1 / 13

Why Linux ?

Why Linux ?. Not-so-ancient history Torvalds, Linus Torvalds, 002 the Helsinki University, as a student, low budget, work home rapid and enthusiastic growth from toy to tool ported to almost anything from text mode servers to GUI desktops. Why Linux - continued. A few good reasons

cherie
Download Presentation

Why Linux ?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Why Linux ? • Not-so-ancient history • Torvalds, Linus Torvalds, 002 • the Helsinki University, as a student, low budget, work home • rapid and enthusiastic growth from toy to tool • ported to almost anything • from text mode servers to GUI desktops

  2. Why Linux - continued • A few good reasons • comes with its own sources: high degree of customization possible, most portable OS • stable server platform • wide range of support, from distributors and the community • leave the licensing adventure to the stronger-hearted

  3. The Linux distribution (focus on Red Hat) • Basic OS components of a UNIX system • the kernel – the heart of the OS • system programs – implement the various services required from an operating system • application programs – get useful things done

  4. The Linux distribution (focus on Red Hat) • The bootloader • Choice of alternative OS • Sends boot parameters to the kernel • GRUB vs LILO • User accounts, groups • Root account - no questions asked - careful

  5. The Linux distribution (focus on Red Hat) • The filesystem (common) • Root directory: files that are necessary for booting the system • /root: The home directory for user root. This is usually not accessible to other users on the system • /usr: commands, libraries, manual pages, and user utilities • /var: files that change: spool directories, logs • /bin, /sbin: system programs • /home: users accounts home directories • /etc: system configuration files • /proc: system info • /dev: special device files for all the devices • /mnt: predefined mount point for devices

  6. The Linux distribution (focus on Red Hat) • The package manager • What it does (as opposed to “make install”) • How it works, dependencies: • install • erase • upgrade • queries: finding installed packages, installed files • Rebuilding packages • spec files

  7. Practical aspects - view open ports and check connections [root@bummer download]# netstat -atun Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:6000 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:7741 0.0.0.0:* LISTEN tcp 0 0 192.168.1.64:52479 83.140.65.8:80 ESTABLISHED tcp 0 0 192.168.1.64:50956 83.140.65.8:80 ESTABLISHED tcp 0 0 192.168.1.64:48980 83.140.65.8:80 ESTABLISHED tcp 0 0 192.168.1.64:39254 192.168.1.199:993 ESTABLISHED tcp 0 0 192.168.1.64:53081 216.155.193.157:5050 ESTABLISHED tcp 0 0 192.168.1.64:49203 217.74.209.135:5223 ESTABLISHED tcp 0 0 192.168.1.64:40836 192.168.1.63:3389 ESTABLISHED

  8. Practical aspects - view open ports - continued • firewalls filter open ports; scan from another machine

  9. Practical aspects – startup services • ntsysv lets you select system services to be started at boot time (for the current runlevel) • chkconfig –list (all runlevels)

  10. Practical aspects – startup services (continued) – on demand services # less /etc/xinetd.d/ftp service ftp { socket_type = stream protocol = tcp wait = no user = root server = /usr/bin/ftpd disable = no only-from = 192.168.200.3 192.168.200.7 192.168.200.9 only-from += 192.168.200.10 192.168.200.12 172.16.0.0 no_access = 172.16.{1,2,3,10} access_times = 07:00-21:00 }

  11. Practical aspects – check your system • find files modified within the last 24 hrs • find / -mtime 1 • spot largest files (numeric sort on 5th col) • ls –lR | sort +4n • find which process uses most memory • ps aux | sort +4n • Check available space • df -h

  12. Practical aspects – the package manager • find packages containing string rpm –qa | grep string • find files installed by a package rpm –ql <package name> • find all files installed by Open Office packages rpm –ql $(rpm –qa| grep openoffice) | less • find all files installed by each package for i in $(rpm -qa | sort); do echo $i; rpm -ql $i; done

  13. Practical aspects – patching the system • System updates • deal with • software bugs • vulnerabilities • dependency checking • up2date – use the source • apt, yum

More Related