PPTP vs L2Tp vs OpenVPN vs SSTP vs IKEv2

Every now and then I find myself googling some stuff to find the best answers for my questions sometimes I get to much of information and sometimes I get the most precise and very descriptive answers and today happens to be one of those days where I run in to a website called bestvpn.com and found a very descriptive comparison between different VPN Technologies and I thought you might want to know these things. Below you will find the article I found on their website.

PPTP

Point-to-Point Tunneling Protocol was developed by a consortium founded by Microsoft for creating VPN over dialup networks, and as such has long been the standard protocol for internal business VPN. It is a VPN protocol only, and relies on various authentication methods to provide security (with MS-CHAP v2 being the most common). Available as standard on just about every VPN capable platform and device, and thus being easy to set up without the need to install additional software, it remains a popular choice both for businesses and VPN providers. It also has the advantage of requiring a low computational overhead to implement (i.e. it’s quick).

However, although now usually only found using 128-bit encryption keys, in the years since it was first bundled with Windows 95 OSR2 back in 1999, a number of security vulnerabilities have come to light, the most serious of which is the possibility of unencapsulated MS-CHAP v2 Authentication. Using this exploit, PPTP has been cracked within 2 days, and although Microsoft has patched the flaw (through the use of Protect Extensible Authentication Protocol PEAP authentication), Microsoft issued a recommendation that VPN users should use L2TP/IPsec or SSTP instead.

Knowing that PPTP was insecure anyway, it came as no surprise to anybody that the NSA almost certainly decrypts PPTP encrypted communications as standard. Perhaps more worrying is that the NSA has (or is in the process of) almost certainly decrypted the vast amounts of older data it has stored, which was encrypted back when even security experts considered PPTP to be secure.

Pros

• Client built-in to just about all platforms

• Very easy to set up

• Fast

Cons

• Not at all secure (the vulnerable MS CHAPv2 authentication is still the most common in use)

• Definitely compromised by the NSA

L2TP and L2TP/IPsec

Layer 2 Tunnel Protocol is a VPN protocol that on its own does not provide any encryption or confidentiality to traffic that passes through it. For this reason it is usually implemented with the IPsec encryption suite (similar to a cipher, as discussed below) to provide security and privacy.

L2TP/IPsec is built-in to all modern operating systems and VPN capable devices, and is just as easy and quick to set up as PPTP (in fact it usually uses the same client). Problems can arise however, because the L2TP protocol uses UDP port 500, which is more easily blocked by NAT firewalls, and may therefore require advanced configuration (port forwarding) when used behind a firewall (this is unlike SSL which can use TCP port 443 to make it indistinguishable from normal HTTPS traffic).

IPsec encryption has no major known vulnerabilities, and if properly implemented may still be secure. However, Edward Snowden’s revelations have strongly hinted at the standard being compromised by the NSA, and as John Gilmore (security specialist and founding member of the Electronic Frontier Foundation) explains in this post, it is likely that it has been deliberately weakened during its design phase.

Relatively minor compared to the last point, but probably worth mentioning, is that because L2TP/IPsec encapsulates data twice, it is not as efficient as SSL based solutions (such as OpenVPN and SSTP,) and is therefore slightly slower.

Pros

• Usually considered very secure but see cons

• Easy to set up

• Available on all modern platforms Cons

Cons

• May be compromised by the NSA

• Likely deliberately weakened by the NSA

• Slower than OpenVPN

• Can struggle with restrictive firewalls

OpenVPN

OpenVPN is a fairly new open source technology that uses the OpenSSL library and Secure Socket Layer and Transport Layer Security SSLv3/TLSv1 protocols, along with an amalgam of other technologies, to provide a strong and reliable VPN solution. One of its major strengths is that it is highly configurable, and although it runs best on a UDP port, it can be set to run on any port, including TCP port 443. This makes traffic on it impossible to tell apart from traffic using standard HTTPS over SSL (as used by for example Gmail), and it is therefore extremely difficult to block.

Another advantage of OpenVPN is that the OpenSSL library used to provide encryption supports a number of cryptographic algorithms (e.g. AES, Blowfish, 3DES, CAST-128, Camellia and more), although VPN providers almost exclusively use either AES or Blowfish. 128-bit Blowfish is the default cipher built in to OpenVPN, and although it is generally considered secure, it does have known weaknesses, and even its creator was quoted in 2007 as saying ‘at this point, though, I’m amazed it’s still being used. If people ask, I recommend Twofish instead’.

AES is the newer technology, has no known weaknesses, and thanks to its adoption by the US government for use in protecting ‘secure’ data, is generally considered the ‘gold standard’ when it comes to encryption. The fact that it has a 128-bit block size rather than Blowfish’s 64-bit block size also means that it can handle larger (over 1 GB) files better than Blowfish. However, both ciphers are NIST certified, which while not widely recognized as problem, we have issues with. See below for a discussion about this.

How fast OpenVPN performs depends on the level of encryption employed, but it is generally faster than IPsec.

OpenVPN has become the default VPN connection type, and while natively supported by no platform, is widely supported on most through third party software (including both iOS and Android).

Compared to PPTP and L2TP/IPsec, OpenVPN can be a bit fiddly to set up. When using generic OpenVPN software in particular (such as the standard open source OpenVPN client for Windows), it is necessary to not only download and install the client, but also to download and setup additional configuration files. Many VPN providers get around this configuration problem by supplying customized VPN clients.

Perhaps most importantly in light of the information obtained from Edward Snowden, it seems OpenVPN has not been compromised or weakened by the NSA, and is also (thanks to its use of ephemeral key exchanges, as we will discuss later) immune to NSA attacks on RSA key encryption. Although no-one knows the full capabilities of the NSA for sure, both the evidence and the mathematics strongly point to OpenVPN, if used in conjunction with a strong cipher, being the only VPN protocol that can be considered truly secure.

Pros

• Highly configurable

• Very secure (probably even against the NSA)

• Can bypass firewalls

• Can use a wide range of encryption algorithms

• Open source (and can therefore be readily vetted for back doors and other NSA style tampering)

Cons

• Needs third party software

• Can be fiddly to set up

• Support on mobile devices is improving, but is not as good as on the desktop

SSTP

Secure Socket Tunneling Protocol was introduced by Microsoft in Windows Vista SP1, and although it is now available for Linux, RouterOS and SEIL, it is still largely a Windows-only platform (and there is a snowball’s chance in hell of it ever appearing on an Apple device!). SSTP uses SSL v3, and therefore offers similar advantages to OpenVPN (such as the ability to use to TCP port 443 to avoid NAT firewall issues), and because it is integrated into Windows may be easier to use and more stable.

However unlike OpenVPN, SSTP is a proprietary standard owned by Microsoft. This means that the code is not open to public scrutiny, and Microsoft’s history of co-operating with the NSA, and on-going speculation about possible backdoors built-in to the Windows operating system, do not inspire us with confidence in the standard.

Pros

• Very secure (depends on cipher, but usually very strong AES)

• Completely integrated into Windows (Windows Vista SP1, Windows 7, Windows 8)

• Microsoft support

• Can bypass most firewalls

Cons

• Only really works in a Windows only environment

• Proprietary standard owned by Microsoft so cannot be independently audited for back doors and suchlike

IKEv2

Internet Key Exchange (version 2) is an IPSec based tunneling protocol that was jointly developed by Microsoft and Cisco, and which is baked into Windows versions 7 and above. The standard is supported by Blackberry devices, and independently developed (and compatible) open source implementations are available for Linux and other operating systems. As always, we are wary of anything developed by Microsoft, but if open source versions are used then there should be no problem.

Dubbed VPN Connect by Microsoft, IKEv2 is particularly good at automatically re-establishing a VPN connection when users temporarily lose their internet connections (such as when entering or leaving a train tunnel).

Mobile users in particular, therefore, benefit the most from using IKEv2, which because of its support for the Mobility and Multihoming (MOBIKE) protocol, also makes it highly resilient to changing networks. This is great news for cell phone users who, for example, connect their smart phones to a WiFi network while at home but switch to mobile data use when out and about, or who regularly switch between hotspots.

IKEv2 is even more useful to Blackberry users, as it is one of the few VPN protocols supported by Blackberry devices.

It is not as ubiquitous as IPSec (i.e. it is supported on much fewer platforms), but IKEv2 is considered at least as good as, if not superior to, L2TP/IPsec in terms of security, performance (speed), and stability.

Pros

• Faster than PPTP, SSTP and L2TP, as it does not involve the overhead associated with Point-to-Point protocols (PPP)

• Very stable – especially when switching network or reconnecting after a lost internet connection

• Very secure – supports AES 128, AES 192, AES 256 and 3DES ciphers

• Easy to setup (at least at the user-end!)

• Protocol is supported on Blackberry devices

Cons

• Not supported on many platforms

• Uses the same UDP port 500 as IPSec (and PPTP), which is easier to block than SSL based solutions such as OpenVPN or SSTP

• Implementing IKEv2 at the server-end is tricky, which is something that could potentially result in issues developing

• We only trust open source implementations