[pkg-ntp-maintainers] Should I worry about "ntpd[2994]: receive: Unexpected origin timestamp from" messages

[Agustin Martin]

Hi, ntp maintainers,

I am seeing a number of messages like

ntpd[2866]: receive: Unexpected origin timestamp from 176.31.53.99

in my syslog.

According to http://www.cs.bu.edu/~goldbe/NTPattack.html this might be an
indication of a so called 'priming-the-pump' attack, but it suggests to
upgrade to ntpd v4.2.8p4. However, I already have Debian 1:4.2.8p4+dfsg-3
installed.

176.31.53.99 seems to be be current IP of 2.es.pool.Ntp.org

Should I worry about those messages?

Thanks in advance,

-- 
Agustin