Posts Tagged ‘conf’

My First Blog Entry

Sunday, November 5th, 2006

Today we first met Habib (a colleague from Holland College I study in). We took a newspaper and searched for him a living place. We called from one bulphone to some of the newspaper advertisements but was not able to find any suitable living place for the price he could afford (60 or 70 leva). After that we went to a coffee place called “Central”. Then we went to Mino’s coffee and stayed and talked for 3 or 4 hours with Habib mainly about Bangladej.He told us about different specific things in Bangladej, like for example he explained us the attitude of people to a local people who are musicians (I forgot the exact Bangla’s name of ‘em), he told us Bangla’s people will probably think of us we’re musicians if we go to Bangladej. He said the people appreciate this people as fortune and the musicians live on the hospitality of the people. I went home checked something on the servers. It seems there is a new RC release of clamav 0.90rc2. I installed the new release and tested it but it seemed it has some problems with the clamd.conf’s syntax and I’ve uninstalled the 0.90rc2 and installed the old one which is 0.88.5. Praise God I’m spiritually okay. I’m going to have a sleep now but I’ll first read a little (The Bible). Blessings in the name of Jesus Christ 🙂 !

How to disable nginx static requests access.log logging

Monday, March 5th, 2012

NGINX logo Static Content Serving Stop logging

One of the companies, where I'm employed runs nginx as a CDN (Content Delivery Network) server.
Actually nginx, today has become like a standard for delivering tremendous amounts of static content to clients.
The nginx, server load has recently increased with the number of requests, we have much more site visitors now.
Just recently I've noticed the log files are growing to enormous sizes and in reality this log files are not used at all.
As I've used disabling of web server logging as a way to improve Apache server performance in past time, I thought of implying the same little "trick" to improve the hardware utilization on the nginx server as well.

To disable logging, I proceeded and edit the /usr/local/nginx/conf/nginx.conf file, commenting inside every occurance of:

access_log /usr/local/nginx/logs/access.log main;

to

#access_log /usr/local/nginx/logs/access.log main;

Next, to load the new nginx.conf settings I did a restart:

nginx:~# killall -9 nginx; sleep 1; /etc/init.d/nginx start

I expected, this should be enough to disable completely access.log, browser request logins. Unfortunately /usr/local/nginx/logs/access.log was still displaying growing with:

nginx:~# tail -f /usr/local/nginx/logs/access.log

After a bit thorough reading of nginx.conf config rules, I've noticed there is a config directive:

access_log off;

Therefore to succesfully disable logging I had to edit config occurance of:

access_log /usr/local/nginx/logs/access.log main

to

After a bit thorough reading of nginx.conf config rules, I've noticed there is a config directive:

access_log off;

Therefore to succesfully disable logging I had to edit config occurance of:

access_log /usr/local/nginx/logs/access.log main

to

access_log /usr/local/nginx/logs/access.log main
access_log off;

Finally to load the new settings, which thanksfully this time worked, I did nginx restart:

nginx:~# killall -9 nginx; sleep 1; /etc/init.d/nginx start

And hooray! Thanks God, now nginx logging is disabled!

As a result, as expected the load avarage on the server reduced a bit 🙂

Fix of “Unable to allocate memory for pool.” PHP error messages

Saturday, October 15th, 2011

Since some time, I don’t know exactly where, after some updates of my WordPress running on a small server with FreeBSD 7.2. I’ve started getting a lot of Apache crashes. Often the wordpress scripts stopped working completely and I got only empty pages when trying to process the wordpress blog in a browser.

After a bunch of reading online, I’ve figured out that the cause might be PHP APC stands for Alternative PHP Cache .

I was not sure if the PHP running on the server had an APC configured at all so I used a phpinfo(); script to figure out if I had it loaded. I saw the APC among the loaded to show off in the list of loaded php modules, so this further led me to the idea the APC could be really causing the unexpected troubles.

Thus first I decided to disable the APC on a Virtualhost level for the domain where the crashing wordpress was hosted, to do I placed in the VirtualHost section in the Apache configuration /usr/local/etc/apache2/httpd.conf the following config directive:

php_flag apc.cache_by_default Off

These get me rid of the multiple errors:

PHP Warning: require_once() [function.require-once]: Unable to allocate memory for pool. in /usr/local/www/data-dist/blog/wp-content/plugins/tweet-old-post/top-admin.php on line 6

which constantly were re-occuring in php_error.log:

Further after evaluating all the websites hosted on the server and making sure none of which was really depending on APC , I’ve disabled the APC completely for PHP. To do so I issued:

echo 'apc.enabled = 0' >> /usr/local/etc/php.ini

Similarly on GNU/Linux to disable globally APC from PHP only the correct location to php.ini should be provided on Debian this is /etc/php5/apache2/php.ini .

Debian (Unstable) Squeeze / Sid /usr/lib32/alsa-lib/libasound_module_pcm_pulse.so linked to missing libraries

Thursday, September 10th, 2009

While playing with my installed programs on my recently updated Debian I stepped into a problem with /usr/lib32/alsa-lib/libasound_module_pcm_pulse.so. It seems the library was linked to two non-existing libraries: /emul/ia32-linux/lib/libwrap.so.0 as well as /emul/ia32-linux/usr/lib/libgdbm.so.3. A temporary solution to the issue is pointed out in Debian of the Debian Bug reports . As the report reads to solve that it’s required to:

1. Download libwrap0_7.6.q-18_i386.deb and libgdbm3_1.8.3-6+b1_i386.deb.

2. Extract the packages:dpkg -X libwrap0_7.6.q-18_i386.deb /emul/ia32-linux/dpkg -X libgdbm3_1.8.3-6+b1_i386.deb /emul/ia32-linux/

3. echo /emul/ia32-linux/lib >> /etc/ld.so.conf.d/ia32.conf

4. Execute /sbin/ldconfig

5. Check if all is properly linkedExecute ldd /usr/lib32/alsa-lib/libasound_module_pcm_pulse.so|grep -i “not found”Hopefully all should be fixed now.

How to fix Pulseaudio and Skype crappy sound glitches, choppy sound and crackling on Debian GNU / Linux

Tuesday, January 10th, 2012

I've experienced plenty of problems with Pulseaudio and Skype output sound hell crappy. This stupid proprietary program Skype is a total crap … Anyways again thanks to ArchLinux's wiki, I've used the two mentioned steps to fix all this Skype in / out problems …

1. Fix problems with Glitches, voice skips and crackling In file /etc/pulse/default.pa its necessery to substitute the line;

load-module module-udev-detect

with

load-module module-udev-detect tsched=0

2. Resolve Choppy sound in (Pulseaudio) -> Skype

In /etc/pulse/daemon.conf two lines has to be also substituted:

; default-sample-rate = 44100

Should become;

default-sample-rate = 48000

3. Change /etc/default/pulseaudio to allow dynamic module loading

It is a good idea to the default settings from DISALLOW_MODULE_LOADING=1 to DISALLOW_MODULE_LOADING=0 .This step is not required and I'm not sure if it has some influence on solving sound in / out problems with Skype but I believe it can be helpful in some cases..

So in /etc/default/pulseaudio Substitute:

DISALLOW_MODULE_LOADING=1

to;

DISALLOW_MODULE_LOADING=0

4. Restart PulseAudio server

After the line is changed and substituted a restart of PulseAudio is required. For PulseAudio server restart a gnome session logout is necessery. Just LogOff logged Gnome user and issue cmd:

debian:~# pkill pulseaudio

This will kill any left pulseaudio server previous instances.
 

How to turn off telnetd on FreeBSD

Sunday, December 25th, 2011

There is a brand new remote FreeBSD vulnerability in telnetd in all its versions starting from version 7 to 9. It is therefore advisable that the telnet daemon be completely disabled.

To disable telnetd on FreeBSD:

1. Open /etc/inetd.conf

freebsd# vi /etc/inetd.conf

2. Comment out the line

telnet stream tcp nowait root /usr/libexec/telnetd telnetd

e.g.:

#telnet stream tcp nowait root /usr/libexec/telnetd telnetd

3. Restart inetd

freebsd# /etc/rc.d/inetd restart

The whole remote root telnetd FreeBSD security advisory (SA), can be read here

List and get rid of obsolete program core dump files and completely disable core files on FreeBSD

Tuesday, November 1st, 2011

My FreeBSD router has started running out of space, I looked for ways to clean up some space. So I remembered some programs are generating core files while they crash. Some of these files are really huge and ban be from 1Mb to > 1G.

I used find to first list all my produced core files starting from root directory (/) , like so:

find / -name core -exec du -hsc {} ;
....

Having a list of my core files with the respective core file size and after reviewing, I deleted one by one the cores which were there just taking up space.
It’s a wise idea that core dumps file generation on program crash is completely disabled, however I forgot to disable cores, so I had plenty of the cores – (crash files which are handy for debug purposes and fixing the bug that caused the crash).

Further on I used an /etc/rc.confdumpdev=NO , variable which instructs the kernel to not generate core files on program crash:

freebsd# echo 'dumpdev=NO' >> /etc/rc.conf

Next, to make dumpdev=NO , take affect I rebooted the server:

freebsd# shutdown -r now
...

There is a way to instruct every server running daemon to know about the newly set dumpdev=NO by restarting each of the services with their init scripts individually, but I was too lazy to do that.

How to add Apache 301 redirect to VirtualHost in Apache

Sunday, September 25th, 2011

I’ve had two domain names which were pointing to the same website content.
As one can read in any SEO guide around this is a really bad practice as search engines things automatically there is a duplicate site content and this has automatically a negative effect on the site pagerank.
To deal with situation where multiple domains are pointing to the same websites its suggested by many SEO specialists that a 301 redirect is created from all the domain websites to a single website domain which will open the actual website.

Making the 301 direct domain from the sample domain my-redirect-domain.com to www.mydomain.com can be done with a virtualhost dfefinition in either httpd.conf or with the respective file containing the domain virtualhost definitions:
Here is the exact VirtualHost code I use to make a 301 redirect.

<VirtualHost *>  ServerAdmin support@mydomain.com  ServerName my-redirected-domain.com
ServerAlias my-redirected-domain.com www.my-redirected-domain.com
RewriteEngine on RewriteRule ^/(.*) http://www.mydomain.com/$1 [L,R=301]
</VirtualHost>

After placing the VirtualHost redirect, an apache redirect is required.
Further on when a Gooogle or Yahoo Bot visits the website and does any request to my-redirect-domain.com or www.my-redirect-domain.com , they will be redirected with a 301 reuturned code to www.mydomain.com

This kind of redirect however can have a negative impact on the Apache CPU use (performance), especially if the my-redirect-domain.com is high traffic domain. This is because the redirect is done with mod_rewrite.

Therefore it might be better on high traffic domains to create the mod_rewrite redirect by using a vhost like:

<VirtualHost *>
ServerAdmin support@mydomain.com
ServerName my-redirected-domain.com
Redirect 301 / http://www.mydomain.com/
</VirtualHost>

The downside of using the Apache 301 redirect capabilities like in the above example is that any passed domain urls like let’s say http://www.my-redirected-domain.com/support/ would not be 301 redirected to http://www.mydomain.com/support/ but instead the redirect will be done straight to http://www.mydomain.com/

Possible way to increase Linux TCP/IP port thoroughput via sysctl kernel variable

Thursday, August 25th, 2011

Sysctl is a great way to optimize Linux. sysctl has a dozens of values which could drastically improve server networking and overall performance.

One of the many heplful variables to optimize the way the Linuz kernel works on busy servers is net.ipv4.ip_local_port_range .

The default sysctl setting for net.ipv4.ip_local_port_range on Debian, Ubuntu Fedora, RHEL, CentOS is:

net.ipv4.ip_local_port_range = 32768 65536

This means that the kernel and the corresponding server running services instructing the Linuz kernel open new port sockets can only open local ports in the range of 32768 – 65536 .
On a regular Desktop GNU/Linux machine or a not high iron server this settins is perfectly fine, however on a high scale servers the local port range in the interval of 32768-65536 might be insufficient at times, especially if there are programs which require binding of many local ports.

Therefore on a high load servers, generally it’s a good to raise the port range to be assigned by kernel to 8912 – 65536 , to do so the setting has to be changed like shown below:

linux:~# sysctl -w net.ipv4.ip_local_port_range = 8192 65536
...

If changing this setting on the server doesn’t show any negative impact on performance in few hours time or a day or even better decreases the server average load, it’s a good idea that it be added to sysctl.conf to load up the setting on next kernel boot.

linux:~# echo 'net.ipv4.ip_local_port_range' >> /etc/sysctl.conf

Enjoy 😉

How to block IP address with pf on FreeBSD, NetBSD and OpenBSD

Wednesday, July 27th, 2011

Pf Firewall BSD logo

I’ve noticed some IPs which had a kind of too agressive behaviour towards my Apache webserver and thus decided to filter them out with the Firewall.
As the server is running FreeBSD and my firewall choise is bsd’s pf I added the following lines to my /etc/pf.conf to filter up the abiser IP:

table persist file "/etc/pf.blocked.ip.conf"
EXT_NIC="ml0" # interface connected to internet
block drop in log (all) quick on $EXT_NIC from to any
echo '123.123.123.123' >> /etc/pf.blocked.ip.conf

As you see I’m adding the malicious IP to /etc/pf.blocked.ip.conf, if I later decide to filter some other IPs I can add them up there and they will be loaded and filtered by pf on next pf restart.

Next I restarted my pf firewall definitions to make the newly added rules in pf.conf to load up.

freebsd# pfctl -d
freebsd# pfctl -e -f /etc/pf.conf

To show all IPs which will be inside the blockips filtering tables, later on I used:

pfctl -t blockips -T show

I can also later use pf to add later on new IPs to be blocked without bothering to restart the firewall with cmd:

freebsd# pfctl -t blockedips -T add 111.222.333.444

Deleting an IP is analogous and can be achieved with:

freebsd# pfctl -t blockedips -T delete 111.222.333.444

There are also logs stored about pf IP blocking as well as the other configured firewall rules in /var/log/pflog file.
Hope this is helpful to somebody.