My Linux Guide

Linux Hardware and Kernel

Nishant -

* Hardware Resources

–>Kudzu – .It is hardware detection program that typically runs during boot time to detect any added or removed h/w.

.It refers the file/etc/sysconfig/hwconf to deletct any added/removed h/w.

#hwbrowser . Graphical tool that displays the list of detected h/w.

#cd /usr/share/hwdata – This dir. contains the catalogue of supported moniors, v                        ga etc.

Websites: www.tldp.org

hardware.redhat.com/HCL

—> Controlling Kernel Modules (Dynamically loadable device drivers)

* Kernel Module management tools

———————————-

#lsmod — Lists all the kernel modules that are currently loaded into memory (RAM

#rmmod <module_name> – to remove the specified kernel module, if not in use

#insmod <module_name> – to load the specified kernel module. It does not load the dependent modules

#modprob <module_name> – to load the specified kernel module along with its depe                              ndent modules. It refers the kernel /etc/modules.conf b                         efore loading the module.

#modinfo <module_name> – Displays detasil info about the specified kernel module.

locaton of modules

/lib/modules

#vi /etc/modules.conf – kernel module config file.

alias <alias_name> <drive name> ie. alias eth0 8139too

inside the modules.conf,

pre-install

insta;l

post-install

pre-remove

remove

post-remove

see more in #man modules.conf

#lsmod

#ifconfig eth0 down/up to enable/disable ehternet card

#rmmod 8139too – to remove ethernet card driver

#ifup eth0 (to enable the removed driver for ethernet card)

to add ehternet card driver manually

—————————————

#insmod 8139too (this command does not determines the depencies server)

Driver path for ehternet driver

/lib/modulews/2.4.21-4.EL/kernel/drivers/net/8139too.o

#vi /etc/modules.conf

pre-install 8139too server sshd stop

#moprobe 8139too

#lsmod |grep 8139too

#service sshd status

#modinfo 8139too (to see the module info)

— /proc filesystem

.it is vertual filesystem that contains info of running kernel.

.contains system info. providing fles like: cpuinfo, meminfo partitions etc…

#cd /

#ls

cd proc

#ls

#cat cpyinfo

#ls

#cat meminfo

#man proc or #man procinfo

* to turn off ping response

#cat /proc/sys/net/ipv4/icmp_echo_ignore_all (0 for accept incoming echo and

1 for block all request)

#echo “1” >/proc/sys/net/ipv4/icmp_echo_ignore_all (it blocks ping request) this ony for current session

#vi /etc/sysctl.conf

net.ipv4.icmp_echo_ignore_all=1  – to turn off

#sysctl -p ->to activaye changes into the file /etc/sysctl.conf

conclusion (you should know about these things)

1. installaton

2. grub related problem (/etc/grub,conf, gru cli)

.init initialiazation /etc/inittab

.service management (chkconfig & service)

3.  lsmod,rmmod,modprobe /etc/modules.conf

.to turn off ping responses