hosts.equiv(5)
NAME
hosts.equiv - list of hosts and users that are granted "trusted" r command access to your system
DESCRIPTION
The file /etc/hosts.equiv allows or denies hosts and users to use the r-commands (e.g., rlogin, rsh, or rcp) without supplying a password. The file uses the following format: +|[-]hostname|+@netgroup|-@netgroup [+|[-]username|+@netgroup|-@netgroup] The hostname is the name of a host which is logically equivalent to the local host. Users logged into that host are allowed to access like- named user accounts on the local host without supplying a password. The hostname may be (optionally) preceded by a plus (+) sign. If the plus sign is used alone, it allows any host to access your system. You can explicitly deny access to a host by preceding the hostname by a minus (-) sign. Users from that host must always supply additional credentials, including possibly a password. For security reasons you should always use the FQDN of the hostname and not the short hostname. The username entry grants a specific user access to all user accounts (except root) without supplying a password. That means the user is NOT restricted to like-named accounts. The username may be (optionally) preceded by a plus (+) sign. You can also explicitly deny access to a specific user by preceding the username with a minus (-) sign. This says that the user is not trusted no matter what other entries for that host exist. Netgroups can be specified by preceding the netgroup by an @ sign. Be extremely careful when using the plus (+) sign. A simple typographical error could result in a standalone plus sign. A standalone plus sign is a wildcard character that means "any host"!
FILES
/etc/hosts.equiv
NOTES
Some systems will honor the contents of this file only when it has owner root and no write permission for anybody else. Some exceptionally paranoid systems even require that there be no other hard links to the file. Modern systems use the Pluggable Authentication Modules library (PAM). With PAM a standalone plus sign is considered a wildcard character which means "any host" only when the word promiscuous is added to the auth component line in your PAM file for the particular service (e.g., rlogin).
EXAMPLE
Below are some example /etc/host.equiv or ~/.rhosts files.
Allow any user to log in from any host:
+
Allow any user from host with a matching local account to log in:
host
Note: the use of +host is never a valid syntax, including attempting to
specify that any user from the host is allowed.
Allow any user from host to log in:
host +
Note: this is distinct from the previous example since it does not
require a matching local account.
Allow user from host to log in as any non-root user:
host user
Allow all users with matching local accounts from host to log in except
for baduser:
host -baduser
host
Deny all users from host:
-host
Note: the use of -host -user is never a valid syntax, including
attempting to specify that a particular user from the host is not
trusted.
Allow all users with matching local accounts on all hosts in a
netgroup:
+@netgroup
Disallow all users on all hosts in a netgroup:
-@netgroup
Allow all users in a netgroup to log in from host as any non-root user:
host +@netgroup
Allow all users with matching local accounts on all hosts in a netgroup
except baduser:
+@netgroup -baduser
+@netgroup
Note: the deny statements must always precede the allow statements
because the file is processed sequentially until the first matching
rule is found.
SEE ALSO
rhosts(5), rlogind(8), rshd(8)
COLOPHON
This page is part of release 4.09 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
