How do I configure a Netdump Server and a Netdump Client?

http://kbase.redhat.com/faq/FAQ_43_2467.shtm

Tutorial on RPM package manager

http://www.digitalhermit.com/linux/rpm

kernel-debuginfo package to analyse vmcore

download kernel-debuginfo package from the following site :

http://updates.redhat.com/pub/redhat/linux/updates/enterprise/4AS/en/os/Debuginfo/i386/RPMS/kernel-debuginfo-2.6.9-42.EL.i686.rpm

This is needed to analyse vmcore using crash utility.

how to save vmcore onto the hard disk

The diskdump utility captures the vmcore onto disk.

diskdumputils package

1. select the dump partition in /etc/sysconfig/diskdump
2. format the dump partition
# service diskdump initialformat
3. enable the service
# chkconfig diskdump on
# service diskdump start
4. verify whether diskdump enabled
If /proc/diskdump exists and it shows the registered dump device, the diskdump has been activated.
# cat /proc/diskdump
5. testing diskdump
To test diskdump, use Alt-SysRq-C or "echo c > /proc/sysrq-trigger". After completing the dump, a vmcore file will be created during the next reboot sequence, and saved in a directory of the name format :
/var/crash/127.0.0.1

crash utility can be used to analyse it.

Linux Networking tutorial

http://yolinux.com/TUTORIALS/LinuxTutorialNetworking.html

Configuring NIS under Red Hat Linux

The following describes a procedure to set up NIS network name service under Red Hat Linux. This is geared toward a small intallation with only one domain. However, it should be fairly evident how to add more NIS domains. The NIS domain name has nothing to do with any DNS naming convention being used.

In these examples, the following conventions are used:
NIS domain: "internal"
Code or configuration file data: colored
Root prompt on NIS master server: master#
Root prompt on NIS client host: client#

Setting up a NIS master server:

Required packages: yp-tools ypbind ypserv portmap

Set up "time" service to run via inetd/xinetd, or configure xntpd, or otherwise make sure the host's clock is synchronized.

Edit /etc/yp.conf:

domain internal server ip.of.nis.server

Edit /etc/ypserv.conf:

dns: no
files: 30
xfr_check_port: yes
* : * : shadow.byname : port
* : * : passwd.adjunct.byname : port

Edit /etc/sysconfig/network:

NISDOMAIN="internal"

Set NIS domain name:

master# domainname internal
master# ypdomainname internal

Create file /var/yp/securenets:

host 127.0.0.1
255.255.255.0   10.0.0.0

Make sure the "portmap" service is running:

master# service portmap start
master# chkconfig portmap on

Portmap will need a rule in /etc/hosts.allow to allow access from localhost and any hosts that need to access NIS.

Start ypserv service:

master# service ypserv start

Check that it's listening:

master# rpcinfo -u localhost ypserv

You should see:

program 100004 version 1 ready and waiting
program 100004 version 2 ready and waiting

Initialize the NIS maps:

master# /usr/lib/yp/ypinit -m

Specify local hostname, Ctrl-D, y, let finish.

Start up ypbind, yppasswdd, ypxfrd:

master# service ypbind start
master# service yppasswdd start
master# service ypxfrd start

Set YP services to run on boot-up:

master# chkconfig ypserv on
master# chkconfig ypbind on
master# chkconfig yppasswdd on
master# chkconfig ypxfrd on

NIS client host setup

Required packages: yp-tools ypbind portmap

Edit /etc/sysconfig/network:

NISDOMAIN=internal

Edit /etc/yp.conf:

domain internal server ip.of.master.server

Edit /etc/hosts:

ip.of.master.server    hostname.domain hostname

Set NIS domain-name:

client# domainname internal
client# ypdomainname internal

Edit /etc/nsswitch.conf:

passwd:     files nis
shadow:     files nis
group:      files nis

Make sure the portmap service is running:

client# service portmap start
client# chkconfig portmap on

The /etc/hosts.allow file will need rules allowing access from localhost and the NIS master server.

Start ypbind service:

client# service ypbind start
client# chkconfig ypbind on

Test it out:

client# rpcinfo -u localhost ypbind
client# ypcat passwd

No Route to Host error and solution

Q. I am getting error that read as No Route to Host. I am trying to ping my ISP gateway as well as DNS server but I am getting this error. How do I solve this problem?
A. This problem indicate networking conflicts or some sort of networking configuration problem.
Here are things to check:
a)Can you ping to your local router interface (such as 192.168.1.254)?
Make sure your card (eth0) is properly configured with correct IP address and router address. Use ifconfig command to configure IP address and route command to setup correct router address. If you prefer to use GUI tools:
redhat-config-network - Works on Red Hat and Fedora Linux/Cent OS.
network-admin - Debian and Other Linux distribution use this GUI too
Use above two GUI tools to setup correct IP address, DNS address and router address.
b) Make sure firewall is not blocking your access
iptables is default firewall on Linux. Run following command to see what iptables rules are setup:
# /sbin/iptables -L -n
You can temporary clear all iptables rules so that you can troubleshoot problem. If you are using Red Hat or Fedora Linux type command:
# /etc/init.d/iptables save
# /etc/init.d/iptables stop
If you are using other Linux distribution type following commands:
# iptables -F
# iptables -X
# iptables -t nat -F
# iptables -t nat -X
# iptables -t mangle -F
# iptables -t mangle -X
c) Finally make sure you are using a router and not a proxy server. Proxy servers are good for Internet browsing but not for other work such as ftp, sending ICMP request and so on.
See also:
List of LINUX troubleshooting commands/tools part # 1

Linux Kernel build guide

http://www.digitalhermit.com/linux/Kernel-Build-HOWTO.html

Linux Kernel Crash Dump facility

LKCD can be found at

http://lkcd.sourceforge.net/

“When kernel fault occurs, LKCD writes a copy of the current system state (memory primarily) into the dump device you specified in advance. The dump device must be a system swap area. A utility called LCRASH is run on the next reboot (before swapping is enabled) to generate a summary of the crash, and optionally to save a copy of the dump in a conventional file. LCRASH can be run interactively and provides a number of debugger-like commands for querying the state of the system.”

Linux Source management

The PatchSet tool can be a useful tool for managing of sources, patches and building kernel.
http://www.csn.ul.ie/~mel/projects/patchset/