|May the source be with you, but remember the KISS principle ;-)|
|Contents||Bulletin||Scripting in shell and Perl||Network troubleshooting||History||Humor|
|News||Access Control in Operating Systems||Recommended Links||The umask||SUID/SGID attributes||Sticky attribute (sticky bit) in Unix||File Permissions Hardening|
|World writable files problem||SUID/SGID Checkers||Unix History||Groups administration||Admin Horror Stories||Humor||Etc|
It's important to ensure that your system files are not open for casual editing by users and groups who are not eligible to modify them. Unix separates access control on files and directories according to three characteristics: owner, group, and other. There is always exactly one owner, any number of members of the group, and everyone else.
Default filesystem for Red Hat (ext3) supports ACL with stock 2.6 kernel. Default filesystem for Suse 9 and 10(riesner) support only standard Unix file permissions.
There are several issue in file permission hardening
@users hard core 0 @users hard nproc 50 @users hard rss 5000
This says to prohibit the creation of core files, restrict the number of processes to 50, and restrict memory usage per user to 5M.
You can also use the /etc/login.defs configuration file to set the same limits.
Find all SUID/SGID programs on your system, and keep track of what they are, so you are aware of any changes which could indicate a potential intruder. Use the following command to find all SUID/SGID programs on your system. You can remove the SUID or SGID permissions on a suspicious program with chmod, then restore them back if you absolutely feel it is necessary.
root# find / -perm -2 ! -type l -lsand be sure you know why those files are writable. In the normal course of operation, several files will be world-writable, including some from /dev, and symbolic links, thus the ! -type l which excludes these from the previous find command.
root# find / \( -nouser -o -nogroup \) -print
find /home -name .rhosts -print
# Set the user's default umask umask 033Be sure to make root's umask 077, which will disable read, write, and execute permission for other users, unless explicitly changed using chmod. In this case, newly-created directories would have 744 permissions, obtained by subtracting 033 from 777. Newly-created files using the 033 umask would have permissions of 644.
If you are using Red Hat, and adhere to their user and group ID creation scheme (User Private Groups), it is only necessary to use 002 for a umask. This is due to the fact that the default configuration is one user per group.
It's important to ensure that your system files are not open for casual editing by users and groups who shouldn't be doing that. See World writable files problem
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ABUSE: IPs or network segments from which we detect a stream of probes might be blocked for no less then 90 days. Multiple types of probes increase this period.
Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers : Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism : The Iron Law of Oligarchy : Libertarian Philosophy
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Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 : Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : 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.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law
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 DOS : Programming Languages History : PL/1 : Simula 67 : C : History of GCC development : Scripting 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
The Peter Principle : Parkinson Law : 1984 : The Mythical Man-Month : How 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
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The Last but not Least
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Last modified: October 11, 2015