Thomas,
try...
(from the command line, type the following--all on one line)
echo 'net.ipv4.icmp_echo_ignore_all = 1' > /etc/e-smith/templates/etc/sysctl.conf/net.ipv4.icmp_echo_ignore_all
then...
/etc/sbin/expand-template /etc/sysctl.conf
and probably (shouldn't hurt anything--I think)...
/sbin/e-smith/signal-event bootstrap-console-save
and definitely...
service network restart
NOTE:
The file is built from the templates in the alphabetical order of the filenames, so the parameter should appear in the following order...
...
net.ipv4.conf.default.rp_filter = 1
net.ipv4.icmp_echo_ignore_all = 1
net.ipv4.ip_dynaddr = 1
...
Hasan