Public wireless access points are seductively dangerous. Sitting in the sun sipping a Pimms or cappuccino, you can browse, barter and banter. However, if you can hook up so simply, it's only too easy to eavesdrop or intrude. Steganos Internet Anonym VPN (SIAVPN) is intended to protect your privacy, whether you're surfing at a café or mail-bashing at your desktop.
Its strategy isn't unique, being essentially the same as that available in the freeware application Tor (tor.eff.org): instead of passing Internet traffic through to your ISP in the normal way, it encrypts it and sends it over a VPN connection to a third-party server, where it's decrypted and launched onto the Internet. This makes it impossible to monitor or intercept packets between your Mac and the remote server, and your true IP address isn't revealed. Steganos employs many different anonymising servers, those used during testing being located in various parts of Germany.
Accomplishing this special VPN requires components that go close to the kernel of Mac OS X. There are three key ingredients installed: a pair of kernel extensions (.kext), matching startup items and the SIAVPN application itself. The paired extensions and their startup items are the cross-platform Tap and Tun networking proxies that virtualise networking and support VPN tunnelling using OpenVPN and SSL.
This initial release for OS X (version 1.1.3) has a slightly fussy interface. Although Tap and Tun start up automatically, you have to run the SIAVPN application and manually connect before your Mac becomes cloaked. Inevitably, there's a modest overhead reflected in net throughput: while ping latency remains essentially unchanged, allowing for geographical location of the anonymised portal, an example download dropped from 1922 to 1753bits/sec (9%), and upload from 690 to 667 (3%). The Tap/Tun approach ensures almost all Internet traffic is routed via VPN to Steganos' servers, while local network traffic remains unaffected.
This anonymisation is, however, limited. Remote recognition that relies on browser characteristics are, of course, unaffected. Some websites and online services require recognition of your IP address, in which case, SIAVPN enables you to put their details in an exclusion list, and will talk in plain directly to them. The greatest concern with SIAVPN is its Tap/Tun foundation.
During testing, Safari 3 beta was installed and temporarily took an intense dislike to Tap/Tun; be prepared to encounter similar transient or more persistent incompatibilities. Steganos' service is paid for by subscription: you have a choice of modest cost capped at 25GB per month or an unlimited capacity for a much heftier subscription.
However, the most worrisome issue is the trust you're putting in Steganos and its servers. SIAVPN may make a lot of sense if you have no cheaper VPN to use and don't fancy Tor. In other circumstances, you're saying you trust Steganos to protect your privacy better than your own ISP. That may be so, but where's the evidence?
Needs Mac OS X + Internet accessAuthor: Howard Oakley
Steganos Internet Anonym VPN