ssl 层是独立于应用层和传输层的，SSL层的实现有openssl，mozilla的nss。

suse的iso包里包括了nss不需要单独安装

What is Network Security Services (NSS)

NSS is set of libraries, APIs, utilities, and documentation designed to support cross-platform development of security-enabled client and server applications. It provides a complete open-source implementation of the crypto libraries used by Netscape and other companies in the Netscape 6 browser, server products from iPlanet E-Commerce Solutions, the Gateway Connected Touch Pad with Instant AOL, and other products.

How does NSS compare to OpenSSL?

 is an open source project that implements server-side SSL, TLS, and a general-purpose cryptography library. It does not support PKCS #11. It is based on the SSLeay library developed by Eric A. Young and Tim J. Hudson. OpenSSL is widely used in Apache servers and is licensed under an Apache-style licence.

NSS supports both server and client applications as well as  and S/MIME. To permit its use in as many contexts as possible, NSS is licensed under both the  and the . You may choose to use the code either under the terms of the MPL or under the terms of the GPL.

Can I use NSS even if my application protocol isn't HTTP?

Yes, SSL is independent of application protocols. It works with common Internet standard application protocols (HTTP, POP3, FTP, SMTP, etc.) as well as custom application protocols using TCP/IP.

 

https://developer.mozilla.org/zh-CN/docs/NSS_FAQ