A lot of companies are unsure which solution to choose and many may not be aware of Docker Swarm as an alternative to Kubernetes. One thing that many Sysadmins find is that Docker Swarm is simply easier, quicker to setup and maintain by far than Kubernetes.........

The Best Docker Tutorial for Beginners We quickly explain the basic Docker concepts and show you how to do the most common tasks from starting your first container, to making custom images, a Docker Swarm Cluster Tutorial, docker compose and Docker buildfiles.........

1. Let's work from an environment where we can install Ansible on. If you are using an older version of Linux based on Mint 18 or Ubuntu 16, you may want to get the PPA and get the latest version of Ansible that way: sudo apt install gpg sudo add-apt-repository ppa:ansible/ansible sudo apt update........

A lot of older devices either support telnet or very old SSH keyx algorithms which are insecure and disabled by all newer/modern SSH clients for security reasons. However, sometimes you may be on a LAN via VPNor some other secured network or for whatever reason, absolutely, need to connect to this device and sometimes old/embedded devices may not be possible to update to a newer SSH server. If you run into this you may be using a modern/newer SSH client and get thi........

Enable "cli" mode equivalent in JunOS cli Configure Mode configure So rather than going to the console on a Cisco switch and typing "enable" and then "conf t", the equivalent in JunOS is "cli" and "configure". How Do You Apply Changes You've Made? You can make all kinds of changes to the switch, but remember they are not........

This tutorial will get your router up and running using emulation tools. In this case we'll be getting a Cisco C7206 (C7200 series) VXR router going which also supports SCCP VOIP services. dynamips is the emulator itself and dynagen is the front-end tool that helps us control everything. It is used by tools such as gns3 and eve-ng. Together the two tools (dynamips and dynagen) allow us to create and emulate REAL router........

This is caused because the user is running as qemu for virt-resize and if qemu does not have privileges to read from the source and write to the destination, it will fail with the below. So either change the uid of qemu or change the ownership of the source and target. Solution: export LIBGUESTFS_BACKEND=direct virt-resize --expand /dev/sda2 /root/kvmtemplates/windows2019-eval-template.img /root/kvmguests/kvmkvmuser4515........

This should work but the key thing is having the "-cpu host" flag. Once you add the correct -cpu host flag then it should boot just fine on KVM. qemu-system-x86_64 --enable-kvm -cpu host -smp 8 -m 8192 -drive format=raw,file=the-file.img Examples can be found here on how to boot Windows properly with KVM.........

I find that the default settings for the radeon driver that is applied to most AMD cards is horrible. For example by default TearFree is not enabled and it causes videos to have some kind of square artifacts. Here are the settings I have found most suitable for AMD cards: You need to create file in the following path and restart Xorg or your computer to apply it: *Beware that making a mistake here will possibly make your computer........

This is all controlled by /etc/issue You can basically enter anything in there that you like, but there are preset variables that are mentioned at the end of the page that discuss this. Some examples of /etc/issue: Centos 7: S Kernel r on an m Ubuntu 16.04: Ubuntu 16.04.6 LTS n l You can also insert any of t........

In most of the Cisco router IOS I find the ports like ge0/0 ge0/1 and ge0/2 or whatever your ports are down. They will not even give you a link light. So one of the first tasks should be getting the port you are working with up. In my case the first goal is often connectivity with the LAN and WAN. LAN = your local area network (eg. in the office/home ) WAN= your ISP/public internet (eg. fiber/cable/dsl/ethernet).........

Cisco's CUCM (Cisco Unified Communication Manager) is a system that combines voice, video, data and mobile products into a single unified management suite. At its core, the CUCMis like a "Super PBX" that controls the flow of all communications through an organization even single or multiple site deployments. Cisco's CUCMmakes communication more effective and simple through centralized management and unification of communications resources.........

zenity is a nice utility as part of the gnome window manager that allows you to script from bash and retrieve the input from the user. It could also be helpful in just notifying a user when they login with a popup window. I'll give an overview of what's available with zenity: Application Options: --calendar Display calendar dialog --entry Display tex........

iptables allow port 22 example Of course change --dport and -s to suit your needs #allow certain IP to access port 22 iptables -A INPUT -p tcp -m tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT # block others iptables -A INPUT -p tcp --dport 22 -j DROP........

The reason for this article is because a lot of us don't physically see our hard drives they are often remote in a datacenter etc and the actual serial number we see in SMART is not enough to check for some manufacturers. A good example is our first one the Toshiba === START OF INFORMATION SECTION === Device Model: TOSHIBA DT01ACA200 Serial Number: 33FMDW4AS........

A simple way that may work for a lot of people who just need basic output for their scripts or daemons to announce an action is this: echo "body or message" | mail -s "realtechtalk.com" user@domain.com If you want to send a text file as the body just do this instead: mail -s "realtechtalk.com" user@domain.com < /tmp/sometxtfile.txt These are some ve........

So I have a domain "testdomain.com". Inside test domain.com's root is the following .htaccess: Options +FollowSymLinks -Indexes ErrorDocument 403 /launch/index.html Order Deny,Allow Deny From All Allow From 192.168.1.2 When you visit anything other than root things work fine. Eg. if you visit http://testdomain.com/somedirfile.html It will show the right error in /launch/........

I'm having trouble making it work on very shaky video the result seems kind of warped/blurry/fish eye like and not as good as some other examples I've seen: ffmpeg -i MVI_1285.MOV -vf vidstabdetect=shakiness=10:accuracy=15 -f null MVI_1285.trf ffmpeg -i MVI_1285.MOV -vf vidstabtransform=smoothing=30:input="transforms.trf" MVI_1285.MOV.mp4 I've played around with the shakiness, accuracy etc.. but not the smoothing part.........

# yum -y install qemu-kvm Loaded plugins: fastestmirror Setting up Install Process Loading mirror speeds from cached hostfile * base: mirror.lzu.edu.cn * elrepo: ftp.utexas.edu * epel: ftp.jaist.ac.jp * extras: mirrors.aliyun.com * openvz-kernel-rhel6: mirror.fdcservers.net * openvz-utils: mirror.fdcservers.net * updates: mirrors.nwsuaf.edu.cn Resolving Dependencies........

iptables -t nat -A OUTPUT -m addrtype --src-type LOCAL --dst-type LOCAL -p tcp --dport 3306 -j DNAT --to-destination ip.ip.ip.ip iptables -t nat -A POSTROUTING -m addrtype --src-type LOCAL --dst-type UNICAST -j MASQUERADE sysctl -w net.ipv4.conf.all.route_localnet=1 Make sure you substitute "ip.ip.ip.ip" for your real public IP and also the "--dport 3306" for the port you want to forward. Finally run the sysctl command and........

Based on this from Debian The 'distribution' can be either the release code name / alias (wheezy, jessie, stretch, sid) or the release class (........

libguestfs tools howto guide for managing virtual machine images. libguestfs-tools aka guestfs tools has a lot of tools that make this very easy for you. You can easily mount partitons from an image with some of the commands below. To mount a partition #mount the kvmuser102821.img image and the /dev/sda1 partition from it to the local directory "mount" guestmount -a kvmuser102821.img -m /dev/sda1 mount ........

First of all if you're getting this error it is a result of extreme database activity. If you aren't expecting it or it doesn't make sense to you 99% of the time this is a database driven script being exploited (some common examples I see often are things like phpBB being hit by dozens, hundreds or thousands of bots making constant DB write requests). The easiest way to identify this is to restart MySQL and then run the third party tool "mtop" and you'll see all........

I struggled with this for awhile because sometimes you have rewritten URLs that you want to pass a query string but most of the info and examples do not support this. Take a typical example like this: RewriteRule ^(.*)-(.*)-(.*) /?module=$3&id=$2 You need to add the QSA flag to make it work like below: RewriteRule ^(.*)-(.*)-(.*) /?module=$3&id=$2 [QSA] The QSA preserves the original query string but also appends it wit........

drbd 8.3 hard drive failure recovery drbdadm attach r0 DRBD module version: 8.3.10 userland version: 8.3.8 you should upgrade your drbd tools! 0: Failure: (119) No valid meta-data signature found. ==> Use 'drbdadm create-md res' to initialize meta-data area. ........

template=$(cat ........

table.custom { border-collapse: collapse; border-style: solid; border-width: 1px; border-color: black; font-size: 11px; } table.custom td { border-collapse: collapse; border-style: solid; border-color: black; &........

mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3 cat /proc/mdstat Personalities : [raid1] md2 : active raid1 sdb3[1] sda3[0] 1363020736 blocks super 1.2 [2/2] [UU] [=>...................] resync = 8.3% (113597440/1363020736) finish=276.2min speed=75366K/sec ........

for entity in {1..20}; do echo "entity=entity" done The above will loop 20 times, you could also do {2..50} etc... for entity in {0..10..5}; do echo "entity=entity" done The above will loop 10 times but will start from 0 and increment by 5 each time.........

I've read some people/sources say "the timing must match or it won't work". This is not true at least for the Supermicro boards I've tested this on. Some examples: PC2-5300F-555-12 PC2-5300F-555-11 etc.. Notice the "12" and "11" Also the ones that have a "PC2-5300F-555-11-B0" or "PC2-5300-555-11-D0" are also fine. What happens is what one would expect, the........

I backed up everything in the /mnt/sd_card directory thinking that some dataloss could occur for some reason but purposely left my microSDHC unbacked up thinking that "it won't touch that since it's external" and Samsung's and other manufacturers website even say this (that it won't be affected and not to worry etc). Apparently I was wrong, my microSD was "undetected" and asked to be formatted after the upgrade (there goes 3-months worth of family photos). No........

There are all kinds of threads and links on the internet, and this seems to be a contentious issue butI don't know why. 95th percentile is either a good deal for some or a big rip off for others, Ijust said it there :) But the reality is that for MOST people who transfer low amounts of data but burst to higher speeds such as 40mbit+ even for short periods of time, then you'll pay a lot of money to do that. Basically 95th percentile is an-old archaic method........

ls ls: error while loading shared libraries: libtermcap.so.2: cannot open shared object file: No such file or directory This is not an ldd problem or case of anything missing, this only happened after I upradedUbuntu. declare -x PATH="/home/user/bin:/usr/local/bin:/usr/bin:/bin:/usr/games" "/home/user/bin" is the problem! It's weird because I have no idea how it happened.........

understanding /etc/aliases *remember to apply changes you need to run "newaliases" after editing /etc/aliases one thing I don't get is that it doesn't allow you to specify the whole e-mail address on the left-hand side eg: yourfullemail@domain.com: someotheremail@domain.com postalias: warning: /etc/aliases, line 109: name must be local (if you try the above) It works more like this: your........

Webmin Setup Centos 5: wget http://downloads.sourceforge.net/project/webadmin/webmin/1.530/webmin-1.530-1.noarch.rpm?r=http%3A%2F%2Fwww.webmin.com%2Fstandard.html&ts=1294339690&use_mirror=surfnet [1] 24229 [2] 24230 [root@host ~]# --2011-01-06 21:48:20-- http://downloads.sourceforge.net/project/webadmin/webmin/1.530/webmin-1.530-1.noarch.rpm?r=http%3A%2F%2Fwww.webmin.com%2Fstandard.html Resolving downloads.sourceforge.net... 216.34.181.........

This is a great way to use your ftp server space, for example on your web hosting account (althoughI believe many hosts don't allow storage like this), but if you have a VPS/Dedicated Server etc.., this would be perfect. Imagine how easy it is to work with an ftp account that you can just mount as a normal partition or directory in Linux, it would be great for backups etc.. Name curlftpfs - mount a ftp host as a local directory Synopsis........

I'm using Ubuntu 8.04 but anyone using older kernels will find this may apply to them. My Intel graphics are very slow with the default Xorg settings but by using "EXA" acceleration, scrolling down windows of text becomes pretty snappy. Just edit /etc/X11/xorg.conf Section "Device" Identifier "Configured Video Device" &nb........

It's basically free bash shell script available from: http://wpkg.org/email2fax/index.php/Main_Page Make sure you have the required tools: libtiff ghostscript mpack/munpack Where you can e-mail your Asterisk box and it will fax it to the phone number in the subject line. The good news ends there, it is fairly undocumented and buggy. Take for example how the documentation mentions you can invoke from the com........

Nice General Linux RAID 1 GuideFull examples/tutorials that should work for any Linux system using GRUB or LILO as the boot loader. This is the only tutorial I've seen that clearly shows how you can convert an existing non-RAID system to software RAID1 remotely, without ever having to be at the computer. This is important for people who co-locate or rent dedicated servers that they may not have physical access to in a timely manner. https://alioth.debia........

Heredoc warningsExample $somevariable = ........

Upgrade Release Kernel TipsThis is for CentOS 3.1 to 3.8 but the methodology will apply everywhere. I ran into a problem first of all with a non-booting system after running #yum update centos-release It took me to 3.8 and upgraded all the other packages [b:7e931c835d]BUT[/b:7e931c835d] because of some stupid flags enabled in /etc/yum.conf the KERNEL WASN'T UPGRADED SO AFTER BOOTING, WELL IT DIDN'T BOOT OF COURSE :) H........

Crontab Tutorial - Tips & Shortcuts*/5 * * * * /command The above is an example of a command that runs every 5 minutes. Normally instead if the "*/5" you'd have to type "5,10,15,20,25,30,35,40,45,50,55" etc... You can use it to run a program every 5 days, 5 months 5 years etc...Crontab run one a day at a certain time[code:1:7a3bd32dfa]0 1 * * * /home/backupguy/databackup.sh[/code:1:7a3bd32dfa]........

Helpful IPFW ExamplesSomeone's real life examples: http://lists.freebsd.org/pipermail/freebsd-security/2004-July/002181.html Or you can try the FreeBSD Handbook guide: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/firewalls-ipfw.html........

CVSUp the Easy WayIf you're reading this you probably have never used CVSUp or don't know how. CVSUp can be used for two things or just one if you prefer. *Keeping your kernel up to date *Keeping your port list up to date Start by editing the following file in: [b:76928b387d]vi /usr/share/examples/cvsup/cvs-upfile[/b:76928b387d] It can be quite overwhelming with all the crazy options. Basically there are only 3........

I've tried to find a good sensible solution to cluster with and each technology has it's pros and cons and there is no perfect solution and I've found a lot of "exaggerations" in the applications, benefits and performance of these different filesystems. DRBD I first started off with DRBD and Ihave to say it does live up to the hype, is quite reliable (although it can be annoying to match up the kernel module and user applications since they must match and whe........

In those 4 simple commands you can setup mutual key exchange between two sshservers by using a single login shell session and single window. *Just change the IP address examples of (10.10.0.2) to the target of your mutual key exchange. It doesn't matter if the server is on a LANor WAN(well unless the server is behind a firewall and you cannot SSHinto it).........

It's actually very simple and "grep" makes it as easy as possible. I'll outline a few common scenarios and provide some examples. Say you want to search ALLfiles within the current directory (and inside/deeper) for the text "phpinfo()" grep -R "phpinfo()" * If you want to search only certain files such as only .txt you would do this instead: grep -R "phpinfo()" *.txt As you ca........

As much of a computer nerd as Iam, I'm usually a late adopter to technology for a few reasons. Ifeel most new hyped technologies and electronics are mainly fads, and I'm also cheap. Adopting later means you avoid the bugs, kinks and most importantly pay the lowest price, that's me being cheap again :) I never read much about the iPhone but Isaw all the hype around it and until recently I wasn't a big fan of anything Apple until a few years ago I realize........