get DHCP information

get DHCP information

Post by Bit Twiste » Fri, 13 Jun 2003 05:30:47

> I'm attempting to duplicate the "ipconfig /all" functionality in windows.
> Specifically I was looking for DHCP lease start and end information. Here's
> what I found out.

> Lease time, client and dhcp server addresses, etc. can be found in
> /var/lib/dhcp/dhclient.leases ascii DB. And of course you can get hostname
> info from other places, e.g. 'hostname'.

> Is there a cmd that pulls it all together and displays it for the user?

You could create a script to cat each file.

Or you could create a script which reads the values and prints them
however you like.   for script info.

Here is my code to dump lease information from  dhcpcd
#*      lease - display lease infomation created by dhcpcd deamon
#*      Information comes from /etc/dhcpc/
#*      Change _nic=eth1 to _nic=eth0, if that is where the lease comes from.
#*      Change _loc=To location of
#*      Do a     locate dhcpcd- | grep info    to find
#*      You may have to do a     updatedb      to create the file location db.
#*      chmod +x lease        after you save this to disk

_nic=eth1                       # nic that the lease is from
_loc=/etc/dhcpc                 # location of

if [ ! -s ${_loc}/dhcpcd-${_nic}.info ] ; then
  echo ${_loc}/dhcpcd-${_nic}.info does not exist
  exit 1

. ${_loc}/dhcpcd-${_nic}.info   # load vars

set `date`
_yy=$6                          # save this year

set `date -r ${_loc}/dhcpcd-${_nic}.info`

_obt="$1 $2 $3 $4 $5"   # save obtained date

        case $2 in
          Jan) _mo=1 ;;
          Feb) _mo=2 ;;
          Mar) _mo=3 ;;
          Apr) _mo=4 ;;
          May) _mo=5 ;;
          Jun) _mo=6 ;;
          Jul) _mo=7 ;;
          Aug) _mo=8 ;;
          Sep) _mo=9 ;;
          Oct) _mo=10 ;;
          Nov) _mo=11 ;;
          Dec) _mo=12 ;;

_lease="${_yy}-${_mo}-$_day ${_time}Z +$LEASETIME seconds"
_new="${_yy}-${_mo}-$_day ${_time}Z +$RENEWALTIME seconds"
_reb="${_yy}-${_mo}-$_day ${_time}Z +$REBINDTIME seconds"

echo " "
echo ${_loc}/dhcpcd-${_nic}.info
echo " "
echo "Obtained  `date -d "$_obt"` "
echo "Renewal           `date -d "$_new"` "
echo "Expires           `date -d "$_lease"` "
echo "Rebind            `date -d "$_reb"` "
echo " "
echo "DNS $DNS "
echo " "

#*************************** end lease **************************************


1. Getting DNS information from DHCP

I have a 3com90x (100 megabit) ethernet card.

I installed Red Hat 6.0 from a FTP site (metalab).  The install
worked fine.  It got an IP address from DHCP and got the
nameserver information.  For the ftp site I typed in

I chose the custom install and installed almost everything off of
the main list, except for some of the image manipulation stuff like
the TeX stuff.

After the install completed and I rebooted I logged in as root, and
tried to ping a site ( and it said it couldn't find
it.  I looked at ifconfig, and eth0 had gotten an ip address and
appeared to be working, as I could ping addresses (no name
server required).

Did I miss something in the install?  Why am I not retrieving name
server information from the DHCP request, or is there something
additional I need?  I noticed in the install there were 2 messages.
 One said it was making a DHCP request, the other said it was
looking up name server and domain information.

The really odd thing is that the very first time I installed Red Hat 6.0
(from ftp), when the system came up, it had the nameserver information
(from DHCP or wherever), but I don't remember doing anything different.

Any help anyone could provide for getting name server information
dynamically would be appreciated.

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