[GTALUG] Ubuntu -- Disabling Ping

[Jamon Camisso]

On 29/08/18 21:44, Howard Gibson via talk wrote:
>    I am playing with my hack Ubuntu machine, and I am sorting out
> security. I want to disable ping.  This is a laptop, and I want to
> document the application of aluminium foil.
> 
>    The standard ping disabler is the following line...
> 
> # echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
> 
>    This works fine on my Fedora laptop.  On Ubuntu, I get...

The # makes me think you are root on the Fedora laptop.

> $ sudo echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all
> -bash: /proc/sys/net/ipv4/icmp_echo_ignore_all: Permission denied

That's expected with a sudo echo > redirect invocation. The shell is
doing redirection. sudo is invoking echo, the output of which is being
redirected in your normal user's shell to a file that you do not have
permission to write to.

Try this if you want to go the sudo route:

echo 1 |sudo tee /proc/sys/net/ipv4/icmp_echo_ignore_all

That way tee is invoked with elevated privileges and writes its output
to the file.

Or you can become root like on your Fedora system and use echo 1 >...

Cheers, Jamon