Monthly Archives: May 2015

docker centos 7.1 systemd

cat Dockerfile FROM docker.io/centos MAINTAINER vitasis ENV container docker RUN yum clean all; yum -y install hostname tar git; yum -y update; yum clean all # https://bugzilla.redhat.com/show_bug.cgi?id=1118740 RUN yum -y swap -- remove systemd-libs -- install systemd systemd-libs; yum clean all; \ #RUN yum -y install systemd systemd-libs; yum clean all; \ (cd /lib/systemd/system/sysinit.target.wants/ && for i in *; do [ $i == systemd-tmpfiles-setup.service ] || rm -f $i; done); \ rm -f /lib/systemd/system/multi-user.target.wants/*;\ rm -f /etc/systemd/system/*.wants/*;\ rm -f /lib/systemd/system/local-fs.target.wants/*; \ rm -f /lib/systemd/system/sockets.target.wants/*udev*; \ rm -f /lib/systemd/system/sockets.target.wants/*initctl*; \ rm -f /lib/systemd/system/basic.target.wants/*;\ rm -f /lib/systemd/system/anaconda.target.wants/*; VOLUME [ "/sys/fs/cgroup" ] CMD ["/usr/sbin/init"]


sudo docker build --rm=true -t vitasis/centos7-systemd .

sudo docker run --name test --privileged -ti -v /sys/fs/cgroup:/sys/fs/cgroup:ro vitasis/centos7-systemd

sudo docker ps | grep test

sudo docker exec -i -t 63f43c4ccbba bash
Detected virtualization 'other'.
Welcome to CentOS Linux 7 (Core)!
Set hostname to <79251a373052>.

Cannot add dependency job for unit display-manager.service, ignoring: Unit display-manager.service failed to load: No such file or directory.

[  OK  ] Reached target Paths.

[  OK  ] Listening on Journal Socket.

[  OK  ] Listening on Delayed Shutdown Socket.

[  OK  ] Reached target Swap.

[  OK  ] Created slice Root Slice.

[  OK  ] Created slice System Slice.

[  OK  ] Reached target Slices.

[  OK  ] Reached target Local File Systems.

         Starting Create Volatile Files and Directories...

         Starting Journal Service...

[  OK  ] Started Journal Service.

[  OK  ] Started Create Volatile Files and Directories.

[  OK  ] Reached target System Initialization.

[  OK  ] Listening on D-Bus System Message Bus Socket.

[  OK  ] Reached target Sockets.

[  OK  ] Reached target Timers.

[  OK  ] Reached target Basic System.

[  OK  ] Reached target Multi-User System.

[  OK  ] Reached target Graphical Interface.
If you want to deatech form docker session, you need to use a daemon:
sudo docker run --name test --cap-add SYS_ADMIN -d -ti -v /sys/fs/cgroup:/sys/fs/cgroup:ro vitasis/centos7-systemd

privileged or SYS_ADMIN is needed, because of using mount with selinux or apparmor.

selinux policy modules

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semodule -l

custom java enviroments

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export PATH=$PATH:/opt/jdk1.8.0_45/bin:/opt/jdk1.8.0_45/jre/bin

linux alternatives

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If you want to have sevral versions of java and choose one of them:

cd /opt/jdk1.8.0_45/
alternatives –install /usr/bin/java java /opt/jdk1.8.0_45/bin/java 2
alternatives –config java

There are 3 programs which provide ‘java’.

Selection Command
———————————————–
* 1 /opt/jdk1.7.0_71/bin/java
+ 2 /opt/jdk1.8.0_25/bin/java
3 /opt/jdk1.8.0_45/bin/java

wget java

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wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u45-b14/jdk-8u45-linux-x64.tar.gz"

fedora join active direcroty

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yum install realmd
realm discover –verbose example.com
That will tell you what software you need to install (samba-common doesn’t show up, but it will if you try to join a domain and it’s not installed).
yum install sssd oddjob oddjob-mkhomedir adcli samba-common
realm join –client-software=sssd example.com -U mydomainadmin
That should prompt for a password, and if successful, absolutely nothing will be displayed on STDOUT.
To test if you have successfully joined the domain, use
getent passwd EXAMPLE\\mydomainuser
and you should get a long passwd line.

Now, if you want to only allow certain users to log in, you can run the next two commands:
realm deny –all
realm permit [email protected]

linux check if process is running send mail

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Check if some process is running and send mail when finish.

nohup sh -c ' while true; do s="" ; s=`pgrep rsync` ; [ -z "$s" ] && echo "rsync process done" | mail -s "rsync done" [email protected] && break ; done ' &

apache syn flood

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iptables -A INPUT -p tcp ! –syn -m state –state NEW -j DROP
iptables -A INPUT -f -j DROP
iptables -A INPUT -p tcp –tcp-flags ALL ALL -j DROP
iptables -A INPUT -p tcp –tcp-flags ALL NONE -j DROP

also nginx can help as proxy.

linux add (allow) more ports

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Check:
sysctl net.ipv4.ip_local_port_range

Add:
echo “net.ipv4.ip_local_port_range = 1024 65535” >> /etc/sysctl.conf

Applay:
sysctl -p

allow a range of ports in iptables

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iptables -A INPUT -p tcp –match multiport –dports 1024:3000 -j ACCEPT

checking for libmemcached location… configure: error: Unable to find memcached.h under

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Directadmin install memcached using percl problems.

cd /usr/local/src
wget https://launchpad.net/libmemcached/1.0/1.0.15/+download/libmemcached-1.0.15.tar.gz
tar -zxvf libmemcached-1.0.15.tar.gz
cd libmemcached-1.0.15
./configure
make
make install

nf_conntrack: table full, dropping packets

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sysctl -a|grep -i nf_conntrack_max

To interesas conntrack:

sysctl -w net.netfilter.nf_conntrack_max=131072
echo 32768 > /sys/module/nf_conntrack/parameters/hashsize
hashsize = nf_conntrack_max / 4

to save rules on server reboot:
echo ‘net.netfilter.nf_conntrack_count = 131072’ >> /etc/sysctl.conf
vi /etc/rc.local
echo 32768 > /sys/module/nf_conntrack/parameters/hashsize

To disable conntrack:

/sbin/rmmod iptable_nat
/sbin/rmmod ipt_MASQUERADE
/sbin/rmmod rmmod nf_nat
/sbin/rmmod rmmod nf_conntrack_ipv4
/sbin/rmmod nf_conntrack
/sbin/rmmod nf_defrag_ipv4

decking create docker cluster simple

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Decking json example:
vi decking.json
{ "containers": { "centos7a": "milcom/centos7-systemd", "centos7b": "milcom/centos7-systemd" }, "clusters": { "main": ["centos7a", "centos7b"] } }

And lets build:

sudo decking create main

centos7a ... centos7b ... centos7a creating... centos7b ... centos7a creating... ✔ centos7b ... centos7a creating... ✔ centos7b creating... centos7a creating... ✔ centos7b creating... ✔

sudo decking start main

centos7a ... centos7b ... centos7a starting... centos7b ... centos7a starting... ✔ centos7b ... centos7a starting... ✔ centos7b starting... centos7a starting... ✔ centos7b starting... ✔

sudo decking status main

centos7a ... centos7b ... centos7a ... centos7b running 172.17.0.2 centos7a running 172.17.0.1 centos7b running 172.17.0.2

Lets check if its really running:

c4175064768b milcom/centos7-systemd:latest “/usr/sbin/init” 3 minutes ago Up About a minute centos7b
b4b1766eb4d8 milcom/centos7-systemd:latest “/usr/sbin/init” 3 minutes ago Up About a minute centos7a

I guess its better than FIG.
Next step use ansible to manage these VM, its quit fast.

bash menu box

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Bash dialog box constructing:

#!/bin/bash # utilitymenu.sh - A sample shell script to display menus on screen # Store menu options selected by the user INPUT=/tmp/menu.sh.$$


# Storage file for displaying cal and date command output

OUTPUT=/tmp/output.sh.$$
# get text editor or fall back to vi_editor

vi_editor=${EDITOR-vi}
# trap and delete temp files

trap "rm $OUTPUT; rm $INPUT; exit" SIGHUP SIGINT SIGTERM
#

# Purpose - display output using msgbox

#  $1 -> set msgbox height

#  $2 -> set msgbox width

#  $3 -> set msgbox title

#

function display_output(){

	local h=${1-10}			# box height default 10

	local w=${2-41} 		# box width default 41

	local t=${3-Output} 	# box title

	dialog --backtitle "Linux Shell Script Tutorial" --title "${t}" --clear --msgbox "$(<$OUTPUT)" ${h} ${w}
}
#
# Purpose - display current system date & time
#
function show_date(){
	echo "Today is $(date) @ $(hostname -f)." >$OUTPUT

    display_output 6 60 "Date and Time"

}

#

# Purpose - display a calendar

#

function show_calendar(){

	cal >$OUTPUT

	display_output 13 25 "Calendar"

}

#

# set infinite loop

#

while true

do
### display main menu ###

dialog --clear  --help-button --backtitle "Linux Shell Script Tutorial" \

--title "[ M A I N - M E N U ]" \

--menu "You can use the UP/DOWN arrow keys, the first \n\

letter of the choice as a hot key, or the \n\

number keys 1-9 to choose an option.\n\

Choose the TASK" 15 50 4 \

Date/time "Displays date and time" \

Calendar "Displays a calendar" \

Editor "Start a text editor" \

Exit "Exit to the shell" 2>"${INPUT}"

menuitem=$(<"${INPUT}") # make decsion case $menuitem in Date/time) show_date;; Calendar) show_calendar;; Editor) $vi_editor;; Exit) echo "Bye"; break;; esac done # if temp files found, delete em [ -f $OUTPUT ] && rm $OUTPUT [ -f $INPUT ] && rm $INPUT

build qemu from source

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wget http://wiki.qemu-project.org/download/qemu-2.3.0.tar.bz2
./configure –disable-kvm [–prefix=PFX] [–target-list=”i386-softmmu x86_64-softmmu”]
make
make install

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I am Vitalijus Ryzakovas. This is my LINUX/UNIX blog.

Monthly Archives: May 2015

docker centos 7.1 systemd

selinux policy modules

custom java enviroments

linux alternatives

wget java

fedora join active direcroty

linux check if process is running send mail

apache syn flood

linux add (allow) more ports

allow a range of ports in iptables

checking for libmemcached location… configure: error: Unable to find memcached.h under

nf_conntrack: table full, dropping packets

decking create docker cluster simple

bash menu box

build qemu from source