Transferring files securely over networks is critical for both individuals and organizations. But with a dizzying array of cryptic protocols available today, most get baffled on the best approach.
If you deal with remote file transfers and security is paramount, chances are you have come across acronyms like SFTP and FTPS. They sound incredibly alike, but differ wildly when you peek under the hood!
This guide will unpack everything you need to know around SFTP and FTPS in remarkably simple terms. We‘ll peel back the arcane technical layers to reveal the core differences. By the end, you‘ll have complete clarity on picking the right secure transfer protocol for your needs.
Let‘s start by quickly understanding what SFTP and FTPS try achieving:
SFTP stands for SSH File Transfer Protocol. It allows transferring files through an encrypted SSH tunnel. So it combines the bulletproof security of SSH with the file exchange convenience of FTP.
FTPS refers to FTP over SSL or Transport Layer Security. It essentially adds SSL/TLS encryption on top of regular FTP operations to make it secure.
Now let‘s dig deeper into their distinct technical approaches, capabilities and use cases.
A Quick History Recap
First, some background on where they come from.
The File Transfer Protocol (FTP) published its first standards document (RFC 114) way back in 1971. It laid the foundation for client-server file transfers over TCP networks.
But FTP had one gaping flaw – it did not encrypt data during transfers at all!
Enter FTPS
To plug this hole, FTP over SSL (later TLS) emerged in 1997. It sandwiches the FTP process between two SSL cryptographic layers to create a secure tunnel for transfers. Users authenticate via SSL certificates on both ends.
Over the years, FTPS saw widespread adoption. It extended secure connections to legacy applications relying on plain old FTP. Almost all modern FTP servers now support FTPS using OpenSSL or other SSL/TLS implementations.
And SFTP
In parallel, SSH File Transfer Protocol piggybacked off SSH protocol version 2 functionality when it launched in 1996.
SSH already provided strong symmetric encryption, data integrity checks and server authentication out of the box. SFTP neatly layered file transfers on top by reusing the same secure session, connection and cryptographic primitives.
This allowed it to blend FTP‘s flexibility with the bulletproof security foundations of SSH seamlessly.
Now let‘s move on to side-by-side comparison across several axes:
Authentication and Encryption
| SFTP | FTPS |
|---|---|
| Leverages SSH protocol for encryption and host authentication. Support all SSH ciphers including AES, Blowfish etc. | Implements SSL/TLS for encryption tunnelling. RSA, AES, RC4 common. |
| Public key authenticaton using locally stored keys is common. Password and hostbasedSSH auth also valid. | Authenticates using CA-verified X.509 certificates mandatory in SSL/TLS. Username+password also possible. |
| Integrity confirmation happens via SHA-1 or MD5 hashes. Compression also frequently enabled. | Integrity via hashing functions like SHA-1, MD5. Lacks compression. |
A key benefit of SFTP is its extensive cryptographic agility inherited from SSH. It can utilize a variety of symmetric ciphers, asymmetric encryption and hashing algorithms battle-hardened by decades of SSH use.
FTPS relies on the robustness of the SSL/TLS ecosystem. But certificate issuance, revocation management and key infrastructure introduce liabilities. Real-world attacks often target SSL/TLS cracking rather than SFTP.
Ports and Connections
Another vital area of difference is in how ports get handled:
SFTP rides a single encrypted SSH connection, typically on the usual SSH port 22. Both control commands and data transfers utilize this sole channel. SSH port forwarding magic seamlessly tunnels whatever runs over it.
But FTPS needs multiple TCP connections to function:
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Port 21 handles good old FTP control communication
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Port 20 opens the default data channel
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Additionally, Ports 989 or 990 open an explicit SSL-wrapped secure data session
So external firewalls must allow these inbound connections, while correctly mapping return data traffic to internal addressses. Statefull inspection firewalls help, but misconfigurations easily break FTPS transfers.
In contrast, a solitary port 22 ingress for all activities simplifies SFTP traversal across firewalls tremendously. Routing a single port is infinitely more straightforward!
Native OS Support and Convenience
Today, SFTP runs out of the box on almost all modern endpoints you‘d want to transfer files between:
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Windows integrates dedicated SFTP support since Vista and Windows Server 2003
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Most Linux distributions have OpenSSH packages preinstalled or installable in one command
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macOS, OS X have inbuilt SSH services for SFTP
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iOS, Android and even Chromebooks now play well with SFTP too!
In comparison, fractured FTPS implementations vary across server and client versions. Mismatched equipment easily causes loss of connectivity. CAs choice further fragments compatibility. Getting FTPS clients and servers to mutually authenticate needs meticulous planning.
Furthermore, enabling SFTP needs only flipping a switch to turn on SSH access – keys authenticate passwordless logins. But FTPS requires extensive certificate issuance and distribution overhead.
Network Address Translation Handling
Behind the scenes, Network Address Translation (NAT) gateways frequently route private IP traffic to public destinations. Extra hops can wreck protocols.
Thanks to intrinsic design foresight, SFTP handles NAT gracefully. SSH tunnels transparently traverse address translation devices without breaking a sweat. FTP has no such superpowers!
So when tailgating SFTP transfers behind NAT hardware, sessions persist reliably from LAN devices out onto the internet. But FTPS chokes at the slightest mismatch in IP addressing between local and global endpoints. Even simple restarts of NAT appliances mid-transfer tend to cripple FTPS.
Speed and Performance Optimization
A key strength of SFTP is extensive optimization for minimal resource consumption:
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Compression crunches files into smaller pieces before pushing across. This accelerates transfers notably.
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Caching minimizes duplicate data transmission.
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Pipelining queues multiple file tasks in one go rather than awaiting individual responses.
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Persistent connections recycle links minimizing overheads.
In contrast, FTPS inherits none of the performance enhancement capabilities of FTP extensions like MODE Z. Every ounce of processing cycles goes towards strong encryption, integrity checks and certificate management. No spare room remains for compression or caching.
While both SFTP and FTPS take throughput hits from encryption, SFTP‘s efficient design squeezed speed far beyond expectations. Peak transfer rates still comfortably outpace FTPS. Latencies benefit too on long distance connections.
Security – The Bottom Line
FTPS seems intrinsically more secure as it layers FTP directly into SSL rather than the SSH detour taken by SFTP.
But interestingly, SFTP still emerges safer by design owing to:
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More rigorous ciphers lifted transparently from SSH.
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No dependence on questionable certificate authorities or infrastructure.
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Fewer moving parts overall minimize exposure surface.
So theoretically and empirically, SFTP hits the sweet spot providing watertight data protection without compromise on trust or convenience.
Of course, FTPS offers adequate defences for most purposes too. But experts agree SFTP builds on proven methodologies to deliver best overall security.
SFTP vs FTPS – Which one should you use?
Considering their technical contrast across all aspects, when should you pick one over the other? Here are some recommendations:
Prefer SFTP when:
- Command line usage dominates – automation friendly
- Cross-platform access critical
- Bandwidth constrained networks
- Firewalls/NAT gateways in play
- Highest security imperative
- No other existed protocol preferences
Choose FTPS for:
- Rigid FTP dependency in workflow
- Tight bind with legacy non-SFTP equipment
- Certificate authority readily available
- Domain specific use cases e.g. mainframes
Conclusion
We‘ve covered a ton of ground contrasting SFTP and FTPS! Let‘s round up the key takeways:
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SFTP combines FTP file transfer flexibility with SSH rock-solid encryption, authentication and integrity protection.
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FTPS attempts retrofitting SSL/TLS encryption security onto regular old FTP.
Overall, SFTP emerges the safer, faster and more convenient protocol. It handles modern networks with elan thanks to intelligent optimizations absent in FTPS.
However, some unique use cases do mandate older protocols. There FTPS brings acredible midway upgrade to plain FTP.
Hopefully this guide helped demystify the critical differences between the two. Making sense of all the tech jargon is key before pointing your next file transfer protocol decision!
