EndRun Tempus LX GPS, User Manual, Page: 33 / 116

T e m p u s L X G P S U s e r M a n u a l 20
C H A P T E R T H R E E
21 T e m p u s L X G P S U s e r M a n u a l
S E T T I N G U P N T P C L I E N T S O N U N I X - L I K E P L A T F O R M S
• You have successfully performed the Basic NTP Client Setup on your client computer.
Create the ntp.keys File
You must create a file named ntp.keys in the /etc directory. It must be a copy of the one residing in
the
/etc
directory of your Tempus LX. You can
telnet
into your Tempus LX and start an
ftp
ses-
sion with your client computer to send the Tempus LX’s /etc/ntp.keys file to your client computer,
use the secure copy utility
scp
, or you can just use a text editor on your client computer to create an
equivalent file.
IMPORTANT
Handling of the
/etc/ntp.keys
file is the weak link in the MD5 authentication scheme. It is very impor-
tant that it is owned by root and not readable by anyone other than root .
After transferring the file by
ftp
, and placing it in the
/etc
directory on the client computer, issue
these two commands at the shell prompt:
chown root.root /etc/ntp.keys
chmod 600 /etc/ntp.keys
Configure NTP
You must edit the ntp.conf file which
ntpd
, the NTP daemon, looks for by default in the /etc directo-
ry. Assuming that you have created two trusted keys as shown in the example in the previous chapter,
add these lines to the end of the ntp.conf file:
keys /etc/ntp.keys
trustedkey 1 2
Modify the line added previously in
Basic NTP Client Setup
so that authentication will be used with
the Tempus LX server using one of the trusted keys, in this case key # 1:
server 192.168.1.245 key 1
Re-start
ntpd
to have it begin using the Tempus LX server with MD5 authentication. Use the NTP
utility
ntpq
to check that
ntpd
is able to communicate with the Tempus LX. After issuing the com-
mand
ntpq
you will see the
ntpq
command prompt:
ntpq>
Use the command
peers
to display the NTP peers which your computer is using. One of them should be the Tempus LX
server which you have just configured. You should verify that it is being ‘reached’. (You may have
to continue issuing the peers command for a minute or two before you will see the ‘reach’ count
increment.)