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Project Spacewalk: Red Hat Open Sourced RHN Software

Today, at the Red Hat Summit in Boston, Mass., Red Hat introduced Project Spacewalk. RHN has provided patches and software for Red Hat Enterprise Linux operating system. Spacewalk is an open source (GPLv2) Linux systems management solution. It is the upstream community project from which the Red Hat Network Satellite product is derived. From the press release:

Spacewalk is the upstream project upon which RHN Satellite will now be based. Spacewalk will work with Red Hat Enterprise Linux, Fedora and other Red Hat Enterprise Linux derivative distributions like CentOS and Scientific Linux. Spacewalk will bring together a growing community of new users along with seasoned systems management veterans. In this way, the Satellite product can grow (as Linux itself does) with the combined efforts of the open source leader, Red Hat, and an invigorated community. Both will work together to expand the capabilities and stature of the upstream project. This will translate into faster adoption of new, innovative ideas and technologies into the downstream Satellite product.

(Fig.01: Spacewalk in action)

=> You can download spacewalk software here.

Setup OpenLDAP authentication on Linux for OSX Client and sync / share home directory

Finally, someone spends time to work with a Linux server and OS X authentication issue:

OSX has what I would call an undocumented feature of the operating system- the portable home directory. Basically, it keeps a user's home directory sync'd up between a network share and the local pc. If you are not on the network you work on the local home directory. Whenever you login on the network, the mirror agent running on the local pc synchronizes the two directories.

Full Stack: Portable Home Directory over NFS on OSX authenticated via OpenLDAP on Debian Linux

Howto: Ubuntu Linux convert DHCP network configuration to static IP configuration

My friend wanted to know how to change or convert DHCP network configuration to static configuration. After initial installation, he wanted to change network settings. Further, his system is w/o GUI system aka X Windows. Here is quick way to accomplish the same:

Your main network configuration file is /etc/network/interfaces

Desired new sample settings:
=> Host IP address
=> Netmask:
=> Network ID:
=> Broadcast IP:
=> Gateway/Router IP:
=> DNS Server:

Open network configuration file
$ sudo vi /etc/network/interfacesOR$ sudo nano /etc/network/interfaces

Find and remove dhcp entry:
iface eth0 inet dhcp

Append new network settings:

iface eth0 inet static

Save and close the file. Restart the network:
$ sudo /etc/init.d/networking restart

Task: Define new DNS servers

Open /etc/resolv.conf file
$ sudo vi /etc/resolv.conf

You need to remove old DNS server assigned by DHCP server:
search myisp.com

Save and close the file.

Task: Test DNS server

$ host cyberciti.biz

Network command line cheat sheet

You can also use commands to change settings. Please note that these settings are temporary and not the permanent. Use above method to make network changes permanent or GUI tool as described below.

Task: Display network interface information

$ ifconfig

Task: Take down network interface eth0 / take a network interface down

$ sudo ifconfig eth0 downOR $ sudo ifdown eth0

Task: Bring a network interface eth0 up

$ sudo ifconfig eth0 upOR$ sudo ifup eth0

Task: Change IP address and netmask from command line

Activate network interface eth0 with a new IP ( / netmask:
$ sudo ifconfig eth0 netmask up

Task: Display the routing table

$ /sbin/route OR$ /sbin/route -n

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
localnet        *        U     0      0        0 ra0    *        U     0      0        0 eth0    *        U     0      0        0 eth1
default         UG    0      0        0 ra0

Task: Add a new gateway

$ sudo route add default gw

Task: Display current active Internet connections (servers and established connection)

$ netstat -nat

Task: Display open ports

$ sudo netstat -tulpOR$ sudo netstat -tulpn

Task: Display network interfaces stats (RX/TX etc)

$ netstat -i

Task: Display output for active/established connections only

$ netstat -e
$ netstat -te
$ netstat -tue


  • -t : TCP connections
  • -u : UDP connections
  • -e : Established

Task: Test network connectivity

Send ICMP ECHO_REQUEST to network hosts, routers, servers etc with ping command. This verifies connectivity exists between local host and remote network system:
$ ping router
$ ping
$ ping cyberciti.biz

See simple Linux system monitoring with ping command and scripts for more information.

Task: Use GUI (Graphical Configuration) network Tool

If you are new, use GUI configuration tool, type the following command at terminal:
$ network-admin &

Above command is Ubuntu's GUI for configuring network connections tool.

Final tip - Learn how find out more information about commands

A man page is your best friend when you wanted to learn more about particular command or syntax. For example, read detailed information about ifconfig and netstat command:
$ man ifconfig
$ man netstat

Just get a short help with all command options by appending --help option to each command:
$ netstat --help

Find out what command is used for particular task by searching the short descriptions and manual page names for the keyword:
$ man -k 'delete directory'
$ apropos -s 1 remove

Display short descriptions of a command:
$ whatis rm
$ whatis netstat

Linux offers an excellent collection of utilities, which can be use to finding the files and executables, remember you cannot memorize all the commands and files ;)