Evaggelos Balaskas - System Engineer

The sky above the port was the color of television, tuned to a dead channel

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Dec
23
2010
postfix & recipient bcc aka Automatic BCC recipients
Posted by ebal at 17:28:05 in planet_ellak, planet_Sysadmin

I am supporting a greek company with two linux servers.
These two linux boxes have a lot of services,
including a mail server and they are set upped as active/passive.

In the past week they lost their internet adsl connection.
This is a true and horrible story, but for that i’ll write another post in near future.
So without an internet connection there werent a lot of things i’ve could do.

Thanks to Santa Claus i had predict this problem and i have installed a linux vps server outside of the company as a backup mx/mail server to queue all the undelivered mail.

From the company, i ‘ve been asked if i could keep all the mails in queue and also provide a copy to a gmail account. After google searching about postfix rewrite and re-queue i ‘ve came to automatic recipient bcc.

In my /etc/postfix/main.cf (or you can use postconf) i added this line:


recipient_bcc_maps = regexp:/etc/postfix/recipient_bcc_maps

If you are a careful reader then you have noticed that i wrote regexp for my recipient map file.
And the reason is that i wanted to combine all the mails that came to the backup mx server.

This is my /etc/postfix/recipient_bcc_maps:


/@example.com/       example.com@gmail.com

Of course i had to reload postfix in the vps and send a test email to verify that the blind copy for all the domain is working.

If you want to re-queue all the mails then you have to do something like this:


postsuper -r ALL

PS: As the Journey have said: Don’t Stop Believing …. in Santa Claus
Have a nice holiday :)

  • 1 comment
Dec
15
2010
Convert mdf/mds image to iso
Posted by ebal at 19:46:32 in planet_ellak, planet_Sysadmin

This time, only code and no comments:

installation


git clone git://git.berlios.de/iat iat.git
cd iat.git
./autogen.sh
./configure
make

sudo make install

Usage


$ /usr/local/bin/iat -i image.mdf --iso

RAW Block :2352
 100% [:=====================:]

Verification


$ file image.iso 
image.iso: ISO 9660 CD-ROM filesystem data 'image'
Dec
15
2010
the stupidity of online services
Posted by ebal at 19:16:52 in planet_ellak, planet_Sysadmin

A long time ago, i had created an account on a site to use their online service
(the site/company and the service is irrelevant to this story).

This evening i had to use this service again, but i couldnt remember my password!
Thats not a problem, i hit “You forgot your password” button and i followed their instructions.

Just a few clicks and some seconds ago, i was reseting my password to something new.

So i ‘ve tried the login page on the site.

Email or password incorrect.

My first thought was, that i had misspelled my password on the reset form.

I did the reset procedure once again.
This time i wrote the password to an empty text file (just to be sure) and i copied the password from the text file to password & rewrite password text field on the reset page.

After that and one more time:

Email or password incorrect.

So i clicked “support & help, follow this link”.

Thats nice …..

To use their support & help & faq & whatever else they have, i must logon to their site!

HELLLOOOOOO guys

i have problem with your fuc@#$@#$ login page,
how on earth i can login to your help page to open o fuc@#$@# ticket when
my problem is your login page !!!

The Horror! The Horror!

why people are so stupid ?

Dec
12
2010
hackfest2: the return of hack-elves
Posted by ebal at 10:06:17 in planet_ellak

Μπορεί να έχει λίγο κρύο, αλλά έχει βγάλει ήλιο.
Είναι όμορφα εκεί έξω.

Οπότε πάρτε το laptop σας κι ελάτε να πιούμε καφέ ή ζεστή σοκολάτα μαζί μας στην πλατεία εξαρχείων.

Ελάτε να δουλέψουμε μαζί στα αγαπημένα μας project.

Να ανταλλάξουμε ιδέες και να μοιραστούμε γνώση.

hackfest2: the return of hack-elves

Dec
09
2010
linuxgazette
Posted by ebal at 20:22:55 in planet_ellak

Ένα από τα online περιοδικά που διαβάζω, είναι το linux gazette. Τους τελευταίους μήνες, μετέφεραν υπηρεσίες κι άρθρα σε νέα μηχανήματα. Αποτέλεσμα αυτού, ήταν να βρεθούν αρκετοί mirrors, out of sync!

Από ότι έμαθα, αντιμετώπισαν πολύ σημαντικό πρόβλημα με την υπηρεσία rsync. Για αυτό και οι ελληνικοί mirrors είχαν προβλήματα ανανέωσης.

Πλέον όμως, σχεδόν όλα τα προβλήματα έχουν επιλυθεί. Για όσους δεν γνωρίζουν το περιοδικό, ας ρίξουμε μια ματιά.

Dec
09
2010
ftp.otenet.gr
Posted by ebal at 20:03:56 in planet_ellak

Βρήκα την πλήρη λίστα με τα προγράμματα που κάνει mirror ο http://ftp.otenet.gr:

apache
archlinux
centos
cpan
debian
debian-non-US
fedora-linux-core
freebsd
gnu
internet-drafts
kde
kernel
linuxgazette
mozilla
mozilla-firefox
mozilla-thunderbird
openbsd
postfix
redhat
redhat-contrib
redhat-rawhide
redhat-updates
rfc
samba
sidux
slackware
squid-ftp
squid-www
tucopy
tucows
tucows-bsd
tucows-games
tucows-html
tucows-html2
tucows-linux
tucows-mac
tucows-office
tucows-pda
tucows-themes
tucows-tukids
tucows-unixthemes
ubuntu
ubuntu-releases
vim
winsite

Dec
09
2010
Famous Why Interview
Posted by ebal at 17:56:20 in planet_ellak, pirsynd, planet_Sysadmin

No so long ago, i’ve noticed that pirsyncd published (not by me) in download.famouswhy.com . I have to say that i didnt know about this site. But the people behind it, have found me and asked me a few questions. So here is my first interview about me & pirsyncd.

Nov
22
2010
python3 http server
Posted by ebal at 07:52:10 in planet_ellak, planet_Sysadmin

When i want to setup a simple http server, i use python with SimpleHTTPServer module.
But in python3 this module is been merged with http.server.

So if you are using python 3, then you should use something like this:

python -m http.server

If you want to use a high port (perhaps you are a simple user) then type something like this:

python -m http.server 8888
Nov
21
2010
hackfest1 Its alive !
Posted by ebal at 09:47:34 in planet_ellak

Καλημέρα, το hackfest1 είναι πλέον γεγονός.
Ο κόσμος έχει αρχίσει να μαζεύεται σιγά σιγά,

κι έχουμε ήδη ανοίξει το κανάλι στο freenode για να μπορεί ο κόσμος να συμμετέχει απομακρυσμένα:

#hackfestgr στο freenode
Nov
17
2010
Permit ssh access to your cisco router only from your internal lan
Posted by ebal at 22:25:58 in planet_ellak, planet_Sysadmin

If your internal lan is: 192.168.0.0/27

First create a new access-list:

access-list 123 permit ip 192.168.0.0 0.0.0.31 any

and then add this to your line configuration:

access-class 103 in

If you want more help:

€ ssh ROUTER_IP
 password: 

router>en
Password: 

router#conf t 
Enter configuration commands, one per line.  End with CNTL/Z.

router(config)# access-list 123 permit ip 192.168.0.0 0.0.0.31 any

router(config)# line vty 0 4
router(config-line)# access-class 103 in
router(config-line)# end

router# write mem

  • 1 comment
Nov
16
2010
plesk & iptables
Posted by ebal at 19:54:59 in planet_ellak

Μία βεβιασμένη κίνηση για την προσθήκη μίας IP στο firewall του plesk και βρέθηκε ο web server μου “κλειδωμένος” πίσω από το iptables:

Deny incoming from all on all ports

Κι όλα αυτά γιατί στο 1ο κουτάκι, που έπρεπε να γράψω το όνομα του rule, έγραψα την IP!!!
Κι επίσης είχα επιλέξει το DENY !

pleskiptables.jpg

Nov
12
2010
The Evolution Of The Geek
Posted by ebal at 12:03:53 in planet_ellak, planet_Sysadmin

ft-geek-10-20-1.jpg

  • 1 comment
Nov
11
2010
Impove your dns queries (also your traffic) with resolv.conf
Posted by ebal at 19:54:17 in planet_ellak, planet_Sysadmin

This post is just a suggestion! Not real data or benchmarks are been provided !

I was reading the manual page of resolv.conf. Yeap thats true, i am that kind of people that are reading manual pages before bed time.

man 5 resolv.conf

or alternative read this: resolv.conf.

I only use nameserver, domain and search configuration options on my resolv.conf, but reading the manual page,i ‘ve read about rotate option.

With this option our machine run queries with a round robin mechanism on our nameserver declarations.
That means that if you are using two dns cache servers in a big infrastructure, we can query both dns servers equally improving the load average on our dns machines.

If you have more, even better.

So give it a try

Nov
07
2010
Xfce 4.8pre1 Released
Posted by ebal at 18:37:25 in planet_ellak, xfce, planet_Sysadmin

The Xfce development team is proud to announce the first preview release for Xfce 4.8. Together with this preview release, the Xfce project announces the feature freeze for the final 4.8 release which is set to be pushed out to the world on January 16th, 2011.

Read the full news release here: Xfce 4.8pre1 Released

Nov
05
2010
Προκηρύξεις θέσεων εργασίας στον ΟΤΕ
Posted by ebal at 17:28:55 in planet_ellak

Ο ΟΤΕ έχει αναρτήσει θέσεις εργασίας.

OTEGR - nees_theseis_ergasias

http://jobs.ote.gr

Μα δυστυχώς το μόνο μήνυμα που θα δείτε είναι το εξής:

Η σελίδα απαιτεί τη χρήση Microsoft Internet Explorer έκδοση 6 ή νεότερη.

Δυστυχώς οι διαχειριστές του ote jobs portal βρίσκονται ακόμα στην λήθη.
Με αρκετό ψάξιμο βρήκα τα εξής:

http://jobs.ote.gr/jobsdocs/OTE2010115124831.doc
http://jobs.ote.gr/jobsdocs/OTE2010115124545.doc
http://jobs.ote.gr/jobsdocs/OTE2010115124427.doc

Δλδ ούτε καν σε pdf μορφή!

Κρίμα, πολύ κρίμα.

  • 4 comments
Oct
21
2010
vodafone sucks
Posted by ebal at 09:58:46 in planet_ellak

Τον τελευταίο μήνα δέχομαι συνεχώς τηλεφωνικές κλήσεις από την vodafone. Εκτός ότι είναι ενοχλητικοί (με παίρνουν δύο με τρεις φορές την βδομάδα) δεν δέχονται το γεγονός ότι ΔΕΝ έχω καμία επιθυμία να μεταβώ στην vodafone. Δεν ξέρω σε ποια εταιρεία έχουν δώσει το call center, αλλά φτάνει πια. Κύριοι ΔΕΝ ενδιαφέρομαι, ποτέ δεν ενδιαφερόμουν και με αυτή την συμπεριφορά ΔΕΝ πρόκειται ποτέ στην ζωή μου να ενδιαφερθώ. Είστε ενοχλητικοί και έχετε ξεπεράσει κατά πολύ τα όρια του spam. Οι συνεχής κλήσεις από “άγνωστο αριθμό” και παρότι την αρχική μου δήλωση είπα ότι δεν ενδιαφέρομαι είναι πλέον εκνευριστικές. Εάν είχα vodafone θα άλλαζα εταιρεία μόνο και μόνο για το απαράδεκτο call center. Όχι ότι αυτό θα σταματούσε τα συνεχή τηλεφωνήματα, αλλά δεν θα είχα καμία μα καμία συμμετοχή στο να πληρώνονται αυτοί οι άνθρωποι από τα δικά μου χρήματα.

  • 1 comment
Oct
18
2010
hackfest0
Posted by ebal at 10:34:47 in planet_ellak

Εχθές έγινε το 1ο hackfest event στο καφέ/βιβλιοπωλείο Floral στην πλατεία των Εξαρχείων. Περίπου είκοσι (code) hackers μαζεύτηκαν να ανταλλάξουν απόψεις/ιδέες και να μιλήσουν περί κώδικα και projects με τα οποία ασχολούνται. Erlang, closure, lisp, ruby, python & java ήταν μερικές από τις γλώσσες που ασχολήθηκαν οι συμμετέχοντες. Εντυπωσιακό, επίσης, ήταν να βλέπεις ανθρώπους να ασχολούνται με Arduino, openwrt αλλά και με τον σχεδιασμό ηλεκτρονικών πλακετών!

hackfest

Εάν και είχαμε κλείσει τον χώρο από τις 11.00 μέχρι τις 15.00, διαπιστώθηκε ότι ο χρόνος ΔΕΝ μας έφτανε!
Έχουμε ήδη ξεκινήσει να σκεφτόμαστε πότε και που θα είναι η επόμενη συνάντησή μας.

Έχουμε αρκετές ιδέες, αλλά θέλουμε και τις δικές μας.

Έχουμε δημιουργήσει κι ένα linkedin group: hackfest για όσους θέλουν να συμμετέχουν.

Σας περιμένουμε λοιπόν στο επόμενο hackfest, μην ξεχνάτε το motto μας:

Open ideas for intelligent people !

Oct
13
2010
Creating Custom Command in vi
Posted by ebal at 11:27:54 in planet_ellak, planet_Sysadmin

I am using vi for almost everything, and i always comment before my changes. I prefer to comment like this:

# ebal, Wed Oct 13 14:20:46 EEST 2010

so i usually type:

i
# ebal,
esc
: r! date

I was loosing too much time with that, so i’ve searched in google for a custom shortcut in vim to do exactly the above by hitting a special key.

After a while i found the solution!

In the end of /etc/vimrc i put the below map vi command:


:map <f1> :r! export -p LC_ALL=C; echo "# `whoami`, `date`"<return>
  • 2 comments
Oct
13
2010
hackfest0: booting up [17.10.2010]
Posted by ebal at 10:45:39 in planet_ellak

Μην ξεχάσετε, αυτή την κυριακή στις 11.00 το πρωί:

hackfest0-booting-up-17-10-2010

Oct
12
2010
Swapoff will make faster my linux box ?
Posted by ebal at 06:36:16 in planet_ellak, planet_Sysadmin

Yes and no …

The swap partition is an extended memory. Newest kernels are reserving the entire ram at start so when an application needs more ram, swap partition is here for us. But what if our swap partition is full ? That cannot be done cause there is a percent that kernel is using for the swap partition. This kernel value is described here:


cat /proc/sys/vm/swappiness

In most linux systems the default value is 60 percent.
In virtual machines we should reduce this percent to something small cause of IO limitations.
In our desktops we can increase it, to even higher values.

But what if we need more ram, more swap ?
What if our applications are running all together and the swap partition is in its limits ?

Then just … swapoff !!!

With swapoff the system will drop the swap partition!
But how this is more helpful ?

It isnt !

swapoff frees up unused memory and we can change the value of swappiness to something higher, lets say:


sudo sysctl -w vm.swappiness=80

And then swapon the swap partition again …

If we need to make a permanent change for the swappiness, we need to make it to /etc/sysctl.conf

  • 2 comments
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