{"id":104,"date":"2019-07-09T07:31:16","date_gmt":"2019-07-09T07:31:16","guid":{"rendered":"https:\/\/www.ssls.com\/knowledgebase\/?p=104"},"modified":"2023-11-02T13:01:05","modified_gmt":"2023-11-02T13:01:05","slug":"what-is-sni-technology","status":"publish","type":"post","link":"https:\/\/www.ssls.com\/knowledgebase\/what-is-sni-technology\/","title":{"rendered":"What is SNI technology?"},"content":{"rendered":"

How it worked prior to SNI implementation<\/span><\/a><\/p>\n

SNI as a solution<\/span><\/a><\/p>\n

Applications that support SNI<\/span><\/a><\/p>\n

How to configure SNI<\/span><\/a><\/p>\n

SNI stands for Server Name Indication and is an extension of the TLS protocol. It indicates which hostname is being contacted by the browser at the beginning of the handshake process. This technology allows a server to connect multiple SSL Certificates to one IP address and gate.<\/span><\/p>\n

How it worked prior to SNI implementation<\/h2>\n

When someone visits your website, their web browser\/client connects with the web server and sends it the name and domain name of the webpage. When making an SSL\/TLS connection, the process becomes a little more complicated. The browser will require a digital certificate from the server, before it even knows what page the browser wishes to access. Then it will compare the name on the certificate from the server with the name of the page it is trying to make a connection with.<\/span><\/p>\n

If the names match, the connection will be made in an ordinary way.<\/span><\/p>\n

When the names do not match, the visitor will not see your website but a warning message, possibly followed by a disconnect from the website, as the failed connection could indicate a man-in-the-middle attack.<\/span><\/p>\n

To prevent this, websites that use SSLs are required to have their own IP addresses. This allows the web server to use the IP address to check which website the visitor wants to connect to and send the right certificate to the browser or client.<\/span><\/p>\n

SNI as a solution<\/h2>\n

As the number of IP addresses is limited, requiring every website to have its own IP address may cause problems in the long term. Server Name Indication (SNI) is the solution to this problem. Browsers that support SNI will immediately communicate the name of the website the visitor wants to connect to, during the initialization of the secured connection, so that the server knows which certificate to send back. This allows browsers\/clients and servers supporting SNI to connect multiple certificates for multiple domains to one IP address. So, your website visitor will not notice any differences.<\/span><\/p>\n

<\/span><\/p>\n

SNI technology is quite new. Its implementation was taking place from 2004 to 2007.<\/span><\/p>\n

In order to implement this technology, TLS library of the application must include SNI and this application should pass the hostname to the TLS library.<\/span><\/p>\n

Moreover, \u00a0the TLS library may either be included in the application program or be a component of the operating system in question. Because of this issue, some browsers implement SNI when running on any operating system, while others implement it only when running on certain operating systems.<\/span><\/p>\n

If you want the full technical details on SNI, you can read the relevant <\/span>RFC<\/span><\/a>.<\/span><\/p>\n

Applications that support SNI<\/h2>\n

Web-browsers<\/h3>\n