Dear all

Posted on in Categories Linux News last updated January 30, 2017

Do you find my tutorials and nixcraft ( https://www.cyberciti.biz/ ) site useful? Please consider supporting it especially if you use ad-blocker. It is hard to keep the site running when so many people block ads. nixCraft is a single man indie operation and online since 2002. I had started this site for sharing my knowledge and documenting my experience as a sysadmin. Over last 15 years site grown a lot. I was able to fund nixCraft for a while with my job and savings.

I have written about Linux, Unix, FreeBSD, OpenBSD, Sysadmin and FOSS-related tutorials for many years. I have written over 5100+ tutorials and long blog posts. Apart from posts, I regularly reply tech support emails and moderate comments here. nixCraft has become a 40+ hour/week job for me. I want to nixCraft to grown more for a long time. It is time to see if it is possible to be a self-employed writer in the open source and Linux. By supporting me, you are going to keep the www.cyberciti.biz website alive.

You can choose from several options to support nixCraft:

  1. Patreon (Recommended option and you can pledge any amount you want from $1 to $as_per_your_wish)
  2. PayPal (one time donation)
  3. Bitcoin address: 1F8jsWqRuhND7LgmJ9F7QzwPBp4PS2tkRR

I am sure most *nix sysadmins or Linux user were helped at least once or many times by my nixCraft (https://www.cyberciti.biz). I needs your support, too. Thanks for any help you can offer if you decide to, and thanks for being a reader!

Download Free eBook PDF: The Awk Programming Language

Posted on in Categories Link last updated January 23, 2017

AWK is a programming language designed for text processing and typically used for a data extraction and reporting tool. It is a standard feature of Linux, FreeBSD, OpenBSD, MacOS and most Unix-like systems.

The Awk Programming Language
The Awk Programming Language

This is one of my favorite books. It is a superb book if you are looking to learn about AWK. AWK is very fast when it comes to data processing. I highly recommend this classic book to all Unix fans.

Download The Awk Programming Language Book PDF Version {11.7 MB} or use wget command as follows:
$ wget https://archive.org/download/pdfy-MgN0H1joIoDVoIC7/The_AWK_Programming_Language.pdf
Sample outputs:

--2017-01-23 10:17:18--  https://archive.org/download/pdfy-MgN0H1joIoDVoIC7/The_AWK_Programming_Language.pdf
Resolving archive.org (archive.org)... 207.241.224.2
Connecting to archive.org (archive.org)|207.241.224.2|:443... connected.
HTTP request sent, awaiting response... 302 Moved Temporarily
Location: https://ia802309.us.archive.org/25/items/pdfy-MgN0H1joIoDVoIC7/The_AWK_Programming_Language.pdf [following]
--2017-01-23 10:17:19--  https://ia802309.us.archive.org/25/items/pdfy-MgN0H1joIoDVoIC7/The_AWK_Programming_Language.pdf
Resolving ia802309.us.archive.org (ia802309.us.archive.org)... 207.241.228.49
Connecting to ia802309.us.archive.org (ia802309.us.archive.org)|207.241.228.49|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 8204128 (7.8M) [application/pdf]
Saving to: 'The_AWK_Programming_Language.pdf'

The_AWK_Programming_Language.pdf            100%[========================================================================================>]   7.82M  11.7MB/s    in 0.7s    

2017-01-23 10:17:20 (11.7 MB/s) - 'The_AWK_Programming_Language.pdf' saved [8204128/8204128]

9 Awesome Open Source Web Performance Software For Linux and Unix-like Systems

Posted on in Categories Open Source last updated May 7, 2017

Web performance is nothing but the speed in which web pages are downloaded and displayed on the user’s web browser. Faster website speeds have been shown to increase sales or increase visitor loyalty including user satisfaction. Particularly useful for those use slow internet connections or on mobile phones/tablets. You can increase the speed of page load using:

  1. Server side cache
  2. Browser side cache
  3. Faster disks
  4. Image optimization
  5. Web application accelerator focusing on optimizing caching and compression
  6. Load balancing and SSL offloading
  7. Geo or DNS-based load balancing and more.

In short, one can increase the time it takes for pages to render using multi-layered cache and asynchronous communication with server-side components. In this post, I will list my favorite open source software based TCP/HTTP load balancer and proxying solution for web performance.

Patch your FreeBSD server for openssh vulnerabilities [11/Jan/2017]

Posted on in Categories Link last updated January 11, 2017

OpenSSH is critical for both sysadmin and programmers. It is an implementation of the SSH protocol suite, from OpenBSD project. It provides an encrypted session to your server.

OpenSSH multiple vulnerabilities

OpenSSH has multiple vulnerabilities as of 11th January 2017 running on FreeBSD operating system. From the advisory:

The ssh-agent(1) agent supports loading a PKCS#11 module from outside a trusted whitelist. An attacker can request loading of a PKCS#11 module across forwarded agent-socket. [CVE-2016-10009]

When privilege separation is disabled, forwarded Unix domain sockets would be created by sshd(8) with the privileges of ‘root’ instead of the authenticated user. [CVE-2016-10010]

Solution

I updated my vulnerable FreeBSD box via a binary patch:
# freebsd-update fetch
# freebsd-update install
# service sshd restart
# ps aux | grep -i ssh-agent

If found any ssh-agent process, kill all running ssh-agent:
# killall ssh-agent

Fig.01: Fixed FreeBSD-SA-17:01.openssh
Fig.01: Fixed FreeBSD-SA-17:01.openssh

For more info see FreeBSD security mailing list.

How to speeding up SSH session creation

Posted on in Categories Link last updated January 11, 2017

You can reuse OpenSSH connections to the same server when you want to open subsequent connections to the same server. For example, if I ran ssh [email protected], the ssh client will establish a new SSH connection. It usually takes only a few seconds. However, if I run ssh [email protected] command again, connecting to a server42.cyberciti.biz multiple times result into the overhead.

This tutorial talks about ssh features called multiplexing that reuse an already-established connection when creating a new SSH session.