• Cisco CME and C7200 Router Testing and Learning Environment on Ubuntu 20+ Setup Tutorial Guide


    Since newer versions of Ubuntu like 20, you will find there is no longer dynagen and that the dynamips provided is faulty and will segfault each time: Cisco Router Simulation Platform (version 0.2.14-amd64/Linux stable) Copyright (c) 2005-2011 Christophe Fillot. Build date: Apr 3 2018 12:20:29 Local UUID: 3c1c0b7f-2fab-4fda-b40b-74841d1bcfe0 Instance ID set to 1. netio_tap_create: unable to open TAP device tap1 (No such fi........
  • How to Install Any OS on a Physical Drive from Windows Using VMware Workstation (Linux, Windows, BSD)


    Uses: Install OS on physical drive Linux installation VMware Install Windows on physical drive Boot OS from physical drive VMware Workstation tutorial Linux virtual machine to physical disk Windows to Linux migration Dual boot OS installation Boot from external SSD Linux, Windows, BSD installation guide Physical drive boot OS........
  • Dell Server Workstation iDRAC Dead after Firmware Update Solution R720, R320, R730


    This is certainly a poor design, as you can read many seasoned admins who have updated their iDRAC only to have it killed. One possible cause is not by doing all the incremental updates, doing updates from an old iDRAC to one many revisions newer is a sure way to kill things, but even then there is no guarantee based on the amount of failures. List of threads of people's dead iDRAC's:........
  • Cloned VM/Server/Computer in Linux won't boot and goes to initramfs busybox Solution


    This is mainly for if you've done something silly like trying to clone a Live, running VM image. In this example, the VM initially finds grub and tries to boot but is kicked straight into initramfs rescue mode/busybox right after this. If you've done this "silly" thing, you could have dataloss but a lot of times just using fsck will fix it as you are guaranteed at best to have some corruption and inconsistencies in the filesystem. My theory is that some files wer........
  • Linux Debian Mint Ubuntu Bridge br0 gets random IP


    This can break things easily in remove environments where it was normally easy to convert a normal eth0 to a bridge under br0, and that bridge would normally have the same MAC address by default, which is desirable for most situations. In Debian 11 this is different for some reason now. https://unix.stackexchange.com/questions/681013/bridge-gets-random-mac-........
  • redis requirements


    sysctl vm.overcommit_memory=1 echo never > /sys/kernel/mm/transparent_hugepage/enabled echo 511 > /proc/sys/net/core/somaxconn 1:M 26 Nov 2023 21:34:33.840 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128. 1:M 26 Nov 2023 21:34:33.840 # Server initialized 1:M 26 Nov 2023 21:34:33.840 # WARNING overcommit_memory is set to 0! Background sa........
  • How to kill a docker swarm


    Assign way more replicas than you have of memory on all nodes and watch the Swarm crash which can easily reproduce in a small VMfor testing. root@Deb11Docker01:~# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAM........
  • docker swarm silly issues


    The error below can be caused by a gateway that is unpingable: docker swarm join --token SWMTKN-1-1kogg8da68gtb1j7ezaddowyy9s0an5s9tue758o20k18liskw-5h3f61hrrmv3u6agshvbtcklf 172.16.1.80:2377 Error response from daemon: manager stopped: can't initialize raft node: rpc error: code = Unknown desc = could not connect to prospective new cluster member using its advertised address: rpc error: code = DeadlineExceeded desc = context deadline exceeded........
  • isc-dhcp-server dhcpd how to get longer lease


    You can do a static lease that is tied to the MAC address but what a lot of users prefer is that they come into the office or lab the next day and that their device gets assigned the same IP address (if possible). As we can see in the dhcpd logs that there is threshold that is defaulted as we'll show later. Whatever the threshold is set at, if the lease is younger than the threshold, it will keep the same lease. In other words, if the device goes to sleep or is powered off........
  • docker error not supported as upperdir failed to start daemon: error initializing graphdriver: driver not supported


    Nov 15 17:00:49 rttbox kernel: overlayfs: filesystem on '/var/lib/docker/overlay2/check-overlayfs-support450709549/upper' not supported as upperdir Nov 15 17:00:49 rttbox dockerd[93755]: failed to start daemon: error initializing graphdriver: driver not supported The above error is often/normally caused because you are trying to run docker out of an unsuitable directory/filesystem. For example if you try to place docker's data inside an existing overl........
  • qemu-system-x86_64: Initialization of device ide-hd failed: Failed to get


    You start a qemu like this and another VM already started with the same .iso qemu-system-x86_64 -enable-kvm -m 4096 -cdrom some.iso But you get this error: qemu-system-x86_64: Initialization of device ide-hd failed: Failed to get "write" lock Is another process using the image [some.iso]? It's odd because the -cdrom by default is read-only and qemu should not want or care about getting write lock on........
  • File "/usr/local/lib/python3.5/dist-packages/pip/_internal/utils/entrypoints.py", line 12 f"pip{sys.version_info.major}", ^ SyntaxError: invalid syntax python pip3 error solution


    Is python3-pip pip3 not working anymore? Traceback (most recent call last): File "/usr/bin/pip3", line 11, in sys.exit(main()) File "/usr/local/lib/python3.5/dist-packages/pip/__init__.py", line 11, in main from pip._internal.utils.entrypoints import _wrapper File "/usr/local/lib/python3.5/dist-packages/pip/_interna........
  • Docker Swarm vs Kubernetes Comparison Guide


    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.........
  • Install Grafana on Linux Debian Ubuntu Tutorial Guide


    First we need a few extra packages: apt update apt install -y adduser libfontconfig1 musl sudo wget https://dl.grafana.com/enterprise/release/grafana-enterprise_10.3.1_amd64.deb Install / Enable Grafana dpkg -i grafana-enterprise_10.3.1_amd64.deb dpkg -i grafana-enterprise_10.3.1_amd64.deb (Reading database ... 44309 files and directories currently installed.) Preparin........
  • System has not been booted with systemd as init system (PID 1). Can't operate. Failed to talk to init daemon. Ubuntu Debian Linux Solution Cannot reboot


    You are probably using some custom image or maybe this is some sort of container that didn't boot with systemd. The solution is to use "reboot -f" reboot -f This will force the system/OS/VM/container to reboot.........
  • How To Upgrade Debian 8,9,10 to Debian 12 Bookworm


    Step 1.) Upgrade to Debian 11 first The process to go to Debian 12 is not as smooth as 11, when trying to upgrade from Debian 10. In fact, it doesn't work directly, so you'll first need to follow this guide to update to Debian 11, reboot and come back here if successful. Step 2.) Update sources.list Update your /etc/apt/sources.list like this: deb http://........
  • Docker dockerd swarm high CPU usage cause solution


    If you have swarm services and dockerd is creating a high load even with the containers just being idle, the easiest solution is to upgrade to a newer docker version. For example an identical config of 3 nodes, with Redis 5 with 30 replicas produces a load of about 1.45 in Debian 10 with Docker18.09.1 If I create the same setup on Debian 11, with Docker 20.10.5+dfsg1 then the CPU usage is low. One other difference I wondered is the kernel. In my test setup........
  • request_module: runaway loop modprobe binfmt-464c Kernel panic - not syncing: No init found Pid: 1, comm: swapper/0 Not tainted solution


    request_module: runaway loop modprobe binfmt-464c Kernel panic - not syncing: No init found Pid: 1, comm: swapper/0 Not tainted This is usually caused by a mismatch in architecture and happens frequently in development environments. Here is a example of what caused this issue: Your binaries are based on one architecture Your kernel was compiled with another architecture. Why does this happe........
  • How to upgrade to the latest Python version on Linux Ubuntu Debian Mint 3.11


    A lot of developers want to go to 3.11 because of the speed improvements, but most distros never have the latest Python version. Using the deadsnakes third party repo is the easiest way aside from compiling it yourself (which is safer and recommended): Step 1 - Add the repo apt-add-repository ppa:deadsnakes/ppa If you get an error about requests then install it:........
  • kernel panic initramfs not syncing cause solution


    Check your initramfs if it's missing /dev/null or /dev/console, this is likely the reason. If you want all actual devices to be created you could also enable devtmpfs in your kernel (.config) and mount like this during init: CONFIG_DEVTMPFS=y CONFIG_DEVTMPFS_MOUNT=y mount -t devtmpfs none /dev But note devtmpfs will not create /dev/null or /dev/console for........
  • python3 error Ubuntu Linux error solution SyntaxError: invalid syntax line 12 pip{sys.version_info.major}


    This sort of thing normally happens your python3 or pip3 has been updated, because you have to in order to use pip, but the newer pip now breaks compatibility with your old python (3.5 in this case). There are a few solutions, the easiest is perhaps to upgrade to a newer OS with a newer distro provided Python 3 or to manually install a newer version of Python/OR use a PPA like deadsnakes that provides newer versions. ........
  • How to install and configure haproxy on Linux Ubuntu Debian


    haproxy is one of the best known and widely used Open Source load balancers out there and a strong competitor to nginx. haproxy is used by many large sites per Wikipedia: HAProxy is used by a number of high-profile websites including GoDaddy, GitHub,........
  • talib/_ta_lib.c:747:10: fatal error: ta-lib/ta_defs.h: No such file or directory


    If you are installing ta-lib for Python and get this error then you can normally solve it by manually getting the ta-lib source files and compiling. tar -zxvf ta-lib-0.4.0-src.tar.gz cd ta-lib;./configure;make;make install Collecting ta-lib Downloading https://files.pythonhosted.org/packages/39/6f/6acaee2eac6afb2cc6a2adcb294080577f9983fbd2726395b9047c4e13ec/TA-Lib-0.4.26.tar.gz (272kB) &nbs........
  • How to install Windows or other OS and then bring to another computer by using a physical drive and Virtual Machine with QEMU


    This has been a tried and true method for Windows because it is finicky with hardware changes without a reinstall (eg BSOD on boot is what happens 9/10 times unless you move to the same hardwar). Surprisingly, if you use a QEMU VM and do a standard install, it has worked in every system I've thrown the drive in afterwards. So the play is this, use a USB SSD, physical SATA drive plugged internally or for convenience, you could use a SATA to USB adapter on another computer to perf........
  • vagrant install on Debian Mint Ubuntu Linux RHEL Quick Setup Guide Tutorial


    1 - Install Vagrant apt install vagrant Make sure you have a supported Virtualization tool like Virtualbox or VMWare, Hyper-V etc.. It automatically detects and uses what you have. Virtualbox has a lot of support here with tons of images. 2 - Init Vagrant We'll init to have a Debian 10 box by default to show how quick and easy it is. vagrant init generic/debian10........
  • RHEL 8 CentOS 8, Alma Linux 8, Rocky Linux 8 System Not Booting with RAID or on other servers/computers Solution for dracut and initramfs missing kernel modules


    This seems to have changed for RHEL 8 where a normal dracut to update your initramfs creates a system that only boots for the running kernel. For example if you have Kernel 5 and then chroot into a RHEL 8 variant which uses kernel 4.18, and run dracut, it seems that by default the system will be unbootable. It is also the case that if you move your RAID array or drives to another server that it will be unbootable, because dracut seems to only include modules needed for the curre........
  • debootstrap how to install Ubuntu, Mint, Debian install


    In this example we install debian 10 with --variant=minbase which gives us a minimal/tiny install. Don't use variant if you want the full size install. mkdir /tmp/deb10files debootstrap --variant=minbase buster /tmp/deb10files/ Did you get an error? debootstrap --variant=minbase buster /home/theuser/VMs/deb10files/ You'll get this error if you make a directory in your home........
  • Ubuntu Debian Mint Linux How To Update Initramfs Manually update-initramfs


    The easiest way for the current running kernel is: update-initramfs -u -k `uname -r` You could change -k to a specific kernel name if for some reason the current is not running (eg. if you are chrooted or in recovery mode). If you want to update all kernels then use "-k all" update-initramfs -k all -u update-initramfs: Generating /boot/initrd.img-5.4.0-162-generic........
  • grub blank screen how to manually boot kernel and initrd Linux Ubuntu Debian Centos won't boot solution


    You probably didn't do an "update-grub" and grub no longer has any proper menu entries, but before you can fix it let's try to get grub booting anyway. If you get this lovely black grub screen here's how you can get things booting. In my case I have a gpt partition with partition 1 and 2. Partion 1 is just my EFI / ESPand partion 2 /dev/sda2 is my root which includes /boot. You will have to adjust this if you had a separate /boot partition.........
  • Cisco Switch / Router How To Restore Factory Default Settings


    1.) Make sure your conf register is 0x2102 Do show version and at the very end of the output you will see the Configuration register. show version Configuration register is 0x2102 If the config register is not 0x2102 then enter this command: r1#configure terminal r1(config)#config-register 0x2102 r1(config)#end 2.) Let's Erase the NVRAM/flash........
  • Cisco 2900 3900 Router Password Reset How To Reset Enable Password


    It is a bit different and annoying here for these types of routers/models as you need to physically remove the CF (Compact Flash) and only then, will it enter ROMMON mode (Ctrl + Pause remotely over the console will not do it for us). This means you cannot do this remotely, or at least not without the help of a remote/physical helper. Step 1.) Power off, router and remove CF Disk Slot#2 Go to the router and remove the slot#2 cover uses your hand or it may help to use a........
  • CentOS 7 / 8 cannot boot with with mdadm RAID array solution


    This article about migrating to a CentOS 7 /8 RAID mdadm array has a lot of info but I wanted to focus specifically on what newer versions of CentOS 7 require to boot mdadm and what changes are necessary on CentOS 7.8+ CentOS 7 / 8 mdadm RAID booting requirements This assumes you are chrooting into an existing install or using it to get a new deployment ready. However, these steps can........
  • Loaded: masked (Reason: Unit hostapd.service is masked.) Solution in Linux Debian Mint Ubuntu


    If you are getting this error from systemctl "Loaded: masked (Reason: Unit hostapd.service is masked.)" we need to unmask the service. Solution systemctl unmask hostapd Removed /etc/systemd/system/hostapd.service. It's fixed root@routerOS:/var/log# systemctl start hostapd root@routerOS:/var/log# systemctl status hostapd ● hostapd.service - Access point and authentication server for Wi-Fi and Ethern........
  • i915 nouveau Nvidia GPU not starting lightdm Xorg failing solution for Could not determine valid watermarks for inherited state


    It may appear to be an Xorg or lightdm/gdm/mdm error but in reality for many users with this issue, it's a driver conflict and issue. I had a system that had two GPUs, an Intel and Nvidia GPU. The only thing that got it working was to remove the nouveau driver and blacklist it so it never came back, then the Intel GPU works fine without these issues. Solution sudo rmmod nouveau add nouveau/other driver to blacklist edit th........
  • amdgpu AMD GPU Xorg Won't Start [3576284.324] (EE) Segmentation fault at address 0x0 [3576284.325] (EE) Fatal server error: [3576284.325] (EE) Caught signal 11 (Segmentation fault). Server aborting


    Here is how Ifixed it on a Mint/Ubuntu install 1.) First download the latest AMDGPU-Pro driver from here: https://www.amd.com/en/support Navigate to your relevant video card: 2.) Download the installer One issue is that by default they give you a version for the latest version of........
  • LightDM Mint Ubuntu Debian won't start errors Nvidia Graphics


    This error implies that there may be an issue with Xorg or maybe your NVIDIA GPU cannot start or initialize: 35 laptop kernel: [ 2031.857704] nvidia: loading out-of-tree module taints kernel. 35 laptop kernel: [ 2031.857724] nvidia: module license 'NVIDIA' taints kernel. 35 laptop kernel: [ 2031.857725] Disabling lock debugging due to kernel taint 35 laptop kernel: [ 2031.873280] nvidia: module verification failed: signature a........
  • How To Do Linux Network Bonding Teaming in Mint Debian Ubuntu


    Bonding is an excellent way to get both increased redundancy and throughput. It is similar to the "Network Teaming" feature in Windows. There are a few different modes but we will use mode 6, I think it's the best of both worlds, as it is not just a failover, but it provides round robin, so you will get redundancy and load balancing. So if you have a 1G single port, you will have a combined throughput of 4G at this point. Just bear in mind that the true thr........
  • LXC Containers LXD How to Install and Configure Tutorial Ubuntu Debian Mint


    If you are using mint, delete the preference that stops snap from installing (as it is required for lxc) sudo rm /etc/apt/preferences.d/nosnap.pref 1. Install lxd: sudo apt install lxd Issues install lxd or errors? Click here Debian at this time does not have lxd so you'll need to use snap: sudo apt in........
  • Docker Tutorial HowTo Install Docker, Use and Create Docker Container Images Clustering Swarm Mode Monitoring Service Hosting Provider


    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.........
  • Zoom Password Error 'That passcode was incorrect' - Solution Wrong Passcode Wrong Meeting Name


    Have you been given a Zoom password that the meeting owner says is correct but it doesn't work anymore or never works? If the meeting name says "Zoom Meeting" and it's not really named that (which most meetings are not), then the issue is usually that there is an initial password to be able to join, aside from the passcode. It basically means that Zoom has deauthenticated you randomly or maybe after X amount of uses, without clicking on the Join Meeting URL which contains a........
  • How To Create OpenVPN Server for Secure Remote Corporate Access in Linux Debian/Mint/Ubuntu with client public key authentication


    Why choose OpenVPN instead of a firewall appliance? OpenVPN can be a reliable and easy replacement for traditional hardware or just be an additional tool that your company uses so that the firewall can focus on its job rather than acting as a VPNappliance at the same time. When comparing OpenVPN with traditional firewal........
  • HongKong VPS Server, Cloud, Dedicated Server, Co-Location, Datacenter The Best Guide on Hong Kong, China Internet IT/Computing


    In our 2024 VPS Server/Cloud Buyer's Guide, we place the location of your VPS/hosting/server as one of the priorities that is often overlooked. 2024 Update - Datacent........
  • pulseaudio issue on QEMU/KVM guest VM when microphone is replugged/unplugged pulseaudio: pa_threaded_mainloop_lock failed pulseaudio: Reason: Invalid argument


    Here is the scenario, you are using QEMU/KVM and are using something like the AC97 sound driver to pass the host audio to the guest via pulseaudio. This is useful because you can transparently pass your mic input from the host which means you can mute your microphone from the host, which prevents the guest from receiving any mic input even if unmuted. Mute / Unmute Fix This issue also seems to happen even if you press the mute button on the microphone and then unmute,........
  • Ubuntu/Debian Linux/Unix Howto Setup Install Syslinux Bootable USB with EFI and MBR from Command Line/CLI Terminal


    There aren't too many simple guides that show you how to use commands to setup your USB or other drive as a normal bootable drive where you can easily boot custom kernels or whatever OS you would like. 1. Get the tools we need: We install "syslinux" for MBR and "syslinux-efi" for EFI and "MBR" as we need a tool that embeds the actual MBR into our USB: sudo apt install syslinux syslinux-efi mbr........
  • Cisco Switch Howto Reset Password


    This was done on a 2900 but applies to all the switches of the same era. Step 1 - Power Cycle and enter recovery mode If you have physical access you can power cycle and hold the mode button down for 15 seconds. After that the SYS light will flash on the switch and you will see the following screenshot. If you don't have physical access (eg. it is a datacenter swich over console only) then power cycle and hit "Ctrl+Pause/B........
  • Cisco Router Password Reset Howto Guide Solution Cannot Login /Unknown Enable Password 2600, 2800, 2900, 3900


    It is common that you may get access to undocumented equipment and need to reset the password. This applies to many Cisco routers whether 2600, 2900, 3900 etc... Cisco's Guide says to hit Ctrl +Pause/Break but if it doesn't work on some devices causing people to say "cisco password reset pause break does not work", you can see Cisco's alternative key combinations here:........
  • EFI PXE grub2 Howto guide for Linux EFI PXE Booting on Debian, Mint, Ubuntu, RHEL


    Just a quick note and warning is that if you are testing to see if EFIPXE booting works on a VM, MAKE SURE it actually works. For example Iinitially tested using my Distro's QEMU 2.5+dfsg-5ubuntu10.46 and ovmf BIOS firmware (OVMF supports EFI). However, I found on old versions of QEMU (like 2.5), EFIbooting with GRUB NEVER works so it may appear that you have made a mistake when everything is fine when you boot a physi........
  • Juniper JunOS Command Overview and Howtos Switch, Router, Firewall Tutorial Guide


    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........
  • CentOS 7 8 PXEBoot Netinstall Not Working Solution "Pane is dead "new value non-exisetnt xfs filesystem is not valid as a default fs type"


    The problem seems to be that whatever kernel and initrd you have is tied to an old version of CentOS 7 that is no longer in the current repos of most mirrors. If you were previously able to PXEboot and install CentOS and you are sure your network and tftp are good the problem is that you have an outdated kernel and initramfs that point to a defunct version.........
  • CentOS 6 impossible to compile a newer libguestfs


    yum -y install gcc make gperf genisoimage flex bison ncurses ncurses-devel pcre-devel augeas-devel augeas readline-devel checking for cpio... cpio checking for gperf... no configure: error: gperf must be installed configure: error: Package requirements (augeas >= 1.2.0) were not met: Requested 'augeas >= 1.2.0' but version of augeas is 1.0.0 yum remove augeas augeas-libs augeas-devel wget http://downl........
  • How To Get Started on Ubuntu with gpt-2 OpenAI Text Prediction


    apt install software-properties-common add-apt-repository ppa:deadsnakes/ppa apt update apt install python3-pip apt install python3.7 curl gnupg python3.7-dev git ln -s /usr/bin/python3.7 /usr/bin/python3 pip3 install numpy keras_preprocessing curl https://bazel.build/bazel-release.pub.gpg | sudo apt-key add - echo "deb [arch=amd64] http://storage.googleapis.com/bazel-apt stable jdk1.8" | sudo tee /etc/apt/sources.list.d/bazel........
  • Remove cloud-init in your VM


    Unless you are using OpenStack, AWS etc then cloud-init is just some bloat that slows down the booting of your VMand can actually halt it from booting if it doesn't have a proper working IP (not good!). #remove cloud init! Debian based Ubuntu / Mint sudo apt remove cloud-init RHEL / CentOS based yum remove cloud-init ........
  • How To Install python 3.4 3.5 and up on Linux with wine - Working Solution


    This is sure simple if you follow the guide but it took a lot of hacking around to make this work on Debian/Ubuntu! Now before you ask why bother running wine and python, the reason is because Python executables are NOT cross-platform. If you run pyinstaller in Linux, that binary will only run on Linux and the same if you do it in Windows. So it is preferable if you have a single environment that you can create Linux and Windows binaries from rather than running 2 separate........
  • Howto Set Static IP on boot in initramfs for dropbear or other purposes NFS, Linux, Debian, Ubuntu, CentOS


    This is only really necessary in the case you don't want DHCP. If you are dealing with an encrypted LUKS server on the internet, you will often want to have a static IP so you know which IP to connect to (or if you have a semi-static IP assigned by DHCP). SET IP Address by /etc/initramfs-tools/initramfs.conf IP Address=192.168.1.27 Gateway=192.168.1.1 Subnet Mask: 255.255.255.0 Hostname=myhome.com IP=192.1........
  • Convert and install to LUKS Encrypted Drive Ubuntu 18.04 19.10 Linux Mint and Debian Based Linux


    The reason for doing this is that the installer doesn't seem to work properly for LUKS and the server installer doesn't even support LUKS anymore. When you use the GUI install on Desktop for LUKS it won't boot and will just hang after you enter your password. So the only reliable way is to do it ourselves. 1.) Make a default minimal install of Ubuntu 2.) Have a secondary disk on the server or VM. 3.)........
  • Debian and Netplan


    Create your netplan file vi /etc/netplan/01-netcfg.yaml network: version: 2 renderer: networkd ethernets: ens3: dhcp4: no ........
  • CentOS 8 how to convert to a bootable mdadm RAID software array


    The cool thing here is that we only need 1 drive to make a RAID 10 or RAID 1 array, we just tell the Linux mdadm utility that the other drive is "missing" and we can then add our original drive to the array after booting into our new RAID array. Step#1 Install tools we need yum -y install mdadm rsync Step #2 Create your partitions on the drive that will be our RAID array Here I assume it is /dev........
  • how to use ifplugd in Linux to execute a command or script when a NIC cable is unplugged or plugged in


    It is fairly simple to use once you know how to use it. However, the tricky thing is that by default it doesn't seem to be active or listen on any interface on manually specified. How To Install ifplugd First we install ifplugd sudo apt install ifplugd Let's enable it on our desired device(s) vi /etc/default/ifplugd set this line as so:........
  • mpv / mplayer with Radeon / AMD GPU Video Card Driver enable VDPAU GPU Accelerated Video Decoding


    The easiest way to know if your videos are playing with GPU acceleration are to watch the process of xplayer, mpv or whatever you are playing. The CPU usage should be no more than 10% for that process/program if it is using acceleration. Let's manually play with vdpau to make sure it works before we make it permanent: First make sure you have libvdpau installed: sudo apt install vdpau-driver-all If yo........
  • Ubuntu Debian Linux Mint r8169 r8168 Network Driver Problem and Solution


    This problem has been around forever, Linux seems to think it is fine to use the r8169 driver for an r8168 NIC but this often causes problems including the link not working at all. In my case ethttool shows the link up and detected but it simply does not work especially on a laptop that has been resumed from suspension. Sometimes it takes several minutes for it to work or to unplug and replug the ethernet. Here is the solution: Install th........
  • CentOS 6 and 7 / RHEL Persistent DHCP Solution


    It is very silly but the default on the ifup-eth script tells dhclient ( the program that obtains a DHCP IPaddress if you have selected DHCPin your ifcfg-eth* config file) to EXIT / QUIT if the first attempt to obtain a lease fails. No amount of dhclient.conf settings will fix this because if dhclient is started with -1 (which it is by default)then dhclient will quit. This is obviously very bad for MOST cases. Say for example you have a power outage or........
  • python import docx error


    sudo pip3 install python-docx [sudo] password for : Downloading/unpacking python-docx Downloading python-docx-0.8.10.tar.gz (5.5MB): 5.5MB downloaded Running setup.py (path:/tmp/pip_build_root/python-docx/setup.py) egg_info for package python-docx no previously-included directories found matching 'docs/.build' warning: no previously-included files matching '.DS_Store' foun........
  • qemu-kvm error "Could not initialize SDL(No available video device) - exiting"


    Now older versions of qemu-kvm didn't throw this error say if you just had "-video cirrus" when starting qemu-kvm. But newer versions do care. And this probably only applies to you if you are running from bash/terminal with remote kvm images. What you need to do is remove the "-video" part and just add -vnc :5 eg. this would fix the error: qemu-system-x86_64 -enable-kvm -boot order=cd,once=dc -m 1024 -drive........
  • Debian Ubuntu and Linux Mint Broken Kernel After Date - New Extra Module Naming Convention


    I don't consider a lot of these "extra" kernel modules "nice to have" as they often contain drivers for essential items like your soundcard, your NIC and many other devices that may not work. Sometimes you may find that "sound" or "ethernet" worked before a kernel/OS upgrade and now in the new version they don't. Often it will be because you need to install the "extra" kernel modules. One other weird thing is that sometimes........
  • Virtualbox vbox not starting


    If you've just installed VBox and it is not starting or working, the most common problem is usually that you don't have your kernel source installed, which means there is no kernel driver for vbox so it can't work. You may get an error that says "Kernel driver not installed" in your Virtualbox. So the first thing you should do is install your kernel source by running this: sudo apt-get install linux-headers-`uname -r`........
  • Ubuntu/Gnome/Mint/Centos How To Take a partial screenshot


    By default printscreen or alt print screen will get the whole desktop or the application in focus, respectively. But what if you want to select a portion of the screen? gnome-screenshot: ksnapshot compiz This is a nicely integrated solution sudo apt-get install compizconfig-s........
  • Cisco Unified Communications Manager / CUCM IP 8.6,10,12 Install Error Solution


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  • MySQL Recover/Reset Lost/Forgotten root Password


    One note is to secure MySQL, I don't know for sure but I believe you could login to MySQL remotely with no password during this operation (I'm not sure, maybe it doesn't accept blank passwords but I firewall MySQL port anyway and recommend you do the same). First edit /etc/my.cf Under the [mysqld] field add the following line somewhere: skip-grant-tables Now restart mysql: service mysql restart or on Debian sty........
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    From the package "parted" you can use the command "partprobe" to re-read the partition table. I really hate rebooting, and that's what Iloved to hear about AHCI motherboards, that they allow hotswap so you don't have to reboot. But that's only as good as the OS, if the OS does not reload the partition table you won't be able to do anything with that new drive you attached without rebooting. Yes, even without re-reading the partiton table Linux will........
  • Convert HDD/Hard Drive Partition(s) into non-RAID into RAID 1 using existing data without data loss and without reformatting.


    Before we start I take no responsibility for this, you should have a backup and if you make a mistake during this process you could wipe out all of your data. So backup somewhere else before starting this as a precaution, or make sure it's data you could afford to lose. The RAID 1 Setup (Hardware Wise) I've already setup my 2 x 1TB (Seagate) drives with identical partitions, make sure your new hard drive (the empty one) is setup like your curr........
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  • Linux Kernel Error (2.6.33.1) BUG: Bad page state in process swapper - Keeps rebooting - initramfs bug


    *This is a bug with initramfs support, all kernels after around 2.6.27.54 suffer from this problem. If you try to include initramfs into your kernel (I mean actually building your binaries into the kernel) this will always happen. Obviously some code has changed in recent kernels that is present in all new kernels, it makes it impossible to boot I've tried the latest 2.6.32, 2.6.33, 2.6.34, 2.6.35, 2.6.36, 2.6.37, 2.6.38 kernels and they all do this. I found one bug re........
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    100215 07:02:24 mysqld started /usr/libexec/mysqld: Can't read dir of '/tmp/' (Errcode: 13) /usr/libexec/mysqld: Can't create/write to file '/tmp/ibyP1qUC' (Errcode: 13) 100215 7:02:24 InnoDB: Error: unable to create temporary file; errno: 13 100215 7:02:24 [ERROR] Can't init databases 100215 7:02:24 [ERROR] Aborting 100215 7:02:24 [Note] /usr/libexec/mysqld: Shutdown complete 100215 07:02:........
  • yum error not working rpmdb: mmap: No such device TypeError: rpmdb open failed


    Loaded plugins: fastestmirror rpmdb: mmap: No such device error: db4 error(19) from dbenv->open: No such device error: cannot open Packages index using db3 - No such device (19) error: cannot open Packages database in /var/lib/rpm Traceback (most recent call last): File "/usr/bin/yum", line 29, in ? yummain.user_main(sys.argv[1:], exit_code=True) File "/usr/share/yum-cli/yummain.py&qu........
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    Have you ever seen this dreaded message in your Apache/HTTPD /var/log/httpd/error_log? [error] server reached MaxClients setting, consider raising the MaxClients setting The error itself is slightly misleading. Ibelieve this happened to one of my servers, I found Apache was running still, and that you could telnet to port 80 but no respnose would be given. For some reason my error log initially did not have the above error, but after a restart I saw........
  • How To Save iptables firewall rules Centos/Redhat/Fedora Linux


    This is something that annoys a lot of people, fortunately the Redhat style OS's are the most simple in this respect. I disagree that Debian's way makes sense, it is more of a hackish approach in how they implement iptables. Anyway, for those who are using Redhat/Centos style OS's it is very simple. Set your rules from the shell/command prompt and to save the iptables firewall rules so they are remember/loaded on boot just run this command: service iptables........
  • Using a Mac OSX DMG Image in Windows and Converting to Standard ISO Format use dmg2iso


    The dmg format is silly and annoying to work with, why couldn't Apple stick with the .iso standard? Anyway, there's an excellent Linux and Windows based tool to convert it back to a normal .iso Image called dmg2iso I'll only cover theLinux version although the Windows pre-built binary works the same way. Download dmg2iso here for free (from the author's website) It's just silly and doesn't make sense that Ubuntu doe........
  • RTL8111/8168B R8169 Gigabit Link slow speeds


    This is the Intel Atom 330 motherboard with integrated Realtek Gigabit NIC (Intel Desktop Board D945GCLF2 Motherboard W/ Atom 330 1.6 GHz Dual Core Processor - Mini-ITX) I cannot achieve more than 15 MB/s, even doing a local transfer through eth0 to it's own IP. 100% 95MB 15.9MB/s 00:06 So this is not a cabling, switch or hardware issue, it seems like a driver or chipset limitation problem. Here is my........
  • SSH Server Slow/Lagged/Delayed Login Response


    This is really something the SSHServer developers should consider. The cause of this annoyance is because of failed DNS lookups on your IPaddress, which is especially common for many dedicated/col-located servers and also computers on internal NAT/private networks. The chances are this is the cause of your SSHSlow/Delayed Login problems. The easy solution to SSH Login Problems Edit /etc/ssh/sshd_config Add this line to disable r........
  • SIOCSIFADDR No such device eth0 error while getting interface flags - eth0 Ethernet Device can


    Igot this after copying a VMWare image onto another machine in Debian. SIOCSIFADDR No such device eth0 error while getting interface flags The solution 1.) Find and edit the device line in persisent-net.rules note it will be prefixed with something like z25 or something else. vi /etc/udev/rules.d/z25_persistent-net.rules The easiest way is to comment anything out. If you are feeling........
  • Configuring OCFS2 Clustered File System on Debian Based Linux including Ubuntu and Kubuntu


    There's a lot of information and guides on OCFS2 for RHELand Centos Linux but the package setup and configuration is slightly different and this has thrown some people off. Installing OC2FS You should install the following packages to get started: apt-get install ocfs2-tools ocfs2console Configure OC2FS In RHEL/Centos the main configuration file is located in /etc/sysconfig/o2cb However in Debian based Linux it is located........
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