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You might be getting this one when running commands as root: If you're really sure what you're doing, you may
Nginx: 413 Request Entity Too Large
If you're seeing HTTP 413 "Request Entity Too Large" errors in your nginx logs, most likely this is caused by
Nginx HTTP basic auth – allowing IP or password-based access
nginx uses similar syntax to that of Apache to allow users to access a directory, depending if their IP or
MySQL: unattended Percona Server 5.7 installation
Percona Server 5.7 needs slightly different answers passed to debconf-set-selections to allow unattended / silent installation:
MySQL: split whole database dump into separate databases
If you have dumped all MySQL databases into one file (mysqldump --all-databases), you may have issues restoring a single database
MySQL: connecting to different ports on localhost
If you want to use mysql command to connect to MySQL server running on localhost, but on nonstandard port (not
MySQL: changing ROW FORMAT to DYNAMIC or COMPRESSED
If you've changed your database properties to use innodb_large_prefix = 1 and innodb_file_format = Barracuda in my.cnf
MySQL replication: adding a new database
Sometimes, you will see MySQL setups where only one database is being replicated. How to add a second database, so
Multiple shared IPs in WHM
Ever wondered how to set up multiple shared IPs in WHM? Here is how. You can’t add multiple shared
Mongo: enabling user auth
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Mdadm: stopping and starting RAID check in Linux
Linux distributions like Debian or Ubuntu with software RAID (mdadm) run a check once a month (as defined in /etc/
Java leap second bug – 30 June / 1 July 2012 – fix
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IPv6: blocking incoming traffic with ip6tables
If your internet provider started supporting IPv6 in addition to the usual IPv4, you may want to make sure the
Iptables: LOG target not working in LXD containers
If you're using LXD, you may be surprised that you're not getting packets logged with iptables' LOG target. Or, not
Hpacucli: Error: No controllers detected (with hpsa module in use)
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GRE tunnel between two LXD hosts
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Git clone: Problem with the SSL CA cert
're getting the following error when cloning a git repository: You may be missing ca-certificates package on your system (which
Getting rid of “IPv6 addrconf: prefix with wrong length 56”
Some hosting companies, notably OVH, have their networking set in a way that it constantly “pollutes” dmesg with the following
Generating DKIM key with OpenSSL
To generate a DKIM (DomainKeys Identified Mail) key with OpenSSL, you can use the following steps: 1. Open a terminal
Generate SSL dhparam file with openssl
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Ffmpeg video conversion command line examples
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Enabling OpenVPN with systemctl
If your distribution just switched to systemctl (i.e. Ubuntu 16.04) you may notice that your custom OpenVPN configs
Enabling IPv6 on CentOS
In case IPv6 is not enabled on your CentOS box, you may want to check /etc/modprobe.d/ipv6.conf
Downgrading to PHP 5.3 on Debian Wheezy (7.0)
Debian Wheezy comes with PHP 5.4. If this is too new for your application and it doesn’t work
Disabling fan on Dell Precision 5520
If any fan noise on your brand new Dell Precision 5520 with Ubuntu annoys you, or your fan constantly switches
Disable systemd listening on port 111
If your systemd listens on port 111 but you don't want that, please do the following steps: * verify it's listening
Disable / Enable Keyboard and Mouse in Linux
Sometimes, you may need to disable mouse and keyboard on a remote server / PC running X (i.e. over SSH)
Decoding SSL certificates and signing requests with OpenSSL
* To decode a certificate, run: * To decode a certificate signing request (CSR), run: * To check if the key and crt
Debian Lenny, /etc/apt/sources.list and error 404
Since Debian Lenny is now deprecated and no longer supported, its packages are now removed from the mirrors. Because of
Date conversion oneliners in bash
Some handy date conversion oneliners in bash. * Assuming we have a unix timestamp format (seconds since 1970-01-01 00:00:00
Bash: find and remove empty files and directories
To find and remove empty files (0-byte files), you can use: To find and remove empty directories, you can use:
AWS: IAM policy to allow EC2 volume snapshotting
The following AWS IAM policy allows EC2 volume snapshotting:
Arcconf on Linux: examples
Here are some arcconf usage examples. Adaptec Storage Manager (arcconf) can be downloaded from here. Note that the second example
Apache: serving different robots.txt for SSL and non-SSL version of the website
Sometimes, you may want SSL (https://) version of your websites to have different robots.txt than the plain text version
Adding existing code to bitbucket
Bitbucket has a bit imprecise documentation about pushing an existing code to their repo. If you have an existing directory
Accessing Windows console remotely from Linux
Have you ever needed to execute a command or to connect to an interactive text console on a remote Windows
A quick SVN repository set up for your website
A quick SVN setup example. * choose a location where your SVN server will keep data – for example, /srv/svn; use
MySQL: Converting all tables in all databases from MyISAM to InnoDB
With MySQL, for most use cases, InnoDB is a much better database engine than MyISAM. If you have plenty of
BackupPC - restoring backups from command line
This simple script makes tar.gz packages for hosts you have in your BackupPC archive. You can later write these
AWS: listing your EC2 instances IP addresses from command line
Increasing number of instances running on Amazon AWS / EC2, ever wondered how to get their list of IP addresses, including
Upgrading Redmine from 1.4.4 to 2.3.x on Debian Wheezy using deb packages
Debian Wheezy comes with Redmine 1.4.4. If you want to upgrade to Redmine 2.3.x using deb
Unicast VXLAN: overlay network for multiple servers with dozens of containers
Introduction Virtualization is a great technology, as it lets you run multiple virtual systems on a single server. It's easy
Static compilation of cpuminer
If you want to compile cpuminer statically, you will notice it fails quite fast with the output similar to: This
Sitemap.xml for Mailman
If you ever wondered how to generate a sitemap file for Mailman (the GNU Mailing List Manager), to be submitted
Setting up DKIMproxy with Exim for DKIM and DomainKeys signing
Was your mail ever rejected or tagged as spam because it didn’t have a DKIM signature? You could enable
Secure rsync over SSH without shell access
Summary Rsync is one of the best local and remote syncing programs. However, there is one problem with it: it's
Running Xen with LILO
Normally, Xen will not work with LILO, as LILO can't use multiple initrd images, which Xen needs. A workaround is
Rooting Motorola Droid Razr xt910 from Linux
If you want to root your Motorola Droid Razr xt910, but can’t find proper Linux docs, here is a
Renaming mongo shards
Mongo has mostly excellent documentation, yet sometimes it may not be obvious how to do some less-used configuration changes. One
REL="nofollow" and Mailman
Was your Mailman mailing list ever devastated by spambots? If yes, you may consider adding REL="nofollow" attributes to all
Protecting WordPress wp-admin / wp-login.php areas against dictionary attacks and DDoS
For some time, large botnet installations have been attacking WordPress installations from many IPs, sometimes the number of attacking addresses
Postfix and multiple SSL certificates
If you ever wanted to use your Postfix with multiple SSL certificates for different domains, here is how. List of
MySQL: avoiding "Waiting for table metadata lock" when executing "ALTER TABLE"
If you're running a busy database, the chances are that a ALTER TABLE statement executed will not really work, you
Integrating Mailman with a Swish-e search engine
Mailman is a very popular mailing list manager. Unfortunately, one feature Mailman doesn't provide is searching its archives. Note that
Installing Debian Squeeze on DELL PowerEdge R710 via DRAC
Installing Debian Squeeze on DELL PowerEdge R710 via DRAC can be quite an adventure – the main problem is that the
Executing local programs and scripts remotely
Theory If you want to execute a local command (be it a script or a program) remotely, you can upload
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Go back to the main "Diskless / remote boot with Open-iSCSI" page. Additional info / troubleshooting never connect more than one PC
Diskless / remote boot with Open-iSCSI:Downloads
Go back to the main "Diskless / remote boot with Open-iSCSI" page. Downloads initrd.tar.bz2 - an example initrd directory
Diskless / remote boot with Open-iSCSI
Background It is possible to start a diskless machine remotely using Open-iSCSI on the client side. You have to take
Cyrus IMAP server and multiple SSL certificates
If you ever wanted to use your Cyrus IMAP server with multiple SSL certificates for different domains, here is how.
Configuring multiseat X workstation
Introduction A multiseat, multi-station or multiterminal configuration is a single computer which supports multiple users at the same time. The
Configuring ISDN (dialin, dialout) from command line
I needed to configure ISDN on a small, Linux-based router, powered with a tiny 200 MHz mipsel CPU. As the
Building ProFTPD with SFTP support on Debian Lenny
The mod_sftp module in ProFTPD implements the SSH2, SFTP and SCP protocols, allowing SCP and SFTP clients to be
Using fault injection
Some time ago, I was playing with logfs, a scalable flash filesystem. It’s interesting because of at least three
The smallest Windows domain controller on Earth
For some time, I’ve been playing with Debian on Freecom FSG-3. The device is quite cool – a size of
Solving reliability and scalability problems with iSCSI, part 2
The latest stable IET release, 0.4.15, suffers yet another misfeature: it will likely break all initiators when the
Solving reliability and scalability problems with iSCSI
Because datacenters are very dependent on iSCSI, with an increasing amount of diskless servers booted directly off iSCSI NAS devices,
Software RAID in Linux - overview
This article focuses on managing software RAID level 1 (RAID1) in Linux, but similar approach could be used to other
Serious security flaw in WHM/cPanel – symlinks and .htaccess can be evil
WHM/cPanel is one of the most successful web hosting control panel. Especially popular among shared hostings, it came to
DRDB and link compression
Recently I was setting up DRBD (in short: “block devices designed as a building block to form high availability (HA)
CPUfreq and dm-crypt performance problems
Is using CPU frequency scaling on a server a good idea? After all, some servers don’t do very much
Country codes for SSL certificates
You have to specify a valid country code in Certificate Signing Request (CSR). Although usually country codes for CSRs match