This guide assumes you have a working Postfix server and want it to sign with DKIM. There are a few things we have to understand to make all of this work though, which require you to be familiar with DNS as well. 1.) Install OpenDKIM apt install opendkim systemctl enable opendkim 2.) Edit /etc/opendkim.conf Syslog yes SyslogSuccess yes Mode&nbs........

find /usr/share/zoneinfo/|sed s#"/usr/share/zoneinfo/"##g|grep "/"|grep -v posix|grep -v ^"Etc/"|grep -v ^right|grep -v ^"SystemV" Africa/Addis_Ababa Africa/Abidjan Africa/Blantyre Africa/Lusaka Africa/Casablanca Africa/Libreville Africa/Asmara Africa/Bujumbura Africa/Dakar Africa/Lagos Africa/Malabo Africa/Harare Africa/Kigali........

Is your /var/log/journal overweight and bloated? For example a decent install of Debian 11 with most applications and services ends up being about 4.9G with the journal taking a few gigs. du -hs /var/log/journal/ 1.3G /var/log/journal/ By default in a lot of distributions there is no maximum size so it will keep growing. This is especially problematic for embedded distributions and devices, but is also a huge waste of sp........

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.........

There are many reasons why Proxmox services may not start, but one common one, is if you have changed your /etc/hostname or /etc/hosts and don't have a valid FQDN (eg. proxmox01 instead proxmox01.com). Failed to start The Proxmox VE cluster filesystem. Failed to start Proxmox VE firewall. Failed to start PVE Status Daemon. Failed to start Proxmox VE scheduler. Failed to start PVE Cluster HA Resource Manager Daemon. Failed to star........

The reason we use the command below is because we need the md5sum value hash of the password. This means that we cannot use the md5sum Change "yournewpass" to the pass you want to set echo -n "yournewpass" | md5sum Then you get the md5sum hash of whatever you entered eg. in this case "yournewpass" 5a9351ed00c7d484486c571e7a78c913 ........

mysql reset root password. Oops I can't remember my MySQL root password! [root@centos7test etc]# mysql -u root -p Enter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES) First we need to stop mariadb: systemctl stop mariadb Now we need to restart it with skip-grant-tables whic........

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`........

If you get error messages like this it is usually because /var/run/sshd does not exist. root@userbox:/# service sshd status ● ssh.service - OpenBSD Secure Shell server Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enab Active: failed (Result: start-limit-hit) since Wed 2019-04-10 02:24:44 EDT; 1 Process: 511 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=255)........

The strange thing is that usually the first install or two will work on any new machine but then it suddenly won't. I had this experience on QEMU 2.13 on a different machine. There is something finicky or buggy about the CUCM installer even when choosing the same virtual hardware specs. qemu-kvm command: /usr/libexec/qemu-kvm -version QEMU PC emulator version 0.12.1 (qemu-kvm-0.12.1.2-2.506.el6_10.1), Copyright (c) 2003-2008 Fabrice Bellard ........

Before getting into the output here is my typical experience with SMART, there is what I call a "bad disk" with pending and uncorrectable sectors that cannot be reallocated. It has caused a kernel panic and system crash repeatedly as we can see from the logs. But SMART says it has "PASSED" its self assessment. SMART is still useful to me but it is more about looking at Current_Pending_Sector. Any time I have had anything but 0 for that attribute it........

systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system. The key commands or arguments you will use with systemctl are the following: Unit Commands: list-units [PATTERN...] List loaded units &nbs........

[root@thetor2017 conf]# service httpd restart Stopping httpd: [ OK ] Starting httpd: WARNING: MaxClients of 3000 exceeds ServerLimit value of 300 servers, lowering MaxClients to 300. To increase........

dvd+rw-mediainfo /dev/sr0 INQUIRY: [ASUS ][BW-16D1HT ][3.00] GET [CURRENT] CONFIGURATION: Mounted Media: 11h, DVD-R Sequential Media ID: RITEKF1&n........

Here is the only solution Ifound that works in Firefox: *Note you could basically just copy all of the commands in bold (the rest just shows the output) Install sqlite3 sqlite3 places.sqlite sqlite> .clone places.sqlite-fixed moz_places... done moz_historyvisits... done moz_inputhistory..........

In xplayer Iget the following error "Could not initialize supporting library.". It actually looks more like a gstreamer issue. For those wondering what the default video player is called it is "xvid" and not "totem" anymore like previous versions. Basically it looks like some codecs are missing when I uninstalled another program it uninstalled other programs and codecs that it shouldn't have. I've tried installing all the gstre........

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/........

To get the first X letters of a word: It's very simple you can just pipe it to head with -c 1 (gives the first letter and so on) -c2 (2 gives the first 2 letters). echo "dsjfsdlksjdklf;jlsd;kflasdj;kl"|head -c 2 Returns ds To get the last X letters of a word: Now we use tail with -c but it works differently. ........

Essentially a program I was running for mining did not terminate properly with Ctrl+C it is listed as defunct and cannot be killed, kernel is tainted and normal tricks to disable the port are impossible the dev and sys entries for the device cannot be browsed or interacted with in any form without a lockup of the request. The only solution is to reboot due to the kernel taint as far as I can find so far. [1130246.811056] INFO: task minerd:21861 blocked for more th........

user@box:~$ sudo tune2fs -l /dev/md99 [sudo] password for user: tune2fs 1.42.9 (4-Feb-2014) Filesystem volume name: Last mounted on: /mnt/md50 Filesystem UUID: 976a8655-2619-4587-878c-dab07f7b7652 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Fi........

This is a 8TB Seagate external USB 3.0 device apparently newer kernels use a module called "UAS" instead of "USB Storage" which causes issues as a lot of devices are not properly supported in UAS mode by the kernel driver. The solution some say is to disable UAS specifically for your USB device but I'd rather just disable UAS altogether. Solution blacklist UAS: *do not do this it does not work and just causes your USB 3.0........

These errors believe it or not are simply because of not being the root user or running with sudo! However if you didn't know to try as root you'd think there was a problem with your burner or disc Essentially it looks like without root you cannot send the required scsi commands to continue writing. Ithink cdrecord should have built-in tests or safeguards to see if it has the permissions to run the required commands. I guess for more advanced users the idea is simila........

Based on this tutorial: http://www.linuxjournal.com/content/overlay-images-video-using-mplayer-and-mencoder mencoder -oac pcm -ovc raw -vf bmovl=0:0:tfifo -o $output $file vf_bmovl: Unknown command: ''. Ignoring. ........

This happened while an mdadm array was syncing, all access from writing a new blank file to opening a small .txt file was very slow: [222117.312078] kjournald starting. Commit interval 5 seconds [222117.685060] EXT3-fs (md0): using internal journal [222117.685096] EXT3-fs (md0): mounted filesystem with ordered data mode [222122.376847] kjournald starting. Commit interval 5 seconds [222122.602825] EXT3-fs (md2): using internal jour........

This is a common mistake but many people do not realize this function comes from mysql itself, so therefore you need an active mysql connection open. Usually the string will be empty and null when you call it from outside of the database connection portion of your code. eg. an example of the wrong way and creating a null/empty string $var = mysql_real_escape_string($myself) mysql_connect(); // returns n........

The Scenario You have dual NICs and you disable NIC1 which uses 192.168.1.1 as its gateway. With NIC2 you enable it/connect it to another network which also has the gateway 192.168.1.1 Everything will work fine at this point. When switching back to NIC1 even with NIC2 disabled and even unplugged, the OS basically can't pick up the new/updated ARP entry of the old device for 192.168.1.1 and perhaps thinks it is a security risk or spoof of some sorts and blocks i........

You need to set your application type as "Desktop" even though this would sound counterintuitive.........

yum -y install dvdauthor ffmpeg mjpegtools sox bc rpm -ivh dvd-slideshow-0.8.4-2.noarch.rpm Preparing... ########################################### [100%] 1:dvd-slideshow ########################################### [100%] /usr/bin/dir2slideshow: line 553: bc: command not f........

Many may ask why would you need to do this? When upgrading from phpBB 2 to 3 the conversion does not keep the admin user you create. If your old admin user has an email address associated that no longer works or is accessible this makes it impossible to reset the admin password. Some may just say "I'll just manually edit the e-mail address" but it won't work and phpBB will fail to find that user if you don't update the "user_email_hash" field but how do........

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........

The best way I could figure out is to use another guest of some sort to do this, while assigning the disk that needs to be resized to the same guest. So say we have /dev/xvda as the guests drive and we've booted it up. We also have /dev/xvdb (this is going to be the image/disk to be resized). In this case it's based on an ext3/4 image. Run e2fsck on it to ensure there are no filesystem errors. e2fsck /dev/xvdb........

This is one in a series of weird things whichIthought was motherboard related (I RMA'd the motherboard), the RAM tests fine with memtest86 and I used badblocks on both RAID 1 members with no errors and smartctl is happy with them. Basically the array crashes the kernel a lot and has issues when writing. [112322.723465] md0: rw=0, want=14958668696, limit=1887460480 [112322.731077] attempt to access beyond end of device [112322.731087] md........

It really is as simple as: cdrecord -v dev=/dev/sr0 pathtoyourisoimage.iso -v is for verbose, I prefer it but if you don't you won't see as much output like below (I like to know the details and exactly what's happening) dev=/dev/sr0 specifies the device name of your burner (they say not to use it and to specify some weird annoying device string but using the raw /dev has always worked for me and is how it should have been implemented from the start IMHO)........

These were caused by a bad stick of Corsair RAM [] free_hot_cold_page+0xfc/0x150 [] __pagevec_free+0x14/0x1a [] release_pages+0x127/0x12f [] __pagevec_release+0x15/0x1d [] __invalid_mapping_pages+0x120/0x156 [........

I like dd, although it only reads it, usually a read test of the entire disk will uncover if your hard drive is bad in some parts. This is a good thing to do at least once a month, a lot of times bizarre program behavior, laginess and crashing/unnmounting problems etc.. are due to a failing disc and SMART won't know it or indicate a problem: We must also remember there's never a guarantee, I've found that ever since we moved to larger and more platters per drive with 1TB drives........

high IO wait 424 root 39 19 1900 848 552 D 0.0 0.0 0:00.91 updatedb root 424 0.0 0.0 1900 848 ? DN Mar11 0:00 /usr/bin/updatedb -f sysfs?rootfs?bdev?proc?cpuset?binfmt_misc?debugfs?sockfs?usbfs?pipefs?anon_inodefs?futexfs?tmpfs?inotifyfs?eventp........

Jan 16 04:02:03 centosbox syslogd 1.4.1: restart. Jan 16 04:07:34 centosbox kernel: INFO: task updatedb:20771 blocked for more than 300 seconds. Jan 16 04:07:34 centosbox kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Jan 16 04:07:34 centosbox kernel: updatedb D F78BE050 6476 20771 20766&n........

CPU/Kernel/MB/RAID problem? Jan 5 12:45:05 testbox kernel: [653298.890004] BUG: soft lockup - CPU#0 stuck for 61s! [hal-acl-tool:4168] Jan 5 12:45:05 testbox kernel: [653298.890005] Modules linked in: vmnet vmci vmmon binfmt_misc drbd video output input_polldev ocfs2_stackglue ocfs2_dlmfs ocfs2_dlm ocfs2_nodemanager configfs k8temp hwmon_vid lp snd_hda_intel snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi........

I separated the 2 drives in the RAID 1 array. 1 is the old one /dev/sda and is out of date, while the separated other one /dev/sdc was in another drive and mounted and used with more data (updated). I wonder how mdadm will handle this: usb-storage: device scan complete md: md127 stopped. md: bind md: md127: raid array is not clean -- starting background reconstruction raid1: raid set md127 active with 1 out of 2 m........

nautilus-gksu - privilege granting extension for nautilus using gksu nautilus-sendto - integrates Evolution and Pidgin into the Nautilus file manager nautilus-share - Nautilus extension to share folder using Samba nautilus-actions - nautilus extension to configure programs to launch nautilus-bzr - Bazaar (bzr) integration for nautilus nautilus-cd-burner - CD Burning front-end for Nautilus nautilus-clamscan - Antivirus scanning for Nautilus n........

I finally decided to look into some utils that did this, and the first one I found is "mp3burn". It is unbelievable simple and perfect. *2017-11 update and mp3burn is still available in standard repos such as Ubuntu 14/16 so this is a current and working project. Just install the package and it gets all required libraries to convert and then burn's on the fly. And you won't believe how simple it is. I just want to a directory that had the MP3's I wanted t........

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........

I successfully created a single RAID 1 partition which includes /boot inside it and my root directory through the Debian installer. It said GRUB installed successfully but when I try booting the OS it seems GRUB can't read anything. When trying to boot from GRUB GRUB Loading stage 1.5. GRUB loading, please wait... Error 2 I get "Error 2" when trying to boot Debian. I also notice from a LiveCD that........

I installed 5.5 with a 300GB RAID 1 partition (boot is also on this partition). It booted up fine the first few times until after I used a Live CD and accessed the array, and it became named /dev/md127 for some reason. Now whenI boot into CentOS I get a kernel panic and different errors, once I got "invalid superblock", even though the array is fine (it didn't happen again, probably because I was sure to dismount and stop the mdadm array properly). Here's what........

I have no idea why but mkfs.ext3 defaults to a patheticlly small blocksize of 1024 bytes/1KB (kilobyte). That means the maximum filesize is ONLY 16GB! With 2KB/2048 bytes you get a 256 GB maximum filesize, and with 4KB/4096 bytes you get 2TB! I finally noticed/paid attention to this after realizing that with rsync and scp that no file larger than 17GB could be transferred. I then realized it must be a file size limit on the partition. Here is what tune2fs tol........

Roxio/Sonic complaints - No verification of burnt ISO ImageThe only thing Nero does better is that it has the option to verify the data written from an ISO/CD Image! Why can't all burning utilities have this feature?........

DVD Burners and Media at an all time lowThis is crazy you can buy a nice Pioneer DVD burner for like $64 CAD now and good media like 50PC Maxell is just $25.97 at Walmart. I'm liking this. Time to make double archives of important data :)........

E-Mail TipI just thought I'd give you guys a good tip about e-mail. It seems a lot of people like to use a Hotmail or ISP (eg. Telus) account for their e-mail but the problem is what happens if you switch ISPs, then your e-mail address no longer works and old friends might not be able to contact you. The same thing has happened for excite.com e-mail addresses where they just shut down. Whether you are a business owner or personal user can you afford to lose an e-mail........

FreeBSD detected my burners as normal CD-ROMsDoes anyone know how to fix this?Having the same issue here .....I'll let you know once I solve it :)........

There's a lot of outdated information and confusion for system administrator's out there. One annoying task for many an Administrator has been backing up data in Linux. You don't need any GUI tools such as K3B or GnomeBaker. Both are excellent tools but for veteran command line users working remotely, using the keyboard is a great and possibly automated way to save yourself pain and hassle. At a later date we'll cover how scripting can automatically backup certain........