如何确定传入连接是否正在等待SSL？ [英] How can I determine whether an incoming connection is expecting SSL?

问题描述

我想为未加密的TCP和SSL使用1个端口。

I want to use 1 port for both unencrypted TCP and SSL.

目标是使1个端口成为机器的入口。这意味着将所有协议和传输复制到端口中。例如，我查看流的前4个字节。如果它以GET，POST，HEAD等开头。我知道它是HTTP协议，所以我将连接断开到HTTP服务器。如果是'HELO'或'EHLO'，我知道它将它传递到SMTP服务器。

The goal is to make 1 port the entrance to the machine. That mean to mux all protocols and transports into the port. For example, i peek at the first 4 bytes of the stream. If it begins with 'GET', 'POST', 'HEAD', etc. I know that it is the HTTP protocol so I pass off the connection to the HTTP server. If it is 'HELO' or 'EHLO' i know to pass it off to the SMTP server.

问题是，如果它是一个SSL

The problem is, what do I look for if it is an SSL connection (in order to pass it off to OpenSSL)?

推荐答案

SSL 2将8x yz（十六进制）作为前两个字节（x yz可以是任何值，例如8F 13），SSL 3和以后具有16 03 hex作为前两个字节。

SSL 2 will have 8x yz (hex) as first two bytes (x yz can be anything, eg. 8F 13), and SSL 3 and later have 16 03 hex as first two bytes.

更新：如评论中所指出的，一些协议要求服务器首先发送某些东西（FTP和POP3等等，SMTP在注释中已经提到）因此您的方法只适用于有限数量的协议。

Update: as pointed in the comments, some protocols require the server to send something first (FTP and POP3 to name a few, and SMTP has been mentioned in the comment) so your approach will work only for limited number of protocols.

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