版本总结关于SSH的一些总结

在写这篇文章之前，xxx已经写过了几篇关于改版本总结主题的文章,想要了解的朋友可以去翻一下之前的文章

1. 查看sshd的版本

root # rpm -qf /usr/sbin/sshd
openssh-server-4.3p2-82.el5
root # rpm -qi openssh-server-4.3p2-82.el5
Name        : openssh-server               Relocations: (not relocatable)
Version     : 4.3p2                             Vendor: Red Hat, Inc.
Release     : 82.el5                        Build Date: Wed 04 Jan 2012 09:42:39 PM CST
Install Date: Mon 25 Mar 2013 10:02:23 AM CST      Build Host: hs20-bc2-3.build.redhat.com
Group       : System Environment/Daemons    Source RPM: openssh-4.3p2-82.el5.src.rpm
Size        : 491029                           License: BSD
Signature   : DSA/SHA1, Thu 05 Jan 2012 11:55:31 PM CST, Key ID 5326810137017186
Packager    : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
URL         : http://www.openssh.com/portable.html
Summary     : The OpenSSH server daemon
Description :
OpenSSH is a free version of SSH (Secure SHell), a program for logging
into and executing commands on a remote machine. This package contains
the secure shell daemon (sshd). The sshd daemon allows SSH clients to
securely connect to your SSH server. You also need to have the openssh
package installed.

2. ssh的协议层次结构

from: http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_12-4/124_ssh.html

SSH is organized as three protocols that typically run on top of TCP::

Transport Layer Protocol: Provides server authentication, data confidentiality, and data integrity with forward secrecy (that is, if a key is compromised during one session, the knowledge does not affect the security of earlier sessions); the transport layer may optionally provide compression
User Authentication Protocol: Authenticates the user to the server
Connection Protocol: Multiplexes multiple logical communications channels over a single underlying SSH connection

3. 在transport layer protocol中，server端还是client端会先发布自己的版本信息呢？

http://stackoverflow.com/questions/16205240/which-side-will-initiate-the-version-negotiation-in-the-ssh-transport-layer-prot

结论是：协议没有划定，因为这个消息不是request-response。

jsch-0.1.20就存在着问题，先等待server端的版本信息，然后再发自己client端的。需要升级到比拟新的版本处理这个问题。

4. 验证server端sshd版本的一个简单方法

每日一道理
我拽着春姑娘的衣裙，春姑娘把我带到了绿色的世界里。

root # telnet oc26 22

Trying 120.2.13.244...

Connected to oc26.

Escape character is '^]'.
SSH-2.0-OpenSSH_4.3

5. 偶然server端会基于安全的斟酌，故意隐藏ssh的版本信息，下面是一些资料。

http://www.mail-archive.com/ssh@clinet.fi/msg06806.html

http://e-rezaei.persianblog.ir/post/2

http://0x80.org/blog/sshd-hide-version-patch/

http://www.unix.com/solaris/53391-how-hide-ssh-version.html (I just been audited and one the recommendations is to hide the SSH version or give fake information.)

http://www.linuxquestions.org/questions/slackware-14/how-to-hide-openssh-version-331399/

http://serverfault.com/questions/216801/prevent-ssh-from-advertising-its-version-number

http://www.cyberciti.biz/tips/linux-unix-bsd-openssh-server-best-practices.html

6. ssh问题debug的一些方法

http://www.snailbook.com/faq/general-debugging.auto.html

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版本和总结
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