May 2005
Intermediate to advanced
666 pages
21h 5m
English
book
SSH, The Secure Shell: The Definitive Guide, 2nd Edition
by Daniel J. Barrett, Richard E. Silverman, Robert G. Byrnes
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Compatibility Between SSH-1 and SSH-2 Servers
OpenSSH supports both the SSH-1 and SSH-2 protocols within
a single daemon accepting both types of connections. The Protocol keyword can be used to limit the
support to either protocol exclusively. [5.3.7]
For Tectia, however, the story is more complicated. The Tectia
server itself only supports the SSH-2 protocol, but it can accept
connections from clients that request the older SSH-1 protocol. This
backward compatibility is achieved by having the Tectia server run some
other server program for the SSH-1 protocol instead, whenever an SSH-1
connection is requested. This feature is enabled and disabled with the
Tectia Ssh1Compatibility keyword,
given a value of yes or no (the default):
# Tectia
Ssh1Compatibility yesWhen Ssh1Compatibility is
enabled, and an SSH-1 client connects to the Tectia server, the two
programs exchange strings indicating their versions. [3.6.3]
sshd (also known as sshd2, see
the sidebar "Tectia’s
File-Naming Conventions" [5.1]) then locates the
sshd1 executable by examining the value of the
Sshd1Path keyword:
# Tectia
Sshd1Path /usr/local/sbin/sshd1and invokes sshd1. The Tectia server adds the -i option [5.3.3.2] to the sshd1 command line to indicate that the client connection has already been accepted by Tectia, and sshd1 should expect the socket to be attached to its standard input, output, and error streams. In addition, the Tectia server passes the client’s version string using the (mostly undocumented) -V
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.