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If you’re finding that when going to your web page it’s taking a little too long to make the connection, or its just running sluggsih – it may be trying to resolve your ip via a DNS lookup.

There are many performance tweaking options to tune your apache configuration, but I’m going to start by handling just this one.

Now by default HostnameLookups should be Off. And can be found in

/etc/apache2/apache2.conf
HostnameLookups Off

But you may also want to add it to the httpd.conf

/etc/apache2/httpd.conf

And restart apache

sudo /etc/init.d/apache2 restart

This may or may not fix your performance issues, but it sure did help me greatly! (Even though it was set to off in the apache2.conf file, adding it to the httpd.conf file increased my performance)

An interesting article you may find useful HERE

If you find your SSH client is taking too long to connect (and ask you for the password), or you’re trying to SFTP and it’s timing out before the password prompt. It’s probably trying to do a DNS lookup!

It’s a quick and easy fix! Just edit the following file:

/etc/ssh/sshd_config

And add or change the following:

UseDNS no

Restart SSH

sudo /etc/init.d/ssh restart

It seems obvious you’ve come across the following error while trying to setup SSL certificates on apache.

Error code: ssl_error_rx_record_too_long

Well more often than not, you have something mis-configured! (Likely the listening port: 443). What you might want to do is check that your firewall or iptables allows incoming connections on 443.

Ubuntu:

#sudo ufw allow 443

Ok, wonderful – that probably didn’t fix your problem. But now try going to the following address

http://www.domain.tld:443

If you’ve successfully seen something at the above page, it means your sites are listening on that port for non-ssl. I’ll assume that your apache virtual host file has something along the lines of:

NameVirtualHost *

<VirtualHost *>

What you’re going to want to do is force your vhosts to listen specifically on the proper ports. Changing to the following:

NameVirtualHost *:80

<VirtualHost *:80>

If you’re using ubuntu your ports.conf file should likely have 443 enabled on the listening port, and you may also have default-ssl listed in your /etc/apache2/sites-available/ folder. In which case you may want to enable that.

#sudo a2ensite /etc/apache2/sites-available/default-ssl

Basically that file has the following inside of it

<IfModule mod_ssl.c>
<VirtualHost _default_:443>
…… your server name / document root …..
SSLEngine on
SSLCertificateFile    /etc/ssl/certs/server.crt
SSLCertificateKeyFile /etc/ssl/private/server.key</VirtualHost>
</IfModule>

While you can use a single “shared” SSL certificate for multiple hosts, if each host needs it’s own SSL, they will need static ip addresses.

You may come across the circumstance where you have one ip subnet with a gateway ip on a different subnet.

Lets say for instance your static ip is 10.10.0.1 and you need to set the gateway as 9.9.0.1. After your initial setup of static ip, you may notice the destination is unreachable.

configure your static ip via command line

sudo nano /etc/netowork/interfaces

if you hapen to be using centos or fedora, you may use something similar to

system-config-network

(or)

setup

in ubuntu using the /etc/network/interfaces file

auto eth0
iface eth0 inet static
address 10.10.0.1
netmask 255.255.255.0
gateway 9.9.0.1

now while all looks right, you probably won’t be able to get online. You can restart your interface with

sudo /etc/init.d/network restart

if you add a custom route to the host and set the default gateway you should then be able to access something

sudo route add -host 9.9.0.1 eth0

sudo route add default gw 9.9.0.1

hopefully everything should be good to go! Make sure that your /etc/resolve.conf file has proper name servers for your isp.

nameserver 123.123.123.123

Now in order to make these changes persistant on startup/reboot you may add them to the /etc/network/interfaces file, but typically that has never worked for me across any distro.

What I do is add them to my rc.local file (which is executed after all other system modules are brought online).

sudo nano /etc/rc.d/rc.local

/sbin/route add -host 9.9.0.1 eth0
/sbin/route add default gw 9.9.0.1

This should help bring your network back online in case of power outage or reboot. Keep in mind that if you /etc/init.d/network restart you will likely have to manually add those routes by hand again. (no biggie).

To check your routing table just simply

route -n

Ok, I’m sure that at one point or another we’ve all come across:

Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 1966080 bytes)

Or some similar number of bytes, when trying to execute various web based php scripts or applications. The easiest way to change this is to drop in a .htaccess file with the following line (in your html directory)

php_value memory_limit 32M

If you have access to your php.ini file or wish to make the change that way, just change the following line to whatever Meg of ram you want. (Try 32M)

memory_limit 16M

Download the current tarbal for your architecture. (Mine is x86_64) Choose your’s accordingly.

wget http://downloads2.ioncube.com/loader_downloads/ioncube_loaders_lin_x86-64.tar.gz

next extract it

tar -zxvf ioncube_loaders_lin_x86-64.tar.gz

move the loader you need or just extract the whole dir to whatever location

sudo mv -R ioncube/ /usr/local/lib/

Edit your php ini file and add the following line:

sudo nano /etc/php5/apache2/php.ini

zend_extension=”/usr/local/lib/ioncube/ioncube_loader_lin_x.x.so”

restart apache

sudo /etc/init.d/apache restart

(or)

sudo apache2ctl restart

If you want to change the computer name of your linux box, it’s quite simple. Use the following commands to ensure the name is changed.

sudo nano /etc/hostname

And then make sure your hosts file is updated with the new name as well

sudo nano /etc/hosts

I typically use nano (pico) because to me it seems more user friendly and intutive. You may use vi or any such editor you wish.

In order to connect to a VPN you need a few things. Firstly you’ll need to install a VPN client. (Openvpn being my choice).

sudo apt-get install network-manager-openvpn

Then on the network icon on your task bar, right click and select “edit connections”.

Clicking on the VPN tab should now show the add/import buttons available. Click either depending on the files you were given by your system administrator (or whomever). Enter all your settings and select all the key locations and click OK when done.

Close the network connections box and then you are able to left click on the network icon on the taskbar, going to “VPN Connections” and selecing the VPN you just created. (A little lock will show up with a swirly thing going around your icon!).

Ubuntu Create an ISO image using the command line.

If you’re like me, you have a server or other system which doesn’t have an X system for various reasons. But you want to use all the hardware and create ISO’s or burn dvd’s from the command line for backups or what have you.

In order to copy a data disk or directory I use the following

dd if=/input/file of=outputfile.iso

Ripping dvd’s

mkisofs -dvd-video -o /home/dir/myiso.iso /media/dvdrom
growisofs -dvd-compat -Z /dev/dvd=myiso.iso

Removing the PC Speaker beep on Ubuntu, Debian or other Unix systems.

You can easily blacklist the pc speaker with the following commands.

rmmod pcspkr

open /etc/modprobe.d/blacklist and add the following line

blacklist pcspkr

to re-enable the pc speaker

modprobe pcspkr