Prevent ssh timeouts

Locally add the following to ~/.ssh/config
ServerAliveInterval 120 # null packet every 120 seconds
On the server side add the following:
ClientAliveInterval 120 # null packet every 120 seconds
ClientAliveCountMax 720 # 24hs

fail2ban unban ip

To search all the ips that were banned we enter interactive mode:

$ fail2ban-client -i
Then we check a jail status, for example sshd: > status sshd the output: Status for the jail: sshd |- Filter |  |- Currently failed:0 |  |- Total failed:27 |  `- File list:/var/log/auth.log `- Actions    |- Currently banned:37    |- Total banned:38    `- Banned IP list:<a big list of banned ips>
So, if we want to unban a particular ip address, let's say X Then, we execute: > set ssh unbanip (within interactive mode)

Lastly, if you want to execute it directly from command line:

$ fail2ban-client get <JAIL> actionunban <IP-ADDRESS>
That's all.

Cleaning Bash History...

Just run:
cat /dev/null >~/.bash_history && history -c && exit

The document "mydoc" could not be saved. You don’t have permission

Just run the following command:
$ chmod -R -N mydoc

*** System Restart Required *** - Ubuntu

Which packages need a system reboot?

Just check /var/run/reboot-required.pkgs

Install memcached in Mac OS El Capitan

The easiest way to install memcached is to use homebrew package installer:

$ brew install memcached

This locates memcached in /usr/local/opt/memcached/bin/

Starting memcached (by default at port 11211 or with -p port_number):

$ memcached -p 9000

To have launchd start memcached now and restart at login:

$ brew services start memcached

To change the default ram size (64mb) used by memcached use -m option:
$ memcached -m 128  -p 9000

Lastly, run memcached as a daemon with -d:

$ memcached -d -p 9000