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Error: the following untracked working tree files would be overwritten by merge (Solved)

On my branch I had some files in .gitignore On a different branch those files are not. I want to merge the different branch into mine, and I don't care if those files are no longer ignored or not. Unfortunately I get this: 🥶The following untracked working tree files would

What is Shopify and how does it work: history, advantages and disadvantages of one of the great CMS for eCommerce

You may know very well what Shopify is and how it works, or at least it will sound familiar to you, but what you may not be so clear about is its history. And that's why we are here 😉 What is Shopify: the origin This CMS was founded a few

How to Integrate Software? Best Integration Solution Like Zapier

Introduction Zapier is an integration platform that allows you to connect your apps and automate tasks. The service can help you reduce the time spent on manual data entry, remove repetitive work and ensure that everything happens in the right order. As a result, it enables you to focus on

What is Email Search Engine? 6 Best Email Search Engine Tools

Email search engine is a tool that helps you identify who owns a specific email address. This information can be beneficial in many situations, from sales to eCommerce marketing and even security. In this article, we'll explain how email search engines work, as well as recommend some of the best

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 from that file. You can use awk to split the whole database dump into separate databases. * first save this script * and then run it against all_dbs.sql file:

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 databases with tables in MyISAM format which you'd like to convert to InnoDB, here is a bash script which will do it. The script only converts MyISAM tables, and will

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 3306), you may notice that whatever port you specify, it will connect you to the default MySQL server running on port 3306: This is because if you specify "-h localhost"

MySQL: changing ROW FORMAT to DYNAMIC or COMPRESSED

f you've changed your database properties to use innodb_large_prefix = 1 and innodb_file_format = Barracuda in my.cnf as below: you may want to convert all your existing tables to use DYNAMIC or COMPRESSED ROW_FORMAT. For a single table, you need to run the following: To convert

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 will end up with MySQL processlist full of "Waiting for table metadata lock" - including your original ALTER TABLE statement, MySQL processlimit will be reached, and your website/system will

PostgreSQL: create a user with password and assign it to a database

To create a database user in PostgreSQL, do: Then, to create a database and assign our user to it: To verify - try connect using a wrong password: This is connecting with a good password:

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 file uploads larger than allowed by nginx. To change it, add a larger client_max_body_size value to your nginx config. By default, the value is 1 megabyte. To

Running Debian on Thecus n5200

It's rather easy to install any Linux of your choice on Thecus n5200 or n5200 Pro: it's a normal, x86-based PC! By default, Thecus ships n5200 with a 64 MB flash disk, and 256 MB RAM. The easiest way to install a full-flavoured Linux is to: * open your Thecus n5200

Running Debian on Thecus n4100

Installation Installing is very similar to installing Debian on Thecus n2100 - see http://david.thg.se/n2100/. You will need a serial port, and a tftp server. Note that there is no Debian installer for Thecus n4100, so n2100 installation instructions from cyrius.com will not work. alternative installation

Running Debian on Freecom FSG-3

Freecom FSG-3 is a small device with these specs: * Intel IXP425/IXP422 (ARM) CPU, running at 266 MHz * 64 MB RAM * 1 - WAN port and 3 - LAN ports * 4 USB ports * 1 eSATA port * HDD, ranging from 80 GB to 500 GB (depending on model) If the original

Running Debian on ASUS WL-500W

This initial page is based on Running_Debian_on_ASUS_WL-500G_deluxe. Please bear in mind this page is under construction and depends also on other enthousiasts who contribute to make this page in final stage. It would be nice to see detailed instructions to get the wireless to work

Running Debian on ASUS WL-500G deluxe:Additional hardware

Go back to the main "Running Debian on ASUS..." page. USB cameras Philips pwc webcams WL-500gP works with Philips webcams using pwc module. I did transcode a live stream using vlc and it worked fine. Wireless So far, it is not possible to use Broadcom mini-PCI. I tried two alternatives,

Running Debian on ASUS WL-500G deluxe

You can run Debian (mipsel port) on ASUS WL-500g Deluxe, ASUS WL-500g Premium, ASUS WL-700gE, Linksys WRTSL54GS (and probably on similar, mipsel-based routers). See also a separate page for running Debian on ASUS WL-500W. ASUS WL-500g Deluxe is a small router with 200 MHz CPU, 32 MB RAM, 5 ethernet

“Error: queue file write error” with Postfix and Amavis

If you’re using Postfix and Amavis, you may be seeing “Error: queue file write error”, especially with larger than usually email rates. Here is what you can do to get rid of them. If you’re getting too many of such messages: In main.cf, try adding: The default

Viewing Linux console screens

If you want to see what's displayed on a certain Linux console screen remotely (i.e., you've left some programs running, or want to see the output of some program you started before etc.), log in to the machine you want and do: To see the first console (ctrl+atl+

Using openssl instead of telnet to test HTTPS, POP3S connections

SSL is being used more often than plain text connections, so the usual testing with telnet may not work anymore. Fortunately, it's possible to use openssl command to test webservers, POP3S/IMAPS/SMTPS mailserver, FTPS servers etc. which use SSL. Testing HTTPS Testing SSMTP / SMTPS Or, to test TLS on

Unprivileged lxc containers and open file limit problem

If you’re running unprivileged lxc containers, you will notice that some software fail to install or start. For example, you may have this kind of problem on Ubuntu, when trying to install mongo: The problem is the following line in /etc/init/mongod.conf: Because it’s an unprivileged

Stale NFS handle

Ever rebooted your NFS server, just to find out that your NFS clients can’t access it any more, with an error message “Stale NFS file handle”? If this happened to you and you have your NFS server’s exports on a LVM volume, this means that you didn’t

SSH exit codes

ssh from OpenSSH exits with the exit status of the remote command or with 255 if an error occurred. ssh2 on z/OS uses these exit codes:

Source port routing

Sometimes, you may want some services (i.e. web) to be routed through a different interface. Here is a quick setup with some common problems. Assumptions: * 10.4.0.1 – your additional gateway, through which you only want to route web traffic (TCP port 80), * 10.4.0.2 – server

Simple filesystem read/write tracing with /proc/sys/vm/block dump

Ever wondered what is hammering your disk so now and then, but couldn’t figure out with top / htop / iotop and similar? Annoying, but constant 100-200 kB/s writes? Or, simply blktrace was an overkill (or not supported by the kernel)? To debug, try this one (setting block_dump to

Simple file sharing with Samba 4

A simple smb.conf for a read-only share in Samba 4 can look like below: You can mount it on Linux with: See also simple file sharing with Samba 3.

Shell: finding the biggest file on the server

Finding the largest files (size) on the server:

Scripting qemu / kvm monitor

There are some tasks in qemu / kvm monitor which could be scripted (i.e. like changing VNC password on demand). Here is how to do it with netcat and minicom. Using netcat (nc) Use this option: Then you can do: You can also use nc -U to access the unix

Rsync exit codes

List of standard rsync exit codes This is a list of rsync exit codes (rsync status codes / rsync error codes / rsync exit values).   Exit code 127 If you're seeing exit code 127 after running rsync (i.e. in a script), it can mean you don't even have rsync binary installed

Routing with multiple network cards

Once I needed to setup routing on a Linux machine with multiple (two, three, or more) network cards, but all connected to the same switch, and all in the same subnet. Some aspects of such a setup might remind bonding, but it's not. Normally, in such setup, if you established

Resizing qcow2 images

To date (as of qemu 0.12.5), it was not possible to resize qcow2 images. The only workaround was to convert the image to some other format, resize it, and convert it back to qcow2. Which could be quite lengthy and meant plenty of IO. Moreover, it was even

Repairing broken PostgreSQL databases / tables

If your server happened to crash, PostgresSQL database is corrupted, but didn’t contain too precious information, you may try the following fix. The typical symptoms of a corrupted Postgres database would be like below: or The actual fix is quite easy, and basically sets “zero_damaged_pages = on”, then

Problems starting elasticsearch in Ubuntu 16.04

After you install elasticsearch in Ubuntu 16.04 (using apt install elasticsearch), you may notice it doesn't run. Nothing interesting in the logs, but definitely the process is not running. How to solve the problem? * in /etc/default/elasticsearch, make sure these are uncommented: * make sure /var/lib/elasticsearch is

PostgreSQL: create a user with password and assign it to a database

To create a database user in PostgreSQL, do: Then, to create a database and assign our user to it: To verify - try connect using a wrong password: This is connecting with a good password:

Poor write performance on Fusion MPT SAS RAID controllers

If you have a hardware RAID controller using mptsas module on your Linux server, you may notice your write performance is extremely poor – i.e. some database workloads can be 30x slower than on other servers (i.e. using Linux software RAID). An example card below – lspci shows: How can

Plesk: "The specified limit is invalid" when trying to change mailbox quota

Plesk web interface is poorly designed and lets you do operations which will break core functionality - for example, you may end up being unable to change mailbox quota. However, it is still possible to manipulate mailbox quota via MySQL - below, we will change the quota from 100 to

OpenSSH: tunnel-only user

To create a SSH user which is only allowed SSH tunneling, add the following to /etc/ssh/sshd_config:

OpenSSH: sftp-only chrooted user

To create a SSH user which is only allowed SFTP access (and is not allowed SSH/shell access), add the following to /etc/ssh/sshd_config: Please note that for this to work, user's home directory must be owned by root - otherwise, sshd will refuse the login. You may

NODE.JS: sh: 1: node: Permission denied

You might be getting this one when running commands as root: If you're really sure what you're doing, you may try to run these to "fix":

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 file uploads larger than allowed by nginx. To change it, add a larger client_max_body_size value to your nginx config. By default, the value is 1 megabyte. To

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 username/pass matches (i.e. you want all users to present a valid username/pass match, but want to let some automated checks coming from specified IPs through, i.e.

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 from that file. You can use awk to split the whole database dump into separate databases. * first save this script * and then run it against all_dbs.sql file:

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 databases with tables in MyISAM format which you'd like to convert to InnoDB, here is a bash script which will do it. The script only converts MyISAM tables, and will

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 3306), you may notice that whatever port you specify, it will connect you to the default MySQL server running on port 3306: This is because if you specify "-h localhost"

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 as below: you may want to convert all your existing tables to use DYNAMIC or COMPRESSED ROW_FORMAT. For a single table, you need to run the following: To convert

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 that it’s also replicated? In my.cnf on both servers, add a second database: Connect to mysql on both servers and add a new database: Now, restart mysql on

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 IPs in WHM GUI, but it’s possible to do so via SSH (login as root). First, you need to create a /var/cpanel/mainips/ directory, if it doesn’t

Mongo: enabling user auth

By default, mongo runs with user auth disabled. To enable it, do the following: Create admin user First, connect to admin database and create "admin" user (it can be named anything, does not necessarily need to be called "admin"): Enable user auth in mongod.conf and restart mongod In /etc/

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/cron.d/mdadm). To check if a test is running, do: As you can see, it is running, with 90K/sec speed (very overloaded array). To cancel a running test,

Java leap second bug – 30 June / 1 July 2012 – fix

Update: the same fix works for 30 June / 1 July 2015 issue. If your java applications suddenly started to use 100% CPU, you’ve hit java leap second bug (actually it’s a bug in Linux kernel, just java programs seem to be severely affected). First, you may check if

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 new functionality didn't expose your home network to public IPv6 traffic (since your devices, in most cases, will have a public IPv6 address assigned). Checking if your PC/laptop is

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 really surprised - since the LOG target is kernel logging, and LXD containers are pretty much limited when it comes to accessing various kernel functions, for security reason. A workaround

Hpacucli: Error: No controllers detected (with hpsa module in use)

If you’ve migrated to a newer kernel and a newer hpsa module is used instead of cciss, you may wonder why you’re no longer able to use hpacucli tool to see the status of your RAID device: If your RAID controller is similar to the one below (I’

GRE tunnel between two LXD hosts

You will need LXD > 2.3: On server1, with IP 1.2.3.4: On server2, with IP 5.6.7.8 on vmbr0:

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 was probably newly installed). To fix (on Ubuntu or Debian systems): And retry the git command:

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 messages: Here is what you can do to get rid of it. Add the following to /etc/sysctl.conf and run sysctl -p:

Generating DKIM key with openssl

Generating 1024 bit DKIM key To generate a DKIM key with openssl, do the following - this will generate you a 1024 bit DKIM key: Your generated public key will remind something like below: If you need to supply the public.key in the DNS record as follows, you have

Generate SSL dhparam file with openssl

To generate your dhparam file, run the following command in the terminal (note it may take a few minutes to complete): Include it in nginx config within server { ... } with:

Ffmpeg video conversion command line examples

Convert a video to a different resolution This one converts a video to 1366x600 resolution (-vf scale=1366:600) and leaves subtitles intact (-scodec copy -map 0): Record a selenium session running in Xvfb

Enabling OpenVPN with systemctl

If your distribution just switched to systemctl (i.e. Ubuntu 16.04) you may notice that your custom OpenVPN configs placed in /etc/openvpn/*.conf no longer start. Also, it gives no clues in the log on why it wouldn't start. This is because they are managed by systemctl now

Enabling IPv6 on CentOS

In case IPv6 is not enabled on your CentOS box, you may want to check /etc/modprobe.d/ipv6.conf file: To enable IPv6, comment out "options ipv6 disable=1" line and reboot.

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 properly, here is a short description on downgrading to PHP 5.3. * First, add these two lines to /etc/apt/sources.list. In short, it adds Debian Squeeze repositories as

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 on and off - here is how to disable it permanently. This may also work on some other Dell laptops (i.e. Precision 5510). It basically makes your 15 inch

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 on port 111 with netstat or ss: * disable rpcbind: * verify it's no longer 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) and Linux (or any other operating system running X). Here is how to do it: * First, list the devices your X sees: * Now, list details for the mouse (id=3)

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 match, run:

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 this, you may experience 404 when trying to install the packages with apt-get, or update sources lists. If you’re not going to upgrade to Debian Squeeze, here are /etc/

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 UTC) and we want to make it human readable: * Same as above, but we’d rather make the date output in a different format: * Need the above for a different

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: To find and remove both empty files and directories, you can use:

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 packages to tape, or copy them somewhere else. Note that you have to set up an "archive host", as described in BackupPC documentation. Change the variables and other details to

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 elastic IPs, from CLI (i.e. to make sure you don’t have any servers with proxy or SMTP open relay)? Here is a small bash script that will do

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 shows that one of the drives is failed. lspci was showing the following output for the storage controller in this IBM System x3550 server:02:00.0 RAID bus controller:

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 (http://). Here is how to achieve it with Apache webserver:

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 without git control, and would like to push it to bitbucket, you may get the following error: No refs in common and none specified; doing nothing. Perhaps you should specify

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 station? Probably several times, and usually, you had to log in using either VNC or RDP (Remote Desktop Protocol – Microsoft Terminal Services). If you’re used to SSH, you may

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 svnadmin create a SVN project structure there: * now, import your initial version of the website: * add users – first, in /srv/svn/yoursite.example.com/conf/passwd: * and in /srv/svn/

Sitemap.xml for Mailman

If you ever wondered how to generate a sitemap file for Mailman (the GNU Mailing List Manager), to be submitted i.e. to Google, here is how. All you have to do is replacing a few variables, and submitting the sitemap to your favourite search engine. It is based on

Repairing broken PostgreSQL databases / tables

If your server happened to crash, PostgresSQL database is corrupted, but didn’t contain too precious information, you may try the following fix. The typical symptoms of a corrupted Postgres database would be like below: or The actual fix is quite easy, and basically sets “zero_damaged_pages = on”, then

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 databases with tables in MyISAM format which you'd like to convert to InnoDB, here is a bash script which will do it. The script only converts MyISAM tables, and will

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 packages to tape, or copy them somewhere else. Note that you have to set up an "archive host", as described in BackupPC documentation. Change the variables and other details to

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 elastic IPs, from CLI (i.e. to make sure you don’t have any servers with proxy or SMTP open relay)? Here is a small bash script that will do

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 packages, here is how. Backup first Needless to say, please backup your Redmine installation before trying to upgrade it. Repositories There is a deb package available in Debian unstable. To

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 to create a "LAN" for containers on a single server - just attach them to the same bridge, use the same subnet (i.e. 10.10.10.0/24) -

Static compilation of cpuminer

If you want to compile cpuminer statically, you will notice it fails quite fast with the output similar to: This is because you don't have the right version of libraries and development packages installed in your system. To compile cpuminer statically, you will need to: * compile and install OpenSSL * compile

Sitemap.xml for Mailman

If you ever wondered how to generate a sitemap file for Mailman (the GNU Mailing List Manager), to be submitted i.e. to Google, here is how. All you have to do is replacing a few variables, and submitting the sitemap to your favourite search engine. It is based on

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 DKIM-signing in Exim, but then, some older mail systems may still use DomainKeys. Currently, Exim does not support signing mails with both DomainKeys and DKIM. You have to pick one

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 unsecure when used over internet: * rsync protocol transfers data in plain text - meaning, it can be easily listened to by a middleman * rsync credential exchange is encrypted using a

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 to use mbootpack utility: "It takes a multiboot kernel and modules (e.g. a Xen VMM, linux kernel and initrd), and packages them up as a single file that looks

Running Debian on Thecus n5200

It's rather easy to install any Linux of your choice on Thecus n5200 or n5200 Pro: it's a normal, x86-based PC! By default, Thecus ships n5200 with a 64 MB flash disk, and 256 MB RAM. The easiest way to install a full-flavoured Linux is to: * open your Thecus n5200

Running Debian on Thecus n4100

Installation Installing is very similar to installing Debian on Thecus n2100 - see http://david.thg.se/n2100/. You will need a serial port, and a tftp server. Note that there is no Debian installer for Thecus n4100, so n2100 installation instructions from cyrius.com will not work. alternative installation

Running Debian on Freecom FSG-3

Freecom FSG-3 is a small device with these specs: * Intel IXP425/IXP422 (ARM) CPU, running at 266 MHz * 64 MB RAM * 1 - WAN port and 3 - LAN ports * 4 USB ports * 1 eSATA port * HDD, ranging from 80 GB to 500 GB (depending on model) If the original

Running Debian on ASUS WL-500W

This initial page is based on Running_Debian_on_ASUS_WL-500G_deluxe. Please bear in mind this page is under construction and depends also on other enthousiasts who contribute to make this page in final stage. It would be nice to see detailed instructions to get the wireless to work

Running Debian on ASUS WL-500G deluxe:Downloads

Go back to the main "Running Debian on ASUS..." page. Downloads Newest kernels You can get the newest kernels here: https://lxadm.com/files/debian-asus/ Flash Images for ASUS WL-500g Deluxe 2.6.19.2 openwrt-brcm47xx-2.6-jffs2-64k.trx.bz2 (921600 bytes) - 2.6.19.2 kernel image for ASUS

Running Debian on ASUS WL-500G deluxe:Additional hardware

Go back to the main "Running Debian on ASUS..." page. USB cameras Philips pwc webcams WL-500gP works with Philips webcams using pwc module. I did transcode a live stream using vlc and it worked fine. Wireless So far, it is not possible to use Broadcom mini-PCI. I tried two alternatives,

Running Debian on ASUS WL-500G deluxe

You can run Debian (mipsel port) on ASUS WL-500g Deluxe, ASUS WL-500g Premium, ASUS WL-700gE, Linksys WRTSL54GS (and probably on similar, mipsel-based routers). See also a separate page for running Debian on ASUS WL-500W. ASUS WL-500g Deluxe is a small router with 200 MHz CPU, 32 MB RAM, 5 ethernet

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 small howto. Do it on your own responsibility, you may brick your device! This method should work on any Linux distribution, be it Ubuntu, Debian, Fedora and so on. My

Renaming mongo shards

Mongo has mostly excellent documentation, yet sometimes it may not be obvious how to do some less-used configuration changes. One of these is a way to rename mongo shards. Renaming mongo shards can be done in the following way: * assume you have “non-portable” naming like this – if your server addresses

REL="nofollow" and Mailman

Was your Mailman mailing list ever devastated by spambots? If yes, you may consider adding REL="nofollow" attributes to all postings sent to your mailing list. Usage: * copy the script somewhere to your server * edit $searchpath - point it to Mailman's "archives" directory * if you have any domains you wish

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 was tens of thousands: http://www.h-online.com/open/news/item/Large-botnet-attacks-WordPress-installations-worldwide-1841950.html In theory, if you use a strong password, you should be safe – but there is one more

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 requirements * separate IP for each SSL certificate * different domains you will use for your mail (say, example.com and example2.com) * separate SSL certificate for each domain The change will

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 will end up with MySQL processlist full of "Waiting for table metadata lock" - including your original ALTER TABLE statement, MySQL processlimit will be reached, and your website/system will

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 although Mailman can be integrated with Google search, this method is discouraged - it normally takes several weeks until Googlebot crawls your new posts. However, Mailman can be easily integrated

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 Debian installer does not include firmware for Broadcom network cards. If you’re trying to install Debian and see an image like this, you have to make sure you have

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 it via SCP first, and then execute it via SSH. But why make two connections, when one is enough? To execute a local script or a program on a remote

Diskless / remote boot with Open-iSCSI:Troubleshooting

Go back to the main "Diskless / remote boot with Open-iSCSI" page. Additional info / troubleshooting never connect more than one PC to the same iSCSI target name Traditional filesystems, like ext3, are designed to be run on one host at a time only. If you mount such a filesystem on more

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 (compressed with tar+bz2) size: 1791933 bytes md5sum: 4eabeb845d991333f60979dd61d5cd2c For your convenience, an image that will boot a diskless PC remotely (PXE / tftp + Open-iSCSI). It contains an integrated kernel 2.

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 care of these things: * create an initrd which will connect the iSCSI node * configure your tftp server, so that your machine starts properly via PXE/tftp This HOWTO explains how

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. List of requirements * separate IP for each SSL certificate * different domains you will use for your mail (say, example.com and example2.com) * separate SSL certificates for each domain The

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 configuration typically consist of one monitor, keyboard and mouse for each user.1. Surprisingly, no major Linux distro offers automated tools to configure a multiseat workstation. You should be familiar

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 router was to be sent to a remote location with no IT staff, ISDN line was the only way to talk to the device if everything else fails. Of course,

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 used with ProFTPD. By default, Debian Lenny does not provide mod_sftp support, but you can build a proper package using a development version available in Debian repositories – here is

Using fault injection

Some time ago, I was playing with logfs, a scalable flash filesystem. It’s interesting because of at least three reasons: * it can compress data transparently, * it provides wear leveling, * it works with block devices. In other words, a perfect filesystem to use for all flash-based devices, like USB-sticks. Any

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 a book, with built-in HDD, 4 ethernet ports, 4 USB ports, 64 MB RAM, and 266 MHz Intel XScale CPU (ARM). With these specs, it’s more powerful than some

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 ietd process is restarted (ietd restart, machine restart etc.). This is because on ietd shutdown, the user space daemon is just killed, but it doesn’t have the corresponding signal

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, a rock-solid operation of iSCSI is mandatory. The system should not fail even if the connection between iSCSI target and initiator is broken. IET, or iSCSI Enterprise Target, is an

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 RAID levels. Software RAID in Linux we use can be managed with mdadm tool. Devices used by RAID are /dev/mdX, X being the number of a RAID device, for

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 me as a surprise that it lets you read files which belong to other users, including those containing database credentials (like, the whole contents wp-config.php belonging to other user’

DRDB and link compression

Recently I was setting up DRBD (in short: “block devices designed as a building block to form high availability (HA) clusters”) between two data centers. DRBD doesn’t apply any form of compression on the data that is replicated; is it a good idea to enable compression in the VPN

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 at night, so why shouldn’t we scale CPU frequency down when servers are idle? Unfortunately, simple tests revealed serious performance problems when reading from a drive encrypted with dm-crypt

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 Internet top-level domains (TLD), it's not always the case. For example, CSR with country code "UK" will be invalid for United Kingdom (although confusingly, country TLD domain is .uk); you

Cipher benchmark for dm-crypt / LUKS

Do you have a netbook, laptop, desktop or a server which uses dm-crypt to encrypt data on your disks? If yes, you will probably find that raw hard disk performance is better than encrypted disk performance. You will notice that especially on slow machines (i.e. netbooks), but also high-performance

Acer accepting Windows tax refund

Getting a laptop without Windows is really problematic. How about getting a refund for a Windows system you’re not going to use? I've tried asking Acer, and it’s no easy task (it’s technically possible, but will cost you more than a refund you get, since you have

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