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Restricted Shell

Restricted shells allow you to control the user's environment. The restricted shell, rsh, allows the user to do everything allowed by sh, except:

The restricted shell is /usr/lib/rsh. This should not be confused with the remote shell, which is /usr/bin/rsh.

Don't rely too heavily on the restricted shell. It's not that restricted. While you can't specify a command name that begins with "/", you can specify arguments that do. So if cat is in your path you could type:

% cat /etc/passwd

and have a look at the password file. Also, some programs, such as editors and telnet, allow you to escape out to a shell and editors can edit/view any file with read access allowed on the system.

If Bash is started with the name rbash, or the `--restricted' option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. A restricted shell behaves identically to bash with the exception that the following are disallowed:

How do I break out of a restricted shell?

A restricted shell is a shell that has been modified to allow you to do fewer things than a normal shell would allow you to do. It may allow you to run only certain programs. It may stop you from changing directories. Many sites run their own restricted shells to allow limited use of their systems over the Internet. Restricted shells often make use of the restricted shell (rsh).

On poorly implemented restricted shells you can break out of the restricted environment by running a program that features a shell function. A good example of a shell function is provided by vi. Run vi and use this command:

:set shell=/bin/sh

then shell using this command:

:shell

Many menu based restricted shells will allow you to configure your user environment, or to run programs that allow you to configure your user environment. Look for configuration options that refer to executable programs. If the program lets you define an editor, for example, try to set your editor to "/bin/csh -i -f"

If you are not allowed to read files, try to open them inside the e-mail program.

If you are not allowed to edit files, try to save that to file from the e-mail program.

If your restricted shell prevents you from using the "cd" command, try to FTP into your account and change directories. FTP can aso be used to edit files by getting the file, editing it offline, and putting the net file back online.

Like most hacking, trying different things is often the most successful strategy.



Etc

Society

Groupthink : Understanding Micromanagers and Control Freaks : Toxic Managers : BureaucraciesHarvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Two Party System as Polyarchy : Neoliberalism  : The Iron Law of Oligarchy : Libertarian Philosophy

Quotes

Skeptical Finance : John Kenneth Galbraith : Keynes : George Carlin : Skeptics : Propaganda  : SE quotes : Language Design and Programming Quotes : Random IT-related quotes : Oscar Wilde : Talleyrand : Somerset Maugham : War and Peace : Marcus Aurelius : Eric Hoffer : Kurt Vonnegut : Otto Von Bismarck : Winston Churchill : Napoleon Bonaparte : Ambrose Bierce : Oscar Wilde : Bernard Shaw : Mark Twain Quotes

Bulletin:

Vol 26, No.1 (January, 2013) Object-Oriented Cult : Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks: The efficient markets hypothesis : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Vol 23, No.10 (October, 2011) An observation about corporate security departments : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law

History:

Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds  : Larry Wall  : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOSProgramming Languages History : PL/1 : Simula 67 : C : History of GCC developmentScripting Languages : Perl history   : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history

Classic books:

The Peter Principle : Parkinson Law : 1984 : The Mythical Man-MonthHow to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Haterís Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite

Most popular humor pages:

Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor

 

The Last but not Least


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Last modified: July 07, 2013