dhcpcd (Pete's notes)

• at boot time by the startup scripts to configure the latop's built-in Ethernet interface, which is the same as the port replicator interface
• when a PCMCIA Ethernet or wireless card is inserted If you need to control dhcpcd, like add some command line options, you have to do it in different places depending on the scenario.

  At boot time under Red Hat 7.3, /etc/init.d/network logs

  Bringing up interface eth0:

  and runs /etc/sysconfig/network-scripts/ifup, which sources /etc/sysconfig/network-scripts/ifcfg-eth0, which sets BOOTPROTO='dhcp'. This causes ifup to set DYNCONFIG=true when it's configuring eth0, which makes ifup execute its dhcpcd startup code. When the code executes, you get a

  Determining IP information for eth0

  message in /var/log/messages. Then dhcpcd runs /etc/dhcpcd/dhcpcd.exe, which fixes up /etc/resolv.conf.

  When connected at home, the Cisco 770 ISDN router generates infinite lease times, even though its configured not to. Infinite lease times cause dhcpcd to syslog

  infinite IP address lease time. Exiting

  and die. To fix this, I edited /etc/sysconfig/network-scripts/ifcfg-eth0 and added

  DHCPCDARGS='-l 86400 -t 5'

  This causes dhcpcd to ask the server for a lease time of 24 hours. The server grants the request, and dhcpcd doesn't die. This makes life more predictable.

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  !!!!!!!!!!!!! WHAT FOLLOWS IS THE OBSOLETE SUSE STUFF

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  Get and install dhcpcd

  SuSE Linux camne with dhcpcd 1.3.18-p8. I had some problems with it when I upgraded my kernel to 2.4.3, so I got the latest version. There were plenty of bug fixes since 1.3.18-p8, so this was a good idea.

  First, use YAST to delete any exisitng dhcpcd.

  Web to the dhcpcd-1.3 home page.

  cd /usr/src
ftp gate.ucar.edu
anonymous@ftp.phystech.com
siemsen@ucar.edu
cd pub
binary
get dhcpcd-1.3.20-pl0.tar.gz
quit
gunzip dhcpcd-1.3.20-pl0.tar.gz
tar xf dhcpcd-1.3.20-pl0.tar
rm dhcpcd-1.3.20-pl0.tar
cd dhcpcd-1.3.20-pl0
./configure
make
make install
make clean


  Introduction

  The DHCP client daemon is dhcpcd. SuSE wants you to run the dhclient startup script, but I find that it fails consistently because the 2com PCMCIA card is inserted but there's no cable plugged into the card. The dhclient script looks at SuSE configuration variables and calls dhcpcd in different ways. It also reads state files in /var/state/dhcp, which cna sometimes confuse things. Dhcpcd requires that an existing device name be supplied on the command line.

  Dhcpcd maintains state files in /var/state/dhcp. In one of the files, it caches the last-assigned IP address. When it runs again, it tries to use the IP address that it was previously assigned, to try to make the machine have the same IP address over time. In my environment, where I bounce back and forth between work and home, this breaks. It also causes confusion. For example, if I docked at work and run "sudo dhcpcd -d eth0" it sometimes hangs. Inspecting /var/log/messages shows broadcasting DHCP_REQUEST for 10.0.0.2 and then terminating on signal 2. This means that dhcpcd is trying to get a lease for the IP address that I use at home. When it doesn't, it hangs.

  To see how the ISDN router at home is configured to do DHCP, see the ISDN page.

  The dhclient startup script in /etc/rc.d is run at boot time and at shutdown time. It runs dhcpcd. If dhcpcd gets a lease with a time of 0 (infinite), then dhcpcd will set the values and exit. If the lease time isn't 0, dhcpcd will hang around as a daemon, in case the DHCP server wants to converse with it later. The NCAR DHCP server hands out leases with non-zero times, so when I'm docked at NCAR, the dhcpcd process exists. The ISDN router hands out leases with infinite times, so when I'm docked at home, the dhcpcd process doesn't exist. During a halt or reboot, the dhclient script is run, and tries to kill down the dhcpcd process. At home, the process doesn't exist, so an annoying error message is displayed during shutdown. I couldn't seem to get the ISDN router to hand out leases with non-zero times, so to solve this, use the "-l" option in the dhcpcd command line to request a non-zero time.

  Don't start up the DHCP server

  This is controlled by START_DHCPD variable in /etc/rc.config. I didn't know this, so I deleted the links in /etc/rc.d as follows. No big deal.

  rm /etc/rc.d/rc2.d/K30dhcp
rm /etc/rc.d/rc2.d/S30dhcp
rm /etc/rc.d/rc3.d/K30dhcp
rm /etc/rc.d/rc3.d/S30dhcp


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  Pete Siemsen
  Last modified: Mon Oct 21 13:15:31 MDT 2002