Millions of websites and billions of people rely on SSL to protect the transmission of sensitive information such as passwords, credit card details, and personal information with the expectation that encryption guarantees privacy. However, recently leaked documents appear to reveal that the NSA, the United States National Security Agency, logs very high volumes of internet traffic and retains captured encrypted communication for later cryptanalysis. The United States is far from the only government wishing to monitor encrypted internet traffic: Saudi Arabia has asked for help decrypting SSL traffic, China has been accused of performing a MITM attack against SSL-only GitHub, and Iran has been reported to be engaged in deep packet inspection and more, to name but a few.
The reason that governments might consider going to great lengths to log and store high volumes of encrypted traffic is that if the SSL private key to the encrypted traffic later becomes available — perhaps through court order, social engineering, successful attack against the website, or through cryptanalysis — all of the affected site’s historical traffic may then be decrypted at once. This really would open Pandora’s Box, as on a busy site a single key would decrypt all of the past encrypted traffic for millions of people.
There is a defence against this, known as perfect forward secrecy (PFS). When PFS is used, the compromise of an SSL site's private key does not necessarily reveal the secrets of past private communication; connections to SSL sites which use PFS have a per-session key which is not revealed if the long-term private key is compromised. The security of PFS depends on both parties discarding the shared secret after the transaction is complete (or after a reasonable period to allow for session resumption).
Eavesdroppers wishing to decrypt past communication which has used PFS face a daunting task: each previous session needs to be attacked independently. Even knowing the long-term private key does not help as the session key is not available by simple decryption. Conversely, when SSL connections do not use PFS, the secret key used to encrypt the rest of the session is generated by the SSL site and sent encrypted with the long-term private-public key pair. If this long-term private key is ever compromised all previous encrypted sessions are easily decrypted.
Perfect forward secrecy was invented in 1992, pre-dating the SSL protocol by two years, and consequently one might reasonably have expected that SSL would have made operational use of PFS from the outset. Nevertheless, almost twenty years later, PFS usage is not used by the majority of SSL sites.
The use of PFS is dependent on the negotiation between the browser and the web site successfully agreeing on a PFS cipher suite. One might reasonably expect browsers to do all they can to support PFS cipher suites as PFS confers an advantage in privacy for the browser’s user community, and any PFS performance disadvantages may only be a serious issue at the larger scales found on the server-side. On the other hand, there are only a small number of browsers in widespread use, and if a government wished to maximise its influence in restricting the use of PFS in order to facilitate decryption of recorded encrypted transactions it would start with the web browsers.
Browser support for PFS
Netcraft has tested the cipher suite selection of five major browsers — Internet Explorer, Google Chrome, Firefox, Safari and Opera — against 2.4 Million SSL sites from Netcraft's June SSL Survey. The support for PFS varied significantly between browsers: only a tiny fraction of Internet Explorer's SSL connections operated with PFS; whereas Google Chrome, Opera and Firefox were protected for approximately one third of connections. Safari fared only a little better than Internet Explorer.
The actual cipher suites used when connecting to 2.4 Million SSL sites with the cipher suite settings extracted from each browser. *Opera does not include its TLS 1.2 cipher suites.
Internet Explorer does particularly poorly as it does not support any cipher suite that uses both RSA public keys and non-elliptic-curve DH key exchange, which includes the most popular PFS cipher suite. The PFS cipher suites that IE does support have a lower priority than some of the most commonly supported non-PFS cipher suites. Curiously, IE does support DHE-DSS-AES256-SHA, which uses the rarer DSS authentication method, but not the very popular DHE-RSA-AES256-SHA.
Browser priority Cipher Suite Real-world usage in SSL Survey 1 AES128-SHA 63.52% 2 AES256-SHA 2.21% 3 RC4-SHA 17.12% 4 DES-CBC3-SHA 0.41% 5 ECDHE-RSA-AES128-SHA 0.08% 6 ECDHE-RSA-AES256-SHA 0.21% 7 ECDHE-ECDSA-AES128-SHA 0.00% 8 ECDHE-ECDSA-AES256-SHA 0.00% 9 DHE-DSS-AES128-SHA 0.00% 10 DHE-DSS-AES256-SHA 0.00% 11 EDH-DSS-DES-CBC3-SHA 0.00% 12 RC4-MD5 16.46%
Internet Explorer 10's cipher suite ordering and the actual negotiated cipher suite in Netcraft's SSL survey. PFS cipher suites are highlighted in bold and green.
Safari supports many PFS cipher suites but non-elliptic-curve cipher suites are used only as a last resort. As several non-PFS ciphers have a higher priority, web servers respecting the browser's preferences will end up selecting a non-PFS cipher suite even if the web server itself does support some (non elliptic-curve) PFS cipher suites.
Chrome, Firefox, and Opera all do better, preferring PFS cipher suites ahead of non-PFS at any given strength level — for example Opera's preference list starts: DHE-RSA-AES256-SHA, DHE-DSS-AES256-SHA, AES256-SHA, DHE-RSA-AES128-SHA, DHE-DSS-AES128-SHA, AES128-SHA. Netcraft did not include any cipher suites only present in TLS 1.2 which includes many of Opera's PFS cipher suites, so the results for Opera form a lower bound on the number of SSL sites using PFS with Opera.
None of the browsers change their user interface perceptibly to reflect the presence of PFS akin to the way EV certificates are treated to a green address bar. Google Chrome and Opera show the cipher suite used (in popups or dialog boxes), but they rely on a user understanding the implications of wording such as "[..] ECDHE_RSA as the key exchange mechanism".
Web server support for PFS
Despite a browser's best efforts to prefer PFS cipher suites, the key exchange method used is selected by the server and it may either not support any PFS cipher suites or it may prefer to use an alternative cipher suite (and perhaps reasonably so for performance reasons). The use of the Diffie-Hellman key exchange does impose a performance penalty as there is additional computation required to derive the secret key.
Using any browser's cipher suite preference order, at least two-thirds of the SSL connections made in the Netcraft SSL survey did not use a cipher suite with PFS at all.
Connections to 2.4 Million SSL sites in the SSL survey, once for each browser, split by the web server vendor
nginx, an open-source web server originally written by Russian Igor Sysoev, uses strong cipher suites by default, which has caused some to comment on nginx's SSL performance. With the exception of Internet Explorer and Safari, more than 70% of SSL sites using the web server selected a PFS cipher suite when visited with a modern browser.
The usage of PFS amongst SSL sites using Apache is also fair, around two-thirds of the SSL sites it serves use a PFS cipher suite when visited in Firefox, Chrome, or Opera. Conversely, Microsoft's support for PFS cipher suites is notably lacking; both Microsoft IIS and Internet Explorer only rarely use PFS cipher suites — when used together only 111 (0.01%) of SSL connections between IIS and IE used PFS.
How is this related to PRISM?
Website Internet Explorer Google Chrome Firefox Safari Opera www.facebook.com RC4-SHA RC4-SHA RC4-SHA RC4-SHA RC4-SHA www.twitter.com RC4-SHA RC4-SHA RC4-SHA RC4-SHA RC4-SHA www.yahoo.com AES128-SHA CAMELLIA256-SHA CAMELLIA256-SHA AES128-SHA AES256-SHA www.google.com ECDHE-RSA-AES128-SHA ECDHE-RSA-RC4-SHA ECDHE-RSA-RC4-SHA ECDHE-RSA-RC4-SHA RC4-SHA login.live.com AES128-SHA AES128-SHA AES128-SHA AES128-SHA AES128-SHA www.aol.com RC4-SHA RC4-SHA RC4-SHA RC4-SHA RC4-SHA www.apple.com AES256-SHA AES256-SHA AES256-SHA AES256-SHA AES256-SHA commerce.paltalk.com RC4-SHA RC4-SHA RC4-SHA RC4-SHA RC4-SHA
The negotiated cipher suite for a selection of SSL sites belonging to companies implicated in the PRISM programme. PFS cipher suites are highlighted in bold and green.
Many SSL sites of those companies implicated in the PRISM programme do not use PFS cipher suites when visited in any of the major browsers. Google, however, does use a PFS cipher suite in most browsers, with the notable exception of Opera. If PRISM operates by examining SSL traffic, which has been said to be fairly unlikely given its quoted $20M cost, all of the traffic to these SSL sites (except for Google) could have been compromised if the NSA had access to the private key.
Some other noteworthy SSL sites
Website Internet Explorer Google Chrome Firefox Safari Opera www.cloudflare.com ECDHE-RSA-AES128-SHA ECDHE-RSA-RC4-SHA ECDHE-RSA-RC4-SHA ECDHE-RSA-RC4-SHA RC4-SHA www.duckduckgo.com RC4-SHA RC4-SHA RC4-SHA RC4-SHA RC4-SHA www.mega.co.nz RC4-SHA RC4-SHA RC4-SHA RC4-SHA RC4-SHA
The negotiated cipher suite for a selection of SSL sites. PFS cipher suites are highlighted in bold and green.
CloudFlare has taken a similar approach to Google using ECDHE RC4 or AES cipher suites, but also leave Opera users without the protection of PFS. One of CloudFlare's options for SSL deployment is 'flexible' SSL which encrypts traffic from the browser to CloudFlare but if the content is not returned from its cache, the connection from CloudFlare to the original website is made without SSL. Rather than attempting to decrypt the encrypted content it may be easier to intercept unencrypted traffic between CloudFlare and the original website.
Mega does not use PFS cipher suites, perhaps a risky move given the history of raids on Megaupload's servers by the US Government. With physical access to the servers, it is not implausible that the private keys of any server could be extracted, even if it is from non-persistent memory.
Conspiracy theorists may be unsurprised that:
- Microsoft’s support for PFS is conspicuous by its absence across Internet Explorer, IIS, and some of its own web sites. Apple’s support for PFS in Safari is only slightly better.
- Russia, long-time target of US spies, is the home of the developer of nginx, the web server which uses PFS most often.
- Almost all of the websites run by companies involved in the PRISM programme do not use PFS.
Whilst conspiracy theorists may delight in speculating on the reasons why PFS isn't ubiquitous, one reason may be web sites' (bona fide) performance concerns: Mavrogiannopoulos reports up to a 3x performance penalty starting an SSL connection using DHE-RSA instead of plain RSA. The lack of clear in-browser notifications of the use of PFS cipher suites may persuade popular SSL sites to forgo the protection PFS offers, which typical users do not notice, to instead improve the web site's performance, which typical users do notice.
Without the support of two major browsers and major websites most internet users are missing out on the security benefits of perfect forward secrecy. Without the protection of PFS, if an organisation were ever compelled — legally or otherwise — to turn over RSA private keys, all past communication over SSL is at risk. Perfect forward secrecy is no panacea, however; whilst it makes wholesale decryption of past SSL connections difficult, it does not protect against targeted attack on individual sessions. Whether or not PFS is used, SSL remains an important tool for web sites to use to secure data transmission across the internet to protect against (perhaps all but the most well-equipped) eavesdroppers.
It should be noted that the US Government, along with many others governments, can issue any SSL certificate of its choosing — albeit at the risk of breaking the rules of the programme and at the risk of detection by alert users and by Google (for certain SSL sites). The scale at which an active attack is practical and unlikely to be detected, however, would be significantly smaller than that of a passive eavesdropper exploiting the lack of PFS.
More detail on PFS negotiation
The cipher suite selected for the SSL connection depends on an agreement between the browser and the SSL site. Both browsers and SSL sites can each have independent preference lists for SSL cipher suites. During the handshake the browser sends a ClientHello message which contains an ordered list of all supported cipher suites in preference order. The SSL site can either select the first cipher on that list which it also supports or it can use override the clients preference list with its own. As illustrated in the above diagram, either Cipher A (if the browser's preference order is respected) or Cipher C (if the website's preference order is respected) is used for the connection depending on the settings of the SSL site.
Illustration of cipher suite selection algorithms.
Diffie-Hellman key exchange (DH) and variants of it are used to negotiate a per-session shared secret key between two parties without ever transmitting the key itself. The per-session key can be discarded after the session has terminated (and after a suitable time period for renegotiation) leading to the ephemeral property which PFS relies upon. The security of Diffie-Hellman relies on the difficulty of the discrete logarithm problem to exchange DH public keys whilst making it difficult for an eavesdropper to determine the resulting shared secret. SSL cipher suites support both conventional ephemeral Diffie-Hellman key exchange (often referred to as EDH or DHE) and ephemeral elliptic curve Diffie-Hellman (ECDHE) which uses a similar scheme but relies on the difficulty of the elliptic curve Discrete Logarithm problem. Elliptic curve-based DHE key exchange despite being faster is supported by fewer SSL sites than conventional DHE.
[November 2013: Click to view updated graphs and statistics for DigitalOcean]
Cloud hosting startup DigitalOcean has grown extraordinarily over the past six months. In December 2012, DigitalOcean had just over 100 web-facing computers; in June 2013, Netcraft found more than 7,000. DigitalOcean provides SSD-backed virtual computers which are available by the hour. The cheapest droplet, as it refers to virtual computers, costs less than a cent per hour, about a third of the price of Amazon's cheapest option. DigitalOcean claims to be able to provision a new droplet within 55 seconds in one of three locations: New York, Amsterdam (available since January 2012), and San Francisco (April 2013).
Hosting provider December 2012 June 2013 Growth Growth (%) Amazon 134,117 165,438 +31,321 +23.35% Alibaba 6,649 17,347 +10,699 +160.91% Hetzner 75,880 84,896 +9,016 +11.88% DigitalOcean 138 7,134 +6,996 +5084.64% OVH 90,305 96,558 +6,253 +6.92% Shore Network Tech (Linode) 54,051 57,701 +3,650 +6.75%
Fastest growing hosting providers by web-facing computers, December 2012 to June 2013.
Over the last six months DigitalOcean had the fourth largest growth in web-facing computers with only Amazon, Alibaba, and Hetzner ahead of it. DigitalOcean's more than 50-fold growth makes it the 72nd largest hosting provider in the world by web-facing computers, up from 549th in December and 102nd last month. DigitalOcean had the second largest growth of web-facing computers last month — it was one of only five hosting providers to grow by more than 1,000 web-facing computers — and it contributed 10% of the total growth worldwide.
Previous hosting provider Net movement to DigitalOcean New sites +6,211 Rackspace +1,475 Shore Network Tech (Linode) +1,028 Amazon +626 Softlayer +263
Sites (hostnames) switching to DigitalOcean from notable providers, May 2013 to June 2013
As shown in the table above, websites are migrating to DigitalOcean from its better known competitors; last month almost 1,500 websites moved from Rackspace and 1,000 from Shore Network Tech (Linode). NewsBlur, a news aggregation website, is one of the busiest sites hosted at DigitalOcean. Several websites belonging to the Ruby on Rails project including guides.rubyonrails.org and api.rubyonrails.org are now hosted at DigitalOcean after recently moving from Linode.
Operating System share by web-facing computer at DigitalOcean in June 2013
DigitalOcean provide a number of template images in order to create a droplet, including five Linux distributions: Ubuntu, CentOS, Debian, Arch Linux and Fedora. Of the web-facing computers presenting a distribution-specific server banner, Ubuntu is by far the most popular: over 70% of web-facing computers with an identifiable distribution are using the Debian-derived distribution. Microsoft Windows is conspicuous by its absence; DigitalOcean has postponed plans to support Windows citing complexities including licensing and security concerns.
DigitalOcean — 2012 graduate of the Tech Stars startup accelerator — has had difficulty getting access to a sufficient quantity of IPv4 addresses in Amsterdam which meant that it was uneconomic to provide smaller droplet sizes. In May 2013, DigitalOcean announced the availability of further IP addresses for smaller droplet sizes in Europe, re-enabling the creation of 512MB and 1GB droplets.
Netcraft provides information on the Internet infrastructure, including the hosting industry, and web content technologies. For information on the cloud computing industry visit www.netcraft.com.
Netcraft blocked a Twitter phishing site being served from multiple Facebook Applications on 6th June. Visitors to the Facebook applications were requested to enter their Twitter credentials in order to view a "Twitter Video" application. On submission of the fake Twitter login form, the user is redirected to YouTube.
Links to the phishing attack were spread via both public tweets and direct messages. A Twitter direct message can only be sent to and from users who are following each other which lends credence to the message and the link it contains. The message entices the recipient to visit the fraudulent Facebook application: "I'm turning off my page if no one comes farward [sic] regarding this. https://apps.facebook.com/165922313586222".
Facebook — a trusted website which is served over HTTPS — is a useful medium for a fraudster; a Facebook user may be accustomed to seeing legitimate third-party authorisation forms on the social network making a fake login form all the more convincing. Netcraft has also observed similar attacks targeting Facebook itself which are being spread via Facebook statuses.
Twitter phishing via Facebook Apps and Twitter direct messages
Facebook Apps are not hosted on Facebook servers, instead they are hosted by a third party provider. The Facebook Apps involved in this phishing attack were hosted on Heroku and included on facebook.com via an iframe. In September 2011 Facebook partnered with Heroku, simplifying the process of setting up a new Heroku hosting account and Facebook App down to a few clicks. Heroku provides free accounts which are attractive for fraudsters wishing to host phishing attacks on Facebook.
The Facebook App at Heroku has a further iframe showing the actual fake login form, which is hosted at another hosting provider Joe's Datacenter. Both Facebook and the Facebook App hosted at Heroku are served using HTTPS but the final iframe is not, causing some browsers to display an insecure content warning.
Structure of the phishing attack: the fake twitter login form is included in an iframe within the Heroku-hosted Facebook App. The Facebook App is then included on facebook.com within another iframe.
Internet Explorer 9+ blocks HTTP iframes on HTTPS pages by default as it considers them as Mixed Active Content. Firefox currently hides the padlock when viewing mixed content, but does not block it. Firefox 23, due for release later this month, will automatically block iframes when it introduces Mixed Active Content blocking. In Google Chrome, iframes are currently considered passive rather than active, so the padlock icon displays a warning but the content is not blocked. Chrome 29 will switch to treating iframes as Mixed Active Content and block them by default.
Mixed Active Content Blocking in IE10, Pre-release Firefox Nightly, Pre-release Chromium
On 6th June, Netcraft observed the following events (times are GMT). Netcraft had access to both a compromised Twitter account and a second Twitter account which was targeted by the first.
- A Twitter direct message with a link to the phishing attack is received from the compromised account. Netcraft blocks the phishing attack in its Phishing Feed.
- Twitter resets the password on the compromised account: "Twitter believes that your account may have been compromised by a website or service not associated with Twitter. We've reset your password to prevent others from accessing your account". The direct message containing the link to the phishing attack is removed. This is the same email that Twitter sent to 250,000 users in February when it discovered an attack which may have accessed user information.
- Facebook removes the phishing applications Netcraft discovered, but the content is still accessible directly.
Social network credentials are particularly appealing to fraudsters as they have a built-in method to spread the attack without further involvement from the fraudster. Some features, such as attached third-party applications, can make a compromised account even more valuable to a fraudster. Authentication forms of the type imitated in this attack are common and train users to expect to see social media login forms triggered from websites other than that of the social network itself. Despite this attack asking for Twitter credentials within a Facebook App, the fraudster was still able to gather twitter account credentials and use them to further spread the attack using twitter direct messages and tweets.
You can protect yourself against phishing attacks by installing Netcraft's Anti-Phishing Extension. You can help protect the internet community by reporting potential phishing sites to Netcraft by email to email@example.com or at http://toolbar.netcraft.com/report_url. Netcraft can also help protect both brand owners and hosting companies.
The Malaysian government's Police Portal (Johor Contingent) is currently hosting a phishing attack against PayPal on its secure website https://www.polisjohor.gov.my (Site Report). Phishing sites using SSL certificates can piggyback on the trust instilled by browser indicators, such as the padlock icon, to trick potential victims into revealing sensitive information such as their username and password. The SSL certificate used for this phishing attack is irrevocable in some major browsers including Firefox (due to the lack of an OCSP URL in the certificate) and Safari (which doesn't check revocation by default).
A phishing site targeting PayPal hosted on the Malaysian Police's web site which is available over HTTPS.
Fraudsters often use a compromised third party website to host their phishing attack rather than obtaining web hosting directly. By compromising an existing trusted website the fraudster can avoid paying for a potentially suspicious domain name or SSL certificate himself. For example, registering or obtaining an SSL certificate for paypaal.com could draw unwanted attention if the registrar or SSL certificate authority is already conscious of the risk posed by this type of domain name.
The presence of an SSL certificate on a website hosting a phishing site is far from unusual. In May 2013, Netcraft identified 234 trusted SSL certificates on websites with at least one known phishing site. Of these, 67 were issued by Symantec (including the polisjohor.gov.my certificate) which may not be surprising given its leading position in the SSL certificate market. Comodo and Go Daddy had a similar number of such certificates discovered by Netcraft, 42 and 46 respectively. Extended Validation (EV) certificates could be especially valuable to a fraudster as they are designed explicitly to increase the perceived trustworthiness of websites which have passed the validation process by displaying additional indicators such as green bar. During May 2013, Netcraft identified five EV certificates being used on potentially compromised websites: two signed by Symantec and one each signed by Comodo, DigiCert, and Go Daddy.
The SSL certificate for polisjohor.gov.my was issued by GeoTrust (a Symantec brand) back in 2011 and is valid for several more months. If Symantec wished to revoke the certificate to make the site inaccessible over HTTPS it could do so by updating its Certificate Revocation List or by providing on-demand OCSP responses noting its revocation. As examined by Netcraft recently, the current treatment of revocation in many major browsers leaves some room for improvement: this certificate does not contain an OCSP URL so is irrevocable in Firefox. Even if the CA wanted to, it could not directly prevent further use of the certificate in Firefox. Safari users are left unprotected by default as the revocation checking has to be explicitly enabled.
Netcraft offers Phishing alerts to CAs to provide timely alerts to the CA about potential misuse of a certificate. Having access to timely, professionally validated alerts when phishing attacks occur can allow the CA to provide the first alert of a compromise to the webmaster. Both the CA and the webmaster are then able to respond appropriately to the potential compromise, safeguarding the reputation of both parties.
In the June 2013 survey we received responses from 672,985,183 sites, 148k more than last month.
Both Microsoft and Google grew slightly this month, gaining 0.5 percentage points of market share. Microsoft's web server, IIS, now serves 17.22% of the world's websites, down from a historic high of 37% which it reached in October 2007. Microsoft IIS's market share amongst secure websites (HTTPS) is significantly higher: it serves 39% of the secure websites found by Netcraft and is in 2nd place behind Apache. Apache's lead over Microsoft in the secure website market is only slight: it is ahead by just two percentage points and doesn't hold an absolute majority as it does for non-secure websites (HTTP).
Despite its market share dipping slightly, Apache is still significantly ahead of its position just two months ago due to Go Daddy's switch last month to Apache Traffic Server. Within the Million Busiest Sites, Apache bucked its recent downward trend this month: 7,300 more websites than last month are using Apache, including DigiCert's website which switched from nginx to Apache 2.4.5 (2.4.4 is the latest stable release).
nginx's growth within the Million Busiest Sites remains strong, 5,400 more busy websites now use the web server since last month's survey including The Verge which switched from Apache. Across all web sites, however, nginx lost almost 1% of market share and 6.4M websites caused by a large network of websites at namecheap.com failing to respond during the survey.
In early May 2013, nginx released a patch for a high severity security vulnerability which could allow an attacker to execute arbitrary code. Several attacks exploiting the vulnerability in the chunked transfer size calculation have been demonstrated including a proof of concept and an automated metasploit module. Almost 2M websites — or around 2% of all websites using nginx — presented a server banner corresponding to a vulnerable version (1.3.9+ and 1.4.0). The vast majority of nginx websites do not report the version in the server banner; however, the two most popular versions reported are 1.2.1 (released in June 2012) and 1.0.15 (released in April 2012) which do not have this vulnerability but may have others if left unpatched.
nginx is the most commonly used web server at Amazon: it is used on 41% of the 12M websites hosted using EC2 or S3. Last month Netcraft reported Amazon had 158k web-facing computers and has been the largest hosting provider by the number of web-facing computers since September 2012. After nginx, Apache is the next most common web server, 24.7% of websites use it, followed by Microsoft with 14%. Only 1% presented the AmazonS3 server banner, which can be used to host entire static websites in addition to simply static files.
Developer May 2013 Percent June 2013 Percent Change Apache 359,441,468 53.42% 358,974,045 53.34% -0.08 Microsoft 112,303,412 16.69% 115,920,681 17.22% 0.53 nginx 104,411,087 15.52% 97,991,191 14.56% -0.96 23,029,260 3.42% 26,036,616 3.87% 0.45
Rank Performance Graph OS Outage
DNS Connect First
Total 1 Qube Managed Services Linux 0:00:00 0.006 0.099 0.045 0.091 0.091 2 Datapipe FreeBSD 0:00:00 0.009 0.073 0.016 0.033 0.051 3 ServerStack Linux 0:00:00 0.009 0.077 0.066 0.134 0.134 4 Bigstep Linux 0:00:00 0.009 0.269 0.071 0.143 0.143 5 iWeb Linux 0:00:00 0.009 0.121 0.073 0.144 0.144 6 www.dinahosting.com Linux 0:00:00 0.012 0.178 0.098 0.198 0.198 7 XILO Communications Ltd. Linux 0:00:00 0.015 0.218 0.076 0.361 0.517 8 Swishmail FreeBSD 0:00:00 0.018 0.110 0.062 0.124 0.226 9 INetU Windows Server 2008 0:00:00 0.018 0.130 0.072 0.236 0.456 10 Virtual Internet Linux 0:00:00 0.018 0.165 0.074 0.324 0.453
Qube Managed Services had the most reliable hosting company site in May, with only 2 failed requests. Qube specialises in providing managed hosting from three data centres in London, New York and Zurich. Qube was founded in 2001 and provides services to a number of notable clients, including Betfair (a large betting exchange) and blinkbox (a video streaming service from Tesco in the UK). Qube has appeared in the top 10 over twenty times since Netcraft began monitoring it in March 2010 and has now ranked in 1st place four times.
Datapipe and ServerStack placed 2nd and 3rd, both narrowly missing the top spot by a single failed request. Datapipe had the lowest average connection time out of all the top 10 sites, which breaks the tie with ServerStack in its favour. Datapipe has continued to maintain its 100% uptime record having recently passed the 100% uptime over 7 years milestone despite some of its nine data centres being in the path of hurricanes, typhoons, and a snowstorm. Serverstack has now been monitored by Netcraft for seven months and has already appeared in the top 10 four times. The company's 100% uptime SLA offers 5% credit for every half hour of sustained unscheduled downtime.
All but three of May's top 10 most reliable hosting companies hosted their own sites on Linux, including Qube in 1st place, ServerStack in 3rd place and Bigstep in 4th place, which made its debut entry in the table last month. FreeBSD is used by 2nd place Datapipe and last month's winner Swishmail (this month in 8th place). INetU was the only hosting company in the top 10 to host its site on Windows Server 2008.
Netcraft measures and makes available the response times of around forty leading hosting providers' sites. The performance measurements are made at fifteen minute intervals from separate points around the internet, and averages are calculated over the immediately preceding 24 hour period.
From a customer's point of view, the percentage of failed requests is more pertinent than outages on hosting companies' own sites, as this gives a pointer to reliability of routing, and this is why we choose to rank our table by fewest failed requests, rather than shortest periods of outage. In the event the number of failed requests are equal then sites are ranked by average connection times.
Information on the measurement process and current measurements is available.