The Queen and 11 Presidents!
Queen Elizabeth II head of the Commonwealth and daugher of George VI. She was born on 21 April 1926 and have seen lot of politics and historical acts in her life, because now she is 84! As her father dies in 1952, she become the Queen regnant an met 11 Presidents of United States till now:
Sending Mails with own Exim: Google account example.
Today I’ll describe short, how to configure sending of emails with your Debian or other Linux distribution. The ability of sending mails is very useful feature for every long-running server machine, it’s easy and common way to notify the administrator on problems.
Here are configurationsteps for mail-sending with Exim and Googlemail account (google Apps accounts work the same way too).
- first of all we need working Exim. If not installed – install exim4.
$ apt-get update $ apt-get install exim4
- Configuration should start after the installation. However you can start configuration of exim every-time with
$ dpkg-reconfigure exim4-config
- Answer the questions of configuration wizard. The important one is.
a general type of mail configuration. Choose “sent by smarthost”
if you wanna use the ability of e.g. Googlemail account. Then SMTP with dynamic IP would be difficult
- answer other questions
- Provide a System Mail Name: e.g. mycompany.com
- Provide IP addresses to listen on for incoming SMTP connections User 127.0.0.1 if you don’t want only send mail from local machine and nothing for all IP’s.
- Provide Machine handling outgoing mail for this host (smarthost): smtp.gmail.com::587
- Now it’s time to provide credentials information of your gmail account. Therefore you need edit /etc/exim4/passwd.client file with your favorite editor.
Insert that for Standard or google app account but replace with valid mail and password.
gmail-smtp.l.google.com:yourYourMail@googlemail.com:yourPass *.google.com:yourYourMail@googlemail.com:yourPass smtp.gmail.com:yourYourMail@googlemail.com:yourPass
- Make sure /etc/exim4/passwd.client belongs to user root and group Debian-exim which is normal so on my Debian. If not, run that command:
$ chown root:Debian-exim /etc/exim4/passwd.client
- Actualize the whole configuration with:
$ update-exim4.conf
Your ‘re done!
echo "Server Mail Test Message " | mail -s "Just Test" SomeMail@someDomain.orgWatch logs:
$ tail -1000f /var/log/exim4/mainlogWhen you see something like this. Everything should vent perfect.
2010-02-14 23:00:26 1NgmVu-0007v8-Kt < = root@mail-server1.mycompany.com U=root P=local S=424 2010-02-14 23:00:28 1NgmVu-0007v8-Kt => testMail@mycompany.org R=smarthost T=remote_smtp_smarthost H=gmail-smtp-msa.l.google.com [72.14.221.109] X=TLS1.0:RSA_ARCFOUR_MD5:16 DN="C=US,ST=California,L=Mountain View,O=Google Inc,CN=smtp.gmail.com"
Winter amusement – the Russian way
What should young people do at a long, cold, rich of snow and boring winter. A winter like in Magadan town.
Here the answer
Never heard of Magadan? Magadan is associated with far far east of Russia. It is associated with cold and people-less places, taiga, beautiful nature and interesting people. Of course this Region is famous for former Soviet GULAGs too.
SSH tunnel without password
SSH (Secure Shell) allows simple establishment of encrypted and authenticated connection between computers. Today i describe how easy it is do establish such SSH tunnels without using a password. You may need such connections when they have to be opened by daemons (e.g. Cron) without user interaction.
Two words on theory. Password-less connections have to be authenticated at least so strong like the password enabled one, so asymmetric cryptography which enables certificates comes into play. The clue is to have private and public keys and share your public key with domains which should be able identify you.
So therefore let’s start by generation a needed key-pair.
Generating Keys
It is possible to create key with pass-phrase and without (or empty pass-phrases). I prefer to not use pass phrase because it is asked every-time on later usage of a ssh. Even there are ways to gives the pass-phrase to ssh command, but it is more work, with no significant security benefits. So i do the following statement and do not enter any pass-phrase (just hit enter on question).
$ ssh-keygen -t rsa
This will create RSA key-pair as following files in ~/.ssh directory:
- id_rsa
- id_rsa.pub
Transfer Public keys
The best way to do it is to use ssh-copy-id program which is inside of many linux distributions.$ ssh-copy-id -i ~/.ssh/id_rsa.pub remote-user@remote-server.orgIn that case everything is done automatically and you are ready after that. But if ssh-copy-id is not available, you can copy keys manually e.g. like that.
$ cat ~/.ssh/*.pub | ssh remote-user@remote-server.org 'umask 077; cat >>.ssh/authorized_keys'Attention! On some linux distrs SSH2 searches for keys in ~/.ssh/authorized_keys2 . Not so in actual Debian (Lenny), but seems to be so in SuSe linux.
Test
Now remote login, scp and sftp can be used without password. Test it:# establish connection $ ssh remote-user@remote-server.org #or copy files secure and password-less. $ scp /home/user/some-file remote-user@remote-server.org:/some-path/dir/More information on SSH related man pages.
JBoss 5 GA on Debian linux
This short tutorial describes how to configure JBoss Application Server (Jboss GA 5.1.0) on a debian linux (Debian GNU/Linux 5.x “Lenny” ). Article starts with installation of java JDK and continues with JBoss installation and basic configuration according to standard file system hierarchy. Also init.d. scripts configuration is given here.Installing Java SDK
Nowadays installing Java environment on Debian is an easy task. I used JDK 1.6. Don’t confound JDK with JRE, because bare Java Runtime Environment is not enough for running JBoss. Debian Wiki maintains (hope) a list of available java .deb packages, which are easily can be installed with your preferred way. I prefer aptitude, but apt-get of course works too.$ aptitude install sun-java6-jdk #or by good old apt-get. $ apt-get install sun-java6-jdkInstallation is done after seconds. Now test your java installation with
$ java -version # Here example result on my configuration: java version "1.6.0_12" Java(TM) SE Runtime Environment (build 1.6.0_12-b04) Java HotSpot(TM) 64-Bit Server VM (build 11.2-b01, mixed mode)If you get something like this, you’re done and your java should be already in the PATH.
Installing JBoss AS
Now let’s install JBoss Application Server.Preparing
Normally you are not willing to start services (especially when they are accessed from outher machines) with root privileges. Therefore we have to define new user and group which will be used to manage JBoss. So next line will create new group and new user with this group.
$ groupadd jboss $ useradd -s /bin/bash -d /home/jboss -m -g jboss jbossThis jboss user has no password, so nobody can login with this username. If you consider to login with jboss user, password has to be set. Use passwd jboss command for that.
Download, Installation, filesystem layout
Now download desired Jboss version. I started with JBoss 5.1.0 GA, which can be download with:$ cd /tmp # swithch to temp dir $ wget http://sourceforge.net/projects/jboss/files/JBoss/JBoss-5.1.0.GA/jboss-5.1.0.GA.zip/downloadCheck also the whole list of verisons if interested. As you may noticed JBoss binaries are packaged with ZIP. So it is comfortable to use unzip tool. Maybe you have to install it first. But before you extract downloaded file, we have to decide, where exactly should JBoss files be placed on a file-system. Unfortunately JBoss is not quite conform to Linux File System Hierarchy Standard per default, so there are many possibilities for a location configuration. Some of you may want to place JBoss into /opt directory. But I prefer to split the installation a little bit and want to start by putting JBoss core files in /usr/local/, where local, unchangeable and read-only files usually placed. E.g. I use /usr/local/jboss/510 as JBoss 5.1.0 GA root. So let’s create that location and extract files into it.
mkdir /usr/local/jboss #create new jboss directroy chown jboss:jboss /usr/local/jboss #now its belongs touser jboss and group jboss su jboss mkdir /usr/local/jboss/510 cd /usr/local/jboss/510 unzip /tmp/jboss-5.1.0.GA.zipAt this moment you should have new working JBoss. If you want, test it with
bin/run.sh -b 0.0.0.0Where -b 0.0.0.0 means that JBoss is listening for every ip address of current machine. However at this stage the installed Jboss still brakes the Linux Filesystem Hierarchy Standard, so let’s improve this situation.
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Software RAID on Debian Linux
Wow, my last post here is month ago. But don’t worry I did not forget about my blog. There are just many thing happened in my life, all of them are time consuming
So there no reason to remove me from your RSS reader. Today i will share some thought on software RAID under linux with you.
RAID 1
Some days ago i installed RAID 1 on Debian Lenny (amd64 arch) without any troubles for now.
I just was following Jerry’s description which is enough detailed to make no mistakes except maybe one thing.
The Partitions used in the RAID /dev/md0/ should both enable boot flag if you want to boot from RAID.
This is worked for me.
Configuration
My configuration is the same as Jerry’s except partition sizes and chosed LVM. So boot is done form RAID partition /dev/md0. And SWAP is on RAID too, which is controversy solution but it the best one for me, of course availability of a system is primary goal. So how to check the state of raid after installation. The simplest is to look on /proc file-system with $cat /proc/mdstat. Here is my configuration.$cat /proc/mdstat Personalities : [raid1] md1 : active raid1 sda2[0] sdb2[1] 476560128 blocks [2/2] [UU] md0 : active raid1 sda1[0] sdb1[1] 497856 blocks [2/2] [UU] unused devices: <none>Here you see two RAID arrays md0 and md1. Also information about used devices and state are peresent. [UU] stand for “used” for every disc is used in a raid. On diskfailure you wold see something like [U_] and sdb2(F). Next example utilizes mdadm which is used by kernel in latest kernel versions. My is 2.6.26-2-amd64 (lenny default) Use of –detail or -D option with a device name gives more information. Here my example.
# mdadm --detail /dev/md1 /dev/md1: Version : 00.90 Creation Time : Wed Jan 6 00:51:37 2010 Raid Level : raid1 Array Size : 476560128 (454.48 GiB 488.00 GB) Used Dev Size : 476560128 (454.48 GiB 488.00 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Mon Jan 11 02:18:01 2010 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 UUID : fe3bbbfd:2c6963e7:9785a408:be715448 Events : 0.8 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 1 8 18 1 active sync /dev/sdb2
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Eclipse Ganymede and WSCompile incompatibility?
I found strange problem with WSCompile-1.6 task in Ganymede release of Eclipse (Version 3.4.1). The problem lies in WSCompile-Ant-Task. Buildscript execution freezes on the wscompile task. I describe that problem more detailed on techjava.de Please feel free to comment here or there if you know what died changed in Ganymede in ant scripts handling since Europe release and how to fix it.Extracting tar, gzip, bzip2, z
Sometimes you need to extract some files on Linux console. Here some examples how to do that.
tar
Tar archives are the most common way of distributing bundles of files under Linux or UNIX. A .tar file is simply a bundle of files packaged with GNU tar program. To extract such files use following:tar xf somearchive.tar tar xvf somearchive.tar
- Provide option f if you want to extract content of files. Tar (from tape archive) has long history and was intended to work with tape media, so when you omit f tar tries to work with tape device.
- v- stands for verbose. List all the files by extract process.
- x- Extract command
tar tf archive.tarFor more tar parameters see Man pages.
gzip
Often tar-files are also compressed. One of the most known compressed formats is GNU Zip (gzip). Tar bundeld and zipped file would normally have extension .tar.gz. To extract such files you can use tar with “z” option, which causes tar to automatically invoke gzip. Modify abow example and you get able to extract tar.gz files too.tar -xzf somearchive.tar.gzIn old tar version the “z” option is may be not available. In that case just use UNIX pipes:
gzip -dc target.tar.gz | tar xf -Meaning of gzip options
- d – Do decompress!
- c – write to console (So that tar can take it from there )
- t – Tests file integrity
- l – lists archive file information
bzip2
Sometimes you can find files ending with .tar.bz2. That are files packaged with bzip (a block-sorting file compressor). Use it like gziptar xjvf filename.tar.bz2Options d,c,t have the same meaning. More on Man pages.
zcat
Some files have .tar.Z endings. They can be extracted byzcat somearchive.tar.Z | tar xf -Look in Man pages for more. Any questions? You are welcome to comment!