SSH, The Secure Shell: The Definitive Guide
Daniel J. Barrett
Language: English
Pages: 670
ISBN: 0596008953
Format: PDF / Kindle (mobi) / ePub
Are you serious about network security? Then check out SSH, the Secure Shell, which provides key-based authentication and transparent encryption for your network connections. It's reliable, robust, and reasonably easy to use, and both free and commercial implementations are widely available for most operating systems. While it doesn't solve every privacy and security problem, SSH eliminates several of them very effectively.Everything you want to know about SSH is in our second edition of SSH, The Secure Shell: The Definitive Guide. This updated book thoroughly covers the latest SSH-2 protocol for system administrators and end users interested in using this increasingly popular TCP/IP-based solution.How does it work? Whenever data is sent to the network, SSH automatically encrypts it. When data reaches its intended recipient, SSH decrypts it. The result is "transparent" encryption-users can work normally, unaware that their communications are already encrypted. SSH supports secure file transfer between computers, secure remote logins, and a unique "tunneling" capability that adds encryption to otherwise insecure network applications. With SSH, users can freely navigate the Internet, and system administrators can secure their networks or perform remote administration.Written for a wide, technical audience, SSH, The Secure Shell: The Definitive Guide covers several implementations of SSH for different operating systems and computing environments. Whether you're an individual running Linux machines at home, a corporate network administrator with thousands of users, or a PC/Mac owner who just wants a secure way to telnet or transfer files between machines, our indispensable guide has you covered. It starts with simple installation and use of SSH, and works its way to in-depth case studies on large, sensitive computer networks.No matter where or how you're shipping information, SSH, The Secure Shell: The Definitive Guide will show you how to do it securely.
connection. The socket may be specified using a domain name or IP address, allowing a name to be resolved on the remote side in a possibly different namespace than the client. These channels are used to implement local TCP forwarding (ssh -L). Preparing for local forwarding is purely a client-side affair: the client simply starts listening on the requested port.* The server first hears of it when a connection actually arrives on the port, whereupon the client opens a direct-tcpip channel with the
number of attacks are based on surreptitiously adding a “+” to someone’s .rhosts file, immediately allowing anyone to rlogin as that user. So, SSH deliberately ignores these wildcards. You’ll see messages to that effect in the server’s debugging output if it encounters such a wildcard: Remote: Ignoring wild host/user names in /etc/shosts.equiv However, there’s still a way to get the effect of a wildcard: using the wildcards available in netgroups. An empty netgroup: empty # nothing here * By
version of OpenSSH is specifically for the OpenBSD Unix operating system, and is in fact included in the base OpenBSD installation. As a separate but related effort, another team maintains a “portable” version that compiles on a variety of Unix flavors and tracks the main development effort. The supported platforms include Linux, Solaris AIX, IRIX, HP/ UX, FreeBSD, NetBSD, and Windows via the Cygwin compatibility library. The portable version carries a “p” suffix. For example, 3.9p1 is the first
several steps are completed beforehand: 1. Get permission from your system administrator. 2. Generate a host key. * Or sshd can be invoked by inetd, creating one sshd process per connection. [5.3.3.2] † OpenSSH also includes /usr/sbin/rcsshd, a symbolic link to the startup script in /etc/init.d. 5.1 Running the Server | This is the Title of the Book, eMatter Edition Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved. 129 Tectia’s File-Naming Conventions At first glance,
"10.1.2.3" Server port = "22" Server version = "SSH Tectia Server 4.1.3.2" ... 12 servers detected. The –s option causes ssh-probe to operate silently, returning only an exit value of 0 to indicate that at least one server was found, 1 if no replies were received, or -1 if some other error occurred: 160 | Chapter 5: Serverwide Configuration This is the Title of the Book, eMatter Edition Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved. # Tectia $ ssh-probe -s 10.1.2.255 $