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Archive for the ‘Linux’ Category

RHEL / CnetOS 7 sftp logging in chroot

January 21st, 2015 No comments

To have idea whats going on with internal-sftp when you have chrooted users, this is the way how to enable logging for internal-sftp for RedHat 7 or CentOS 7.

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Midnight Commander UTF8 line drawing characters problem

March 24th, 2014 No comments

As UTF8 encoding is by default installed/enabled in RedHat Enterprise Linux 6.5 / CentOS and similar distros, it drives me mad to have weird line characters in terminal when I logged in via SecureCRT/Putty due UTF-8 encoding. Read more…

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How-To disable IPv6 on RHEL6 / CentOS 6 / etc

March 14th, 2013 14 comments

Proper way of disabling IPv6 subsytem in RedHat Linux 6 / CentOS 6 (dont unload modules or so)

in /etc/sysctl.conf  :  net.ipv6.conf.all.disable_ipv6 = 1

in /etc/sysconfig/network  : NETWORKING_IPV6=no

in /etc/sysconfig/network-scripts/ifcfg-eth0 : IPV6INIT=”no”

disable iptables6 – chkconfig –level 345 ip6tables off

reboot

done 😉

PS: if you have more eth interfaces, use brain 😉

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Shrink Thin disk in ESX 5 (jelly-shot)

March 11th, 2013 No comments

just summary 😉

  1. fill with zeros empty space in runing VM OS
  2. Windows – SDelete from Sysinternal LINK
  3. Linux – fill up each mount point/partition with command
    dd if=/dev/zero of=ZEROFILE bs=1000000 ; rm -f ZEROFILE


  4. Check real size of allocated data in VM

    du -h MyVM.vmdk


  5. From ESX shell , run command to shrink vmdk disk (shutdown VM first)
    vmkfstools --punchzero MyVM.vmdk
  6. Check real size of allocated data in VM after (should be less)

    du -h MyVM.vmdk


  7. log off
  8. If not Thin provisioned disk, use another post 😉
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Migrating ESX Thick disk to Thin disk (ESX 5.1 is always special)

March 11th, 2013 2 comments

So,  in previous article I cleanup Linux virtual machine , zeroed all empty space. Thick file is 42 GB, lets see how it big I can make it.

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Shrink Thick Linux virtual disk (vmdk) in ESX

March 11th, 2013 No comments

I have thick provisioned server, and I need move it and shrink it. As Thick option provides flat file of full size , even if OS is few GB, I have full size vmdk file ;( which is harder to copy around.  Thin provisioned vmdk disk is possible shrink via ESX shell command ( vmkfstools –punchzero *.vmdk) but what to do if disk is in Thick state ? Its possible, but little bit more complicated.

Excellent post to explain in depth dafuq – http://blogs.vmware.com/vsphere/2012/03/thin-provisioning-whats-the-scoop.html

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Brute force attack Dovecot IMAP server – blocking IP with TCP wrappers

March 5th, 2013 No comments

Trying brute force login to Dovecot IMAP server is happenning, log is filling up ;(

Lets block it 😉

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RedHat RHEL 6 system wide proxy settings

April 27th, 2012 3 comments

When you need to have proxy connection available to whole system, so dont bother with settings for firefox, yum proxy and similar, its simple as just plain file 😉

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Linux “find” cheat sheet

April 16th, 2012 No comments

Some collection on various find tasks I experienced from time to time. Find is powerfull tool, often overlooked, but its lifesaver. Enjoy, if you have something more, please, share in comments.

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Short: SFTP chroot for user to web root

November 9th, 2011 No comments

I needed sometimes to grant access to web root for developer/friends and don’t want to  allow them “chillout” thru directories Winking smile . Here is sample how to setup SSHD server to allow sftp connection and chroot it to home directory – basically lock user via SFTP to Virtual Home for web server.

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