Ok so now I have a new problem. When I run the code (using the bash -x option ) ...
# Enable broadcast echo Protection
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
I get the response
:No such file or directoryet/ipv4/icmp_echo_ignore_broadcasts
Now we can see that the error message "No such file or directory" is being merged with the pathname "/proc/sys/net/ipv4/icmp_echo_ignore_broadcasts". I've highlighted them in color.
The pathname is definitely valid. I think Fedora is trying to expand it out somehow.