfuscation there is additional processing done on the network traffic and hence this will result in a dip in the internet speed. To get the best out of VPN obfuscation users can:
- Connect to the nearest VPN server. This will result in lesser time and hence the internet speed will not suffer.
- Explore a different VPN protocol which may be less susceptible to VPN blocks.
- Implement split tunneling wherein only some critical traffic flows via VPN, while other regular traffic will not use VPN.
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