Linux | Joan Marc Riera Duocastella

Port Knocking!

Would you like to hide a port until a certain knock-knock procedure is received?

Like this:

knock3000 4000 5000 && ssh -puser@host && knock5000 4000 3000

Knock on ports to open a port to a service (ssh for example) and knock again to close the port.

Running applications automatically when X starts

The majority of people who use Debian upon the desktop launch straight into the X11 Window system, usually via one of the choosers xdm, gdm, or kdm. Once you’ve entered your username and password you get your Window Manager running and are ready to start work. But what if you want a program or two to start as soon as you login?

Continue reading “Running applications automatically when X starts”

Clean RAM and swap

Clean the linux ram and swap it’s easy.

# sync; echo 3 > /proc/sys/vm/drop_caches

Why this?
Continue reading “Clean RAM and swap”

Fast debian / ubuntu bonding

On debian : HOWTO

There is just one different thing on Ubuntu , aliases becomes modprobe.d/bonding.conf. (it should work anyway I guess. )

root@fbmgrid01:/home/sgeadmin# cat /etc/modprobe.d/bonding.conf

alias bond0 bonding options bonding mode=0 miimon=100

root@fbmgrid01:/home/sgeadmin# cat /etc/network/interfaces|grep -v ^#

auto lo
iface lo inet loopback

auto bond0
iface bond0 inet static
pre-up ifconfig bond0 up
pre-up ifconfig eth1 up
pre-up ifconfig eth0 up
address 84.88.79.131
netmask 255.255.255.192
gateway 84.88.79.129
dns-nameservers 84.88.79.2 84.88.79.3
dns-search barcelonamedia.org
up ifenslave bond0 eth1 eth0
down ifconfig eth1 down
down ifconfig eth0 down
down ifenslave -d bond0 eth1 eth0

And then just restart the network.

Enjoy.

Extend lvm mount point in 3 minutes

Follow the steps:

1) Add your new disk (Virtual disk or physical LUN)

2) Find them:

echo “- – -” > /sys/class/scsi_host/host0/scan

3) Do a partition (type 8e=> LVM)

fdisk /dev/sdb
n
p
default =1
default
t
8e
w

4) Create Physical Volume on partition

pvcreate /dev/sdb1

5) Add the PV to the Volume Group

vgdisplay # show your volume groups, I need to add sdb1 to fbmsvn01
vgextend fbmsvn01 /dev/sdb1

6) Add the new space on the VG to the Logical Volume(I add 5GB)

lvdisplay # shows your logical volumes , I need to extend /dev/fbmsvn01/var
lvextend -L+5G /dev/fbmsvn01/var

7) Resize the filesystem on the LV

resize2fs /dev/fbmsvn01/var # resize your partition, so it gets the new inodes. if it’s your root partition a backup may give you some peace.

8) done.

Extra documentation: http://www.cyberciti.biz/tips/vmware-add-a-new-hard-disk-without-rebooting-guest.html

Varnish is complaining

I’ve just upgraded a development server and I’ve found myself with this issue:

Starting Varnish

Internal error: cc(1) complained:

/usr/bin/ld: crti.o: No such file: No such file or directory

collect2: ld returned 1 exit status

Continue reading “Varnish is complaining”

python -m SimpleHTTPServer

Serve current directory tree at http://hostname:8000.

If more than one is needed it is able to receive another port at the end.

python -m SimpleHTTPServer 8000

Put your CPU to 100%

$ yes > /dev/null

With this command one of our cpus will go nuts. Use it for testing purpose only.

How to install Catalyst on debian lenny

I’ve readed this and made some minor modifications.

$sudo su

#echo “# repo for catalyst” >> /etc/apt/sources.list

#echo “deb http://ftp.us.debian.org/debian/ unstable main” >> /etc/apt/sources.list

#apt-get clean && apt-get update

#apt-get install sqlite3 libdbd-sqlite3-perl libcatalyst-perl
libcatalyst-modules-perl libdbix-class-timestamp-perl
libdatetime-format-sqlite-perl libconfig-general-perl libhtml-formfu-model-dbic-perl libterm-readline-perl-perl
libdbix-class-encodedcolumn-perl libperl6-junction-perl
libtest-pod-perl gcc make libc6-dev