• Vbox Virtualbox DNS NAT Network Mode NOT working


    There is a random bug that sometimes occurs with Vbox NAT mode DNS, although it has never happened in the past and Vbox was working fine until recently. The symptom is that you can see it does get an IP+ DNS from the Vbox NAT DHCP. Below we use resolvectl dns and verify the DNS server is set to 10.0.2.3 which is the DNS from Vbox NAT. We can ping it but it does not respond to any DNS requests when we use dig @10.0.2.3 realtechtalk.com........
  • Ubuntu/Debian Linux/Unix Howto Setup Install Syslinux Bootable USB with EFI and MBR from Command Line/CLI Terminal


    There aren't too many simple guides that show you how to use commands to setup your USB or other drive as a normal bootable drive where you can easily boot custom kernels or whatever OS you would like. 1. Get the tools we need: We install "syslinux" for MBR and "syslinux-efi" for EFI and "MBR" as we need a tool that embeds the actual MBR into our USB: sudo apt install syslinux syslinux-efi mbr........
  • Postfix How To Change Sending IP Address To Specific IP Binding or Interface


    Ithought I'd post this becuase there is some bad information out there. Some guides tell you to edit /etc/postfix/master.cf (-o smtp_bind_address=) but this doesn't work. The same guide also says if you don't change it there you end up changing the listening IP/bind interface which is also not true. Here is a simple and effective way to change Postfix's sending/binding/outgoing IP address (very important for reverse DNS and so mail servers don't block you)........
  • How to qemu-kvm enable bridged networking in Debian Ubuntu Linux Mint on KVM containers


    I've read a few guides about this but they didn't work for me. sudo apt-get install bridge-utils #don't think the above is enough it won't work still even though you have by default an /etc/qemu-ifup that handles it if you have the right tools and setup sudo qemu-system-x86_64 -net tap -net nic -enable-kvm -cpu host,vmx=on ~/VirtualBox VMs/vsphere-vcenter/vsphere-vcenter.vdi W: /etc/qemu-ifup: no bridge for guest interface foun........
  • Centos 7 How To Change Hostname


    Some guides still use the old Centos 6 style (do not use /etc/sysconfig/network). In Centos 7 the file is /etc/hostname echo "HOSTNAME=yourhostname.com" > /etc/hostname........
  • Migrate Centos 7 from Single HDD to mdadm RAID 10 array:


    Done on Centos 7.3 very important as clearly based on older guides it was a lot easier and more simpler! Hint do not use grub2-install! If you have trouble booting after this check this CentOS mdadm RAID booting/fixing guide. One huge caveat if you are an oldschool user or sysadmin who has avoided UEFIbooting The nor........
  • Webalizer Error Error: Unable to restore run data (11) Error: Unable to restore run data (11) Solution


    Error: Unable to restore run data (10) Error: Unable to restore run data (11) Ikeep getting this error but so far there is no obvious solution. Sometimes I've had to remove the *.hist files so I'll try that again. *Update This is an ongoing random problem after months of running webalizer it runs into some problem that can only be fixed by removing the following files so it can rebuild the stats (you end up losing p........
  • Howto Convert Xen Image to KVM


    #count=10000 makes an image of 10000MB make sure your image is at least the same as your existing dd if=/dev/zero of=yourimage.img bs=1M count=10000 # losetup -fv newimage.raw # fdisk -cu /dev/loop0 # kpartx -a /dev/loop0 # dd if= of=/dev/mapper/loop0p1 # e2fsck -f /dev/mapper/loop0p1 # resize2fs /dev/mapper/loop0p1 # a lot of guides tell you to edit /etc/fst........
  • How to Encode all VOBs from a DVD/Bluray VIDEO_TS folder into an XVID


    In my case I already copied the VIDEO_TS folder to my hard drive. Here is the command for mencoder: mencoder -dvd-device "myvideobackup/VIDEO_TS" dvd:// -ovc xvid -oac mp3lame -lameopts cbr:br=128 -xvidencopts pass=2:bitrate=-700000 -o myvideobackup.avi Replace "-dvd-device myvideobackup/VIDEO_TS" with the location of your backup files or the /dev device of your DVD drive. The -o myvideobackup.avi is of course the name o........
  • Enable SPAMASSASSIN on Postfix in 5 minutes


    Centos 5 Postfix and SPAMASSASSIN Tutorial yum install spamassassin chkconfig spamassassin on vi /etc/mail/spamassassin/local.cf ############## #required_hits 5 #report_safe 0 #rewrite_header Subject [SPAM] #5 is the least restrictive (means only the most obvious SPAM is caught. 0 is obviously the most restrictive/sensitive and would have lots of false positives require........
  • chroot into an off-line Linux version using a LiveCD/USB


    It's not just as simple as running the chroot command, you need to ensure the /proc and /dev entries are passed through and populated to the chroot environment. Step 1 - Mount Your Off-lineOS mount /dev/sda1 /mnt Step 2 - Mount Proc mount -t proc none /mnt/proc Step 3 - Mount Dev Most guides will tell you to use this: mount -o bind /dev /mnt//dev but that doesn't work for some reason in many cases: mount: wron........
  • SSH Automatic/Passwordless Logon - Setup Public Key Encryption In Single Command


    This is a very simple solution, but most guides out there make you login twice (once to scp the key) and once to put the key in authorized_keys. There's no need for that. If you don't already have a ~/.ssh/id_rsa.pub just type "ssh-keygen -t rsa" and keep hitting enter until it's done :) Just use this code to easily enable passwordless login with SSHD key=`cat ~/.ssh/id_rsa.pub`;ssh user@192.168.5.25 "echo $key >> ~/.ssh/auth........
  • My list of handy security links - Ongoing


    My list of handy security links - Ongoing[b:6f8d25be68][size=18:6f8d25be68]News[/size:6f8d25be68][/b:6f8d25be68] Security Focus http://www.securityfocus.net - Nice Security News Site CERT http://www.cert.org/ Common Criteria (see if your OS/software is EAL4 certified) EAL(Evaluation Assurance Levels is the industry standard for evaluation of security in software) http://www.commoncriteria.com [size=18:6f8d25be68][b:6f8d25be68]Tools[........
  • Configuring OCFS2 Clustered File System on Debian Based Linux including Ubuntu and Kubuntu


    There's a lot of information and guides on OCFS2 for RHELand Centos Linux but the package setup and configuration is slightly different and this has thrown some people off. Installing OC2FS You should install the following packages to get started: apt-get install ocfs2-tools ocfs2console Configure OC2FS In RHEL/Centos the main configuration file is located in /etc/sysconfig/o2cb However in Debian based Linux it is located........
  • Viewing and Connecting to an SMB Samba Share on Windows/Linux/Unix


    This will give you the basic info needed to browse and connect to Samba shares from the command line. From the GUI of Gnome or KDE etc, it is pretty standard and straight forward. However, I've found very little guides on how to do it from the command line and if you're like me, a nerd who prefers command line for its simplicity and for remote use, this is the way to go. First get a list of all the Samba/SMB shares on the target. smbclient -L hostname........
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