Sysdig

Sysdig is open source, system-level exploration: capture system state and activity from a running Linux instance, then save, filter and analyze. Sysdig is scriptable in Lua and includes a command line interface and a powerful interactive UI, csysdig, that runs in your terminal. Think of sysdig as strace + tcpdump + htop + iftop + lsof + awesome sauce.
With state of the art container visibility on top.

http://www.sysdig.org/

How To Verify SSL Certificate From A Shell Prompt

How do I verify and diagnosis SSL certification installation from a Linux / UNIX shell prompt? How do I validate SSL Certificate installation and save hours of troubleshooting headaches without using a browser? How do I confirm I’ve the correct and working SSL certificates?

http://www.cyberciti.biz/faq/test-ssl-certificates-diagnosis-ssl-certificate/

Nginx Error_log Configuration

Nginx serves millions of applications on a daily basis, and those millions of apps generate errors. Guess what? So do yours. Some of them are critical, while others are just notices. The important thing here is to get access to those errors to debug and have a clear view of what’s happening with your web applications.

In this article, you will explore the Nginx error_log configuration and how Nginx handles the types of errors that can be logged into the files.

http://www.nginxtips.com/nginx-error_log-configuration/

Duplicati Backup Software

Duplicati is a backup client that securely stores encrypted, incremental, compressed backups on cloud storage services and remote file servers. It works with Amazon S3, Windows Live SkyDrive, Google Drive (Google Docs), Rackspace Cloud Files or WebDAV, SSH, FTP (and many more). Duplicati is open source and free.

Duplicati has built-in AES-256 encryption and backups can be signed using GNU Privacy Guard. A built-in scheduler makes sure that backups are always up-to-date. Last but not least, Duplicati provides various options and tweaks like filters, deletion rules, transfer and bandwidth options to run backups for specific purposes.

Reference and Download:
http://www.duplicati.com

Backup and Restore permissions in Linux

You can use getfacl and setfacl to take a backup of permissions from a directory and then restore those permissions back if required at a later date.

The following directory of /perms contains these permissions:

/perms/
|-- [-rw-r--r--] permfile1.txt
|-- [-rw-r--r--] permfile2.txt
|-- [drwxr-xr-x] subperm1
| |-- [-rwxr-xr-x] permfile1.txt
| `-- [-rw-r--r--] permfile2.txt
`-- [drwxr-xr-x] subperm2
|-- [-rw-r--r--] permfile1.txt
`-- [-rwxr-xr-x] permfile2.txt

To Backup this directory and sub-directory permissions you can run:

# getfacl -R /perms > perms_bu

The contents of the perms_bu file will contain all the permission details for both directories and files. Should any file or directory permissions be changed or modified in the future, we can restore as show below with the perms_bu file

To restore the permissions:

# setfacl --restore=perms_bu

NOTE: When you restore the permissions be sure you are in the relevant path area e.g. for the above example run the restore from the root area /

Reference:
Linux Man pages or http://linux.die.net/man/1/getfacl