Secure shared memory

In my Ubuntu deployment script I have written a function to secure shared memory. For a web server it's important to secure the shared memory to tighten up security. Below you can find the code:

echo "tmpfs       /dev/shm     tmpfs   tdefaults,noexec,nosuid        0 0" >> /etc/fstab

When I reboot the web server it gets stuck. I can't see where it goes wrong. Do you have an idea, please let me know.

Unless theres's a typo in your question, I think you're options are off. First, don't specify 'defaults' (or tdefaults, as you have it.. Here's the output of my shm directory taken from cat /proc/mounts:

none /run/shm tmpfs rw,nosuid,nodev,relatime 0 0

Note that on my ubuntu (12.10) it is mounted in /run and not /dev, although I doubt that matters. Try changing your string to

echo "tmpfs /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0" >> /etc/fstab

and see what happens.

I think the /dev/shm matters. I have had problems mounting /dev/shm on 14.04 (Trusty) with noexec. Using /run/shm works flawlessly. e.g.

none    /run/shm        tmpfs   rw,nodev,nosuid,noexec  0       0