S o n o m a U s e r M a n u a l
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C H A P T E R T H R E E
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S o n o m a U s e r M a n u a l
N E T W O R K T I M E P R O T O C O L ( N T P )
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 le 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 le 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 Configuring the NTP Server Using
the Network Interface or Serial Port above, add these lines to the end of the ntp.conf le:
keys /etc/ntp.keys
trustedkey 1 2
Modify the line added previously in Unix-like Platforms: Basic NTP Client Setup so that authenti-
cation will be used with the Sonoma server using one of the trusted keys, in this example, key # 1:
server 192.168.1.120 key 1
Restart ntpd to have it begin using the Sonoma server with MD5 authentication. Use the NTP utility
ntpq to check that ntpd is able to communicate with the Sonoma. After issuing the command
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 Sonoma server
which you have just congured. You should verify that it is being ‘reached’. (You may have to con-
tinue issuing the peers command for a minute or two before you will see the ‘reach’ count increment.)
You can verify that authentication is being used by issuing the command
associations
to display the characteristics of the client server associations. In the “auth” column of the display,
you should see “OK” for the row corresponding to the Sonoma server. If you see “bad”, you should
wait a few minutes to be sure that there is a problem since “bad” is the initial state of this setting. If
the “bad” indication persists then you must check your conguration for errors. Typically this is due
to a typing error in creating the /etc/ntp.keys le on the client that causes a mismatch between the
keys being used by the server and client. (If you transfer the le by ftp or scp, this shouldn’t be a
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