Mount /tmp with noexec,nosuid options on Openvz

Simply do this :


# mount -t tmpfs -o noexec,nosuid tmpfs /tmp/
# cat /proc/mounts
simfs / simfs rw 0 0
proc /proc proc rw 0 0
sysfs /sys sysfs rw 0 0
devpts /dev/pts devpts rw 0 0
tmpfs /dev/shm tmpfs rw 0 0
tmpfs /tmp tmpfs rw,nosuid,noexec 0 0

and dont forget to insert to /etc/fstab :

tmpfs /tmp tmpfs noexec,nosuid 0 0
tmpfs /var/tmp tmpfs noexec,nosuid 0 0


Creating OpenVZ OSTemplate

Actually this article is not about creating OS template. Well, it’s about when you done customizing some OS Template and you want to backup or make it as a new pre-configured OS template :

1. Shutdown your OpenVZ container : vzctl stop {CTID}
2. As root, go to /vz/private/{CTID} and launch : tar -cvzf /vz/template/cache/{OSTemplate-Name}.tar.gz .

How to Enable CSF on OpenVZ Container

On the node server :
Modify IPTABLES_MODULES on /etc/sysconfig/iptables-config

IPTABLES_MODULES="ip_conntrack_netbios_ns ipt_conntrack ipt_LOG ipt_owner ipt_state ip_conntrack_ftp iptable_nat ip_nat_ftp ip_tables ipt_multiport iptable_filter ipt_limit"

then launch : service iptables restart
to restart iptables services

Then modify IPTABLES on /etc/vz/vz.conf

IPTABLES="ipt_REJECT ipt_tos ipt_limit ipt_multiport iptable_filter iptable_mangle ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_length ipt_state iptable_nat ip_nat_ftp ip_tables ipt_conntrack ip_conntrack_ftp ipt_LOG ipt_owner"
then launch : /etc/init.d/vz restart

How to Identify MySQL Slow Query

Long query on mysql often fill up your server’s CPU and RAM with a bunch of load. It can be happened because un-optimized query, dirty table, very large row, etc.

You can enable slow query log on your mysql server :

Edit your my.cnf config, under [mysqld] add :
log-slow-queries = /var/log/mysql-slow.log
long_query_time = 3
Create /var/log/mysql-slow.log and chmod it :
touch /var/log/mysql-slow.log
chown mysql.root /var/log/mysql-slow.log
Restart MySQL Services : service mysql restart

This will make MySQL to log queries that take more than 3 seconds to execute.

How to Use Screen on Linux

I’m not going to write what screen is about in this article. I just want to make a personal note for myself about this linux utility.

Starting screen :
#screen

Create a screen session :
Ctrl-a-c

Move to next screen session :
Ctrl-a-n

Move to previous screen session :
Ctrl-a-p

Detach current screen session :
Ctrl-a-d

To view current screen session :
#screen -ls
Output sample :
—————————————–
There is a screen on:
966.pts-0.helios (Detached)
1 Socket in /var/run/screen/S-root.
—————————————–

To reconnect to 966.pts-0.helios screen session :
#screen -r 966.pts-0.helios

That’s all. I hope my post can be useful to you

Change TimeZone on Centos Linux

It’s quite easy to change time zone on centos / linux os :
cp /usr/share/zoneinfo/Asia/Jakarta /etc/localtime

Change Asia/Jakarta into your location. After copying, you can run : ntpdate pool.ntp.org
to synchornize your server time with the closest public NTP server.

Analyzing Core Dump File

Yeah, I know core dump files may eat up user’s space quickly. But it is definitely a sign that something wrong with their scripts. So, keeping coredump files is sometimes useful so that we can analyze it properly. Here’s how to analyze core dump files :
strings /home/user/public_html/core.11051|head
You will find what scripts causing the coredump files.
or get a clear view with :
gdb /usr/bin/php /home/user/public_html/core.11051

Hope it can be useful for you!

Deal with /bin/rm: Argument list too long

As a linux user or administrator, you will someday will need to delete files that pile up your storage. If there are a lot of files (I dont know exactly how much), it will report :

/bin/rm: Argument list too long

Here’s how to handle it :

find . -name ‘[FILE-PREFIX]*’ | xargs rm

For example you want to delete cache_* files, the syntax is :

find . -name ‘cache_*’ | xargs rm

Selamat Hari Blogger

Seorang teman secara iseng menyatakan hal itu kepada saya dalam sebuah perjalanan panjang membosankan. Mungkin dari pada tidak ada suara, iseng, dan bingung mau ngobrol apa.

Saya jawab “Sorry man, saya bukan blogger”
Teman saya bilang “Tapi mas kan punya blog?”
Saya timpali “Ya, tapi saya nggak mau di bilang blogger”
“Kamu tahu kan, kita sering pusing gara – gara blogger yang enggak mau tahu tentang load, pasang plugin sampe puluhan biji, cerewet, dan suka protes”

“Bahkan barusan saja kita pusing gara2 database portal blog yang berGiga-giga?”

- silent – lalu ngakak!

Oke, saya tidak mengatakan saya benci blogger. Tapi saya jelas tidak mau disebut sebagai blogger. Emang kalau ngeblog trus disebut blogger?

Jadi apakah saya mendukung para blogger? Ya. Jadi – Selamat Hari Blogger yaa!?

Lapar Abadi

Lapar Abadi

Lapar Abadi adalah suatu sindrom dimana penderita merasakan kelaparan yang tak kunjung dapat terobati. Dalam kondisi ini, penderita akan memiliki kecenderungan untuk memakan apa saja, dimana saja, dan milik siapa saja.

Meski bukan pada jenis penyakit menular, lapar abadi memiliki beberapa efek samping yang dapat menimbulkan resiko kematian apabila tidak segera ditangani secara medis.

Resiko kematian ini sebenarnya tidak secara langsung ditimbulkan oleh lapar abadi. Biasanya kematian dijumpai pada penderita yang tidak selektif memilih makanan untuk mengobati gejala yang timbul.

Gejala Klinis

• Rasa lapar yang teramat sangat dalam jangka waktu yang cukup lama
• Kemarahan tidak terkendali sebagai efek samping rasa lapar tersebut
• Perasaan lemas akibat penderita mengalami kekurangan glukosa dalam tubuh

Sampai saat ini belum ada metoda pengobatan khusus untuk penderita lapar abadi. Biasanya kita hanya dapat mengendalikan situasi agar penderita tidak memakan makanan orang lain karena sanksi sosialnya cukup fatal.