[ubuntu] Martian Source Flodding Syslog

I'm ruing Ubuntu server 14.04 and I'd like to stop logging martian source messages as they are flodding the syslog, but the settings I've tried have no impact and leave the logging intact:

rc.local:
/bin/echo "0" > /proc/sys/net/ipv4/conf/all/log_martians

No chnage to the logfile.

and in sysctl.conf:
net.ipv4.conf.all.log_martians = 0
net.ipv4.conf.default.log_martians = 0

No change to the logfile.
Martian source messages are from network devices searching for a printer which is tued off 99% of the time.