Linux Porting

1
Linux Porting Routing

• 9th May 2006
• Kim Su Min
• CNR, EECS, KAIST
• smkim_at_cnr.kaist.ac.kr

2
Contents

• Linux Overview
• Linux Compiling
• Routing in Linux
• Announcements
• Pre-Lab
• Main-Lab
• References

3
Linux Overview

• Linux
• 1989, Linuz Torvalds (Finland)
• Free Operating System
• Open Source Code
• Linux is composed of
• Boot
• Scheduler multi-process
• Memory-management virtual memory
• File system
• Network protocols and routing facilities
• Terminal handling

4
Linux Compiling (1/6)

• Kernel version
• Redhat 9.0 supports kernel version 2.4.20
• We will use kernel version 2.4.21
• Download kernel source
• Access to ftp.kr.kernel.org
• Then, access to /pub/linux/kernel/v.24/
• Download linux-2.4.21.tar.gz (33.8MB)
• Decompress this file in temporal directory
  (/usr/src/linux2)
• These are kernel source files

5
Linux Compiling (2/6)

• Architecture of kernel source

6
Linux Compiling (3/6)

• Configuration
• Location kernel source directory
  (/usr/src/linux2)
• Command make menuconfig (or xconfig)
• Choose options
• exclude
• include in kernel
• M install in kernel as module

7
Linux Compiling (4/6)

• Kernel compile
• Location kernel source directory(/usr/src/linux2
  )
• Command make dep
• Make dependency between source and reference
  files to compile kernel
• Command make clean
• Delete unnecessary files (object, temporal files,
  etc)
• Command make bzImage
• Create kernel image file
• Created directory /usr/src/linux-2.4/arch/i386/b
  oot
• Command make modules make modules_install
• Make object files (modules) about device driver
  of Ethernet Cardand copy them into module
  directory
• Copy this new kernel
• cp /usr/src/linux-2.4/arch/i386/boot/bzImage
  /boot/linux-2.4.21

8
Linux Compiling (5/6)

• Edit LILO
• Command vi /etc/lilo.conf
• Add to the following into the configuration file

9
Linux Compiling (6/6)

• Rebooting
• Command shutdown r now or reboot
• (cf. Halt Command shutdown h now or halt)
• LILO is executed every booting time.
• LInux LOader
• Kernel Selection (choosing kernel 2.4.21)

10
Routing in Linux (1/3)

• Routing
• Store-and-Forward

11
Routing in Linux (2/3)

• Routing Table
• Routing Table
• Route command (show route table) /sbin/route
• Route Add command route add host
  143.248.148.155 gw 143.248.148.22 eth0
• Result of Route Add
• Route Delete command route del host
  143.248.148.155 eth0

12
Routing in Linux (3/3)

• Routing Cache
• Route cache command (show route cache table)
  /sbin/route C
• IP forwarding
• Command echo 1gt /proc/sys/net/ipv4/ip_forward
• Routing test
• Command ping, traceroute

13
Pre-Lab

• Find all options related with routing in kernel
  compile.(during make menuconfig)
• Explain the differences among bridge, router, and
  gateway. NET
• Survey linux commands to check routing table. (at
  least 2) RT
• Check the meaning of each entry in routing table
  and when and where the entry is used. TCP, RT
• What is hashing.
• How does Linux deal with excessive incoming
  traffic that exceeds its handling ability.
• Due date pm 1159, 16th May (Tuesday)
• Location Box in the Chips building 1st floor

14
Main-Lab (1/2)

• Compile kernel
• Use Redhat 9.0 (And append the kernel 2.4.21)
• Compile kernel with minimum options to support
  routing according to the process in the document
• Modify lilo.conf
• Reboot and select new kernel
• Check if the new kernel behaves correctly
• Modify routing table
• Check current routing table
• Modify it to make A always send packets to C
  through B(A and B are Linux machine and in the
  same LAN, C can be any arbitrary host in
  Internet)

15
Main-Lab (2/2)

• Modify routing code
• Explain the functions net_bh(), ip_rcv(),
  ip_route_input(), ip_route_input_slow(). And
  insert a code line in each function in order to
  print the function name when each function is
  executed.
• Explain the ICMP redirect message and the
  function ip_rt_send_redirect(). And insert a code
  line in this function in order to print ICMP
  message sent when the ICMP redirect message is
  sent. (To see ICMP redirect message, C in 2.b
  must be in the same LAN.) TCP
• ltHintgt
• - net_bh() /proc/sys/net/core/dev.c
• - ip_rcv() /proc/sys/net/ipv4/ip_input.
  c
• - ip_route_input() /proc/sys/net/ipv4/r
  oute.c
• - ip_route_input_slow()
  /proc/sys/net/ipv4/route.c
• - ip_rt_send_redirect()
  /proc/sys/net/ipv4/route.c
• - print function for kernel printk()
  usage is similar to printf()
• exgt printk(net_bh() has been
  executed!!)
• Due date pm 1159, 26th May (Friday)
• Location Box in the Chips building 1st floor

16
References

• OS The Design and Implementation of the 4.4 BSD
  Operating System, Marshall K. McKusick, and 3
  more, Addison Wesley
• TCP TCP/IP illustrated volume 1, Stevens,
  Addison Wesley
• NET An Engineering Approach to Computer
  Networking, Keshav, Addison Wesley
• RT http//kldp.org
• - Korea Linux Documentation Project
• IP Linux IP Networking, Glenn Herrin