Know the Technical Difference Between SNI SSL and IP SSL
SSL (Secure Sockets Layer) certificates encrypt the communication between a web server and web browsers to protect sensitive information. There are two main types of SSL certificates – SNI SSL and IP SSL. They differ in how they function and their capabilities.
Main Differences Between SNI SSL vs IP SSL
| SNI SSL | IP SSL |
| Uses SNI to allow multiple certs per IP | One SSL cert per dedicated IP |
| Cost effective as multiple sites share an IP | More expensive as each cert needs one IP |
| Supported on modern browsers | Compatible with all browsers |
| Configuration required on web server | No special configuration needed |
| Compromise of the IP affects all certificates | Compromise of one IP only affects its certificate |
| Seamless SSL renewals and updates | SSL renewals cause downtime |
| Ideal for scaling up sites | Limited scalability due to IP restrictions |
What is SNI SSL?
SNI stands for Server Name Indication. SNI SSL certificates rely on the SNI protocol extension to connect to a web server securely.
With SNI SSL, during the initial SSL handshake between a browser and web server, the browser indicates the hostname of the server it is trying to connect to. The server then sends back the correct certificate for that domain.
This allows hosting multiple SSL secured websites with different domain names on the same IP address. The server can determine which certificate to use based on the hostname indicated by the client.
Benefits of SNI SSL Certificates
- Cost Effective: SNI SSL certificates are less expensive than IP SSL certificates because multiple certificates can be hosted on the same IP address.
- Flexible: SNI removes the limitation of needing a unique IP address per SSL certificate. You can host unlimited SNI SSL secured sites on a single IP.
- Scalable: Adding more SSL secured websites hosted on the server doesn’t require purchasing extra IP addresses. This makes SNI ideal for scaling up.
Drawbacks of SNI SSL
- Compatibility: Older browsers do not support SNI, so the SSL connection may fail on those browsers. This issue is rare today as the majority of traffic is from modern browsers.
- Shared IP: Having multiple SSL certificates on one IP means if the IP address is compromised, all the certificates may be affected.
- Configuration: The web server needs to be configured properly to host multiple SSL sites through SNI. Improper setup can cause SSL errors.
What is IP SSL?
IP SSL certificates use a unique dedicated IP address per certificate.
During the SSL handshake, the browser connects to the destination IP address. The web server uses the corresponding certificate for that IP to establish the encrypted SSL connection.
One IP address can only be bound to one SSL certificate on the server. So each new SSL certificate requires purchasing an additional IP.
Benefits of IP SSL
- Compatibility: IP SSL works on all browsers without issues, since it does not depend on SNI extensions.
- Isolation: Each SSL certificate gets its own dedicated IP address, so if one certificate is compromised, others are not affected.
- Simplicity: IP SSL does not require any special server configuration. The IP-certificate binding happens automatically.
Drawbacks of IP SSL
- Cost: Each IP SSL certificate needs a separate IP, which requires purchasing extra IPs for every added certificate.
- Limited Scalability: The number of SSL sites hosted is restricted by the number of available IP addresses. Adding new SSL sites may mean buying more IPs.
- SSL Reissue Downtime: Updating or renewing an IP SSL certificate requires reissuing and reinstalling it. This causes downtime for that domain until the new certificate propagates.
When Should You Use SNI SSL?
SNI SSL certificates are suitable if:
- You need to host multiple SSL secured websites on one server cost effectively.
- You have limited IP addresses available and cannot dedicate one per SSL certificate.
- You are targeting users on modern browsers that support SNI.
- Your web server supports proper SNI configuration.
- You prefer easier scalability and do not want IP restrictions limiting growth.
- Your sites have relatively low traffic and compromise of the shared IP is unlikely.
When Should You Use IP SSL?
IP SSL certificates are recommended if:
- You need universal browser compatibility including older browsers.
- You have sufficient IP addresses to dedicate one per SSL certificate.
- You want maximum isolation and security: compromising one site should not affect others.
- You want minimal web server configuration and simpler SSL certificate deployment.
- You prefer avoiding potential issues from improper SNI setup.
- Your web traffic is very high and concentrating it on one IP could cause bottlenecks.
Conclusion on SNI SSL vs IP SSL
SNI SSL vs IP SSL both allow setting up SSL encrypted HTTPS websites. SNI is more affordable, flexible, and scalable, making it suitable when hosting multiple sites on limited resources. IP SSL provides broader compatibility and isolation but at increased costs.
Choose SNI SSL for an affordable way to add SSL security to modern browser facing websites. Use IP SSL when compatibility, isolation and simplicity are vital requirements. Evaluate your specific needs, audience, and resources to determine which approach makes more sense.
Frequently Asked Questions
Is SNI SSL as secure as IP SSL?
Yes, SNI SSL provides the same strong 256-bit encryption as IP SSL when implemented properly. The only difference is SNI allows securely hosting multiple certificates on one IP vs one certificate per IP with IP SSL.
Does SNI SSL work on all browsers?
Almost all modern browsers support SNI including Chrome, Firefox, Safari, Opera, Edge and others. Only very outdated browsers do not support it. Over 99% of web traffic today uses SNI compatible browsers.
Can I use both SNI and IP SSL certificates on one server?
Yes, web servers can be configured to host both SNI and IP SSL certificates together. The IP SSL certificates would each get their own dedicated IP addresses while the SNI SSL certificates could share IPs.
Is it safe to share one IP address among multiple SNI SSL certificates?
Generally, it is safe, especially for low-medium traffic sites. For very high traffic sites with valuable sensitive data, isolating certificates on dedicated IPs provides an extra layer of protection. Evaluate your specific security needs.
What happens if I use SNI SSL on an old browser?
On outdated non-SNI browsers, users will get SSL connection errors if trying to access a site hosted on a shared SNI IP. These users should access the site from a modern SNI compatible browser.
Can I switch an IP SSL certificate to use SNI instead?
Yes, you can convert an IP SSL certificate to use SNI instead by reconfiguring the web server appropriately. This allows adding more SSL certificates easily without buying extra IPs.
