When you are using MySQL, you will (likely) have tables that can be fragmented. In MySQL terms this is called "OPTIMIZE".
You could simply OPTIMIZE every table in every database, but during an OPTIMIZE, the tables are locked, so writing is not possible.
To minimize the time that MySQL will be locked (and results cannot be written), here is a script that checks fragmentation of every table of every database. Only if a table is fragmented, the table is OPTIMIZED.
echo -n "MySQL username: " ; read username
echo -n "MySQL password: " ; stty -echo ; read password ; stty echo ; echo
mysql -u $username -p"$password" -NBe "SHOW DATABASES;" | grep -v 'lost+found' | while read database ; do
mysql -u $username -p"$password" -NBe "SHOW TABLE STATUS;" $database | while read name engine version rowformat rows avgrowlength datalength maxdatalength indexlength datafree autoincrement createtime updatetime checktime collation checksum createoptions comment ; do
if [ "$datafree" -gt 0 ] ; then
fragmentation=$(($datafree * 100 / $datalength))
echo "$database.$name is $fragmentation% fragmented."
mysql -u "$username" -p"$password" -NBe "OPTIMIZE TABLE $name;" "$database"
Result will look something like this:
MySQL username: root
database.cache_filter is 19% fragmented.
meinit.cache_filter optimize status OK
database.cache_page is 35% fragmented.
meinit.cache_page optimize status OK
You may comment out that line with OPTIMIZE TABLE in it, if you are just interested in seeing the fragmentation.
I am not the first (and last) to write about carp, the failover/vip/floating-IP solution OpenBSD is using. Many articles describe this topic including a very complete answer to a frequently asked question about carp.
If you are not familiar with IP failover situations; in case of carp/pulse/HSRP/VIP, an IP "floats" between different machines. One machine actually answers request to received packets, so this is an solution that knows of a MASTER of ACTIVE node .
A CARP interface (which is not physical) is bound to a physical interface. The physical interface advertises statuses so other CARP interfaces know about each other.
You can bind almost any service to a CARP interface, some examples are:
Services that store data/stadia locally are not very suitable for a CARP solution. Examples are: DHCP (because leases are stored localy), MySQL/PostgreSQL (because data is stored on a physical local storage) and SSH (because you can never be sure what machine you are connecting to.
Here is how to set it up. On both boxes add a file /etc/hostname.carp0 with this content:
inet 192.168.1.123 255.255.0 192.168.1.255 vhid 1 pass SeCrEt carpdev em0
Remember to activate the interface like this: (All your network cards will be (re-) configured!)
# sh /etc/netstart
In this case, 192.168.1.123 is the floating IP address and em0 is the physical device that carp0 is running on. Be aware that the other server's carpdev should be connected to the same LAN.
Now that this is done, you may access services on the newly created CARP device's IP address. You may also specifically bind applications to only the CARP device.
You may check the status using ifconfig: (Please not the "carp: MASTER" part, it tells you this machine is the master, all others are "BACKUP".)
# ifconfig carp0
carp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
carp: MASTER carpdev em0 vhid 1 advbase 1 advskew 0
inet6 fe80::200:5eff:fe00:102%carp0 prefixlen 64 scopeid 0x5
inet 192.168.1.123 netmask 0xffffff00 broadcast 192.168.1.255
One limitation I found; you can not run dhclient on a carp interface, you will need to assign an IP address to the carp device. Please be aware that this would be a very odd setup; DHCP in a failover interface...
I have an existing network at home, but would like to be able to connect to it using a VPN every now and then. This enables me to access the fileserver, printer and so on.
A Soekris box I had lying around meets all requirements perfectly for a VPN-server. Here is how to set it up.
This one is easy enough, on Apple Mac OS X and a Time Capsule (or Airport Express) open AirPort Utility on your Mac, select the Time Capsule, click Manual Setup.
Go to Internet - NAT
Select the box "Enable NAT Port Mapping Protocol" and click on "Configure Port Mappings..."
Click on the "+" to add a portmapping. OpenVPN uses UDP port 1194, so map it from the "Public UDP Port(s)" to the "Private UDP Port(s)" on the "Private IP Address" of your soekris box. Fill in "OpenVPN" in the next "Description" field.
Finish your router configuration by pressing "Update". N.B. The network connection will be gone for a minute or two.
Create a directory /etc/openvpn/keys:
soekris # mkdir -p /etc/openvpn/keys
# This is the network that lives on the tun0 device.
# My regular network uses 10.0.1.0/24, so using
# 10.0.2.0/24 seems pretty logical.
server 10.0.2.0 255.255.255.0
# When clients connect, tell them that 10.0.1.0/24 can
# be reached through this tunnel. (You may also set this on the,
# client instead of "broadcasting" this...
push "route 10.0.1.0 255.255.255.0"
keepalive 10 120
This is quite an abstract step. It boils down to this: on the server you will create a certificate authority (ca) key and certificate, also you will create a key and certificate for each client connecting and sign them using your newly create certificate authority. The certificate from the certificate authority (ca.crt) and client (client1.crt) and the key for the client (client1.key) will be distributed to all clients. That's a mouth full, but here is how to do it in steps:
soekris # cp -Rip /usr/local/share/example/openvpn/easy-rsa /etc/openvpn
soekris # cd /etc/openvpn/easy-rsa/2.0
soekris # cat vars
echo NOTE: If you run ./clean-all, I will be doing a rm -rf on $KEY_DIR
export KEY_ORG="Me in It Consultancy"
export KEY_EMAIL="[email protected]"
Now execute these steps, as stolen from The OpenVPN homepage.
soekris # . vars
soekris # ./clean-all
soekris # ./build-ca
soekris # ./build-key-server server
soekris # ./build-key client1
soekris # ./build-key client2
soekris # ./build-key client3
soekris # ./build-dh
Once again; send the newly created file /etc/openvpn/keys/ca.crt, /etc/openvpn/keys/client1.crt and /etc/openvpn/keys/client1.key to the machine using the vpn connection.
This step enables client to reach your local network using network address translation. At the bare minimum, add this rule to your pf configuration in /etc/pf.conf
nat pass on sis0 from !(sis0) to any -> (sis0)
Also, make sure the packet filter is enabled and is using your pf.cofn
soekris # pfctl -e
soekris # pfclt -f /etc/pf.conf
And finally make sure it works after a reboot:
soekris # echo "ps=yes" >> /etc/rc.conf.local
Wow, almost there, let's start the software:
soekris # /usr/local/sbin/openvpn --config /etc/openvpn/server.conf --key /etc/openvpn/keys/server.key
Some debugging information will scroll down your screen.
Add these lines to your /etc/rc.local.
# Add your local startup actions here.
echo " openvpn"
/usr/local/sbin/openvpn --config /etc/openvpn/server.conf --key /etc/openvpn/keys/server.key >> /var/log/openvpn.output &
For now I am using the trail version of Viscosity because it looks great. Check out the screenshots below.
When you have setup an LVS you will need to administer it. Here are the tools you can use.
Log in to both boxes and issue the command:
Or, check /var/log/messages for a line like this:
pulse[$pid]: STARTING PULSE AS BACKUP
You could simple reboot the active machine. Otherwise, stop the service pulse for a moment on the active server. The backup will discover this and configure the floating IP.
On the active machine, issue:
# /etc/init.d/pulse stop
# sleep 60
# /etc/init.d/pulse start
Use the piranha web interface, located on port 3636 of either one of the load balancers. Remember to copy /etc/sysconfig/ha/lvs.cf to the backup machine as well.
After you have altered the configuration, restart pulse on the active machine. (Be aware; this makes services unavailable for a couple of seconds.
[services are printed]
# /etc/init.d/pulse restart
[services should be printed in a couple of seconds.]
There are quite a few howto's for LVS, but all of them are quite extensive. To be honest; you'll need to read them at some point, but for now let's try to make a very minimal howto for setting up LVS.
Configure the director/loadbalancer to have two NIC's. One side on a routable network, the other side connected to the machine running the services, called realservers.
# chkconfig ipvsadm on
# sed -i 's/net.ipv4.ip_forward = 0/net.ipv4.ip_forward = 1/' /etc/sysctl.conf
# sysctl -p
If you want your realservers to be able to use the internet, execute these lines on the director. Replace YOURREALSERVERLAN for the network address of the network where the real servers are located, for example. 192.168.1.0
# iptables -A POSTROURING -s YOURREALSERVERSLAN/24 -j MASQUERADE
# service iptables save
Fill in the blanks for PUBLICIP and REALSERVERIP. If you would like to add more servers to this virtual server, just repeast the last line a few times, changing the REALSERVERIP every time.
# echo "-A -t PUBLICIP:80" > /etc/sysconfig/ipvsadm
# echo "-a -t PUBLICIP:80 -r REALSERVERIP -m" >> /etc/sysconfig/ipvsadm
# service ipvsadm start
From a machine other then the redirector and/or the realserver, visit the ipaddress of your virtual ip.
N.B. I have spent quite some time trying to access the loadbalancer from the loadbalancer; this does not work.
Installing and using the monitoring tool Zabbix on OpenBSD is quite simple. Take just these steps to get started.
Use pkg_add to add these packages: (Versions could change over time.)
Make sure the apache daemons is started at boot time. (/etc/rc.conf.local)
Modify PHP to allow longer execution times and set the timezone:
$ grep max_execution_time /var/www/conf/php.ini
max_execution_time = 300
$ grep date.timezone /var/www/conf/php.ini
date.timezone = Europe/Amsterdam
$ sudo pkill httpd
$ sudo /usr/sbin/httpd
Get the latest release of Zabbix, untar it and use these options to configure it:
./configure --enable-server --with-pgsql --with-net-snmp --with-libcurl --enable-agent
Import database schemes as described in the Zabbix documentation, chapter 2.4.3: "Zabbix Server"
Create /etc/zabbix/zabbix_agentd.conf and /etc/zabbix/zabbix_server.conf by copying them from the untarred zabbix release:
# mkdir /etc/zabbix
# cp zabbix-1.6.5/misc/conf/zabbix_agentd.conf /etc/zabbix
# cp zabbix-1.6.5/misc/conf/zabbix_server.conf /etc/zabbix
Set DBName DBUser and DBPassword in /etc/zabbix/zabbix_server.conf.
$ cat /etc/rc.local
# $OpenBSD: rc.local,v 1.39 2006/07/28 20:19:46 sturm Exp $
# Site-specific startup actions, daemons, and other things which
# can be done AFTER your system goes into securemode. For actions
# which should be done BEFORE your system has gone into securemode
# please see /etc/rc.securelevel.
echo -n 'starting local daemons:'
# Add your local startup actions here.
if [ -x /usr/local/sbin/zabbix_agentd ] ; then
echo -n ' zabbix_agentd'
if [ -x /usr/local/sbin/zabbix_server ] ; then
echo -n ' zabbix_server'
You are practically done, now copy the php files and visit your zabbix installation:
# cp -Rip zabbix-1.6.5/frontends/php/* /var/www/htdocs/zabbix/
That's it, not extremely difficult!
If your are using the Terminal application of your Apple computer running Mac OS X, try bash programmable completion. It allow you to use the TAB key more often, for example in scp: (If you are using ssh-keys.)
$ scp shell01:/etc/pa
/etc/pam.d/ /etc/pam_smb.conf /etc/passwd
/etc/pam_pkcs11/ /etc/pango/ /etc/passwd-
$ scp shell01:/etc/pa
The steps to start using this great utility are these:
Apple iPhone OS 3.0 does not have crontab anymore. You are supposed to use launchd's facilities to execute something at a scheduled interval. Here is an example of a simple script to update the IP-address at DynDNS.org.
The script /var/mobile/update-dyndns.org contains:
wget -o /dev/null -O - http://ip.serverchief.com/ > /tmp/ip
if [ "$oldip" != "$ip" ] ; then
echo -n "$(date) "
echo $(/usr/local/bin/wget -O - "http://$user:[email protected]/nic/update?hostname=$host&wildcard=NOCHG&bacakmx=NOCHG" 2> /dev/null)
The file /var/LaunchDaemons/org.dyndns.update.plist contains:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
# launchctl load org.dyndns.update.plist
Now your IP will be update every 3-rd minute. Have fun!
Here is a step by step guide to help you get online with your iPhone using OS 3.0.
For tethering, an extra network interface is added, in my case "en5". To see what the IP-address of your connection is, open a Terminal and type:
In my case I see that I am using a private class (192.168.20.0/24) IP address. That means that T-Mobile in the Netherlands is NAT-ing my connection. Not a problem, but connecting back to my laptop is not possible from the internet.
Dates can be quite challenging. Especially if you systematically want to use dates, for example to compare what date is older.
If you would like to convert this date into epoch, take these steps.
$ # The first step is to print the date.
$ echo "2009/05/25 18:34:30;"
$ # This step is to strip the /-es.
$ echo "2009/05/25 18:34:30;" | sed 's%/%%g'
$ # This step removes the space
$ echo "2009/05/25 18:34:30;" | sed 's%/%%g;s% %%g'
$ # This step removes the trailing :30;.
$ echo "2009/05/25 18:34:30;" | sed 's%/%%g;s% %%g;s%:..;%%'
$ # This step removes the :.
$ echo "2009/05/25 18:34:30;" | sed 's%/%%g;s% %%g;s%:..;%%;s%:%%g'
$ # Finally feed that output to the "date" command.
$ date -j "+%s" $(echo "2009/05/25 18:34:30;" | sed 's%/%%g;s% %%g;s%:..;%%;s%:%%g')
On Mac OS X you'd have to use this command:
$ date -j -f date -j -f "%Y/%m/%d %T" "2009/10/15 04:58:06" +"%s"