VirtualTam's bookmarks

1. AWS | Enable Enhanced Networking with Elastic Network Adapters for vintage OS AMIs 2019-09-17

   tags: chroot, cloud/aws, linux, linux/debian, linux/kernel, virtualization, xen

   [ permalink ]

   Paravirtual (PV) to Hardware Virtual Machine (HVM):

   • https://stackoverflow.com/questions/24330721/amazon-ec2-how-to-convert-an-existing-pv-ami-to-hvm

   ENA support:

   • https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking-ena.html
   • https://forums.aws.amazon.com/thread.jspa?threadID=166135
   • https://aws.amazon.com/premiumsupport/knowledge-center/boot-error-linux-m5-c5/
   • https://bugs.centos.org/view.php?id=14107
   • https://ygrene.tech/how-to-enable-ena-support-for-aws-amis-in-5-steps-and-make-your-bamboo-remote-jobs-really-fast-f2a4254a9955

   Build Debian AMIs from scratch:

   • https://bootstrap-vz.readthedocs.io/en/master/
   • https://github.com/andsens/bootstrap-vz
   • https://www.slideshare.net/JamesBromberger/debian-cloud-building-the-debian-amis
   • https://blog.james.rcpt.to/2012/12/06/official-debian-images-on-amazon-web-services-ec2/

   Squeeze:

   • https://lists.debian.org/debian-cloud/2013/02/msg00023.html

   Wheezy:

   • https://lists.debian.org/debian-cloud/2014/10/msg00009.html
   • https://lists.debian.org/debian-cloud/2014/11/msg00000.html

   Boot to chroot:

   • https://unix.stackexchange.com/questions/85714/boot-into-a-chroot
   • https://wiki.debian.org/chroot
   • https://wiki.debian.org/Debootstrap
   • https://superuser.com/questions/384437/booting-linux-system-from-chroot-is-there-a-better-way-to-do-this/384457#384457
   • https://github.com/lemonsqueeze/boot-chroot
2. Centos/RHEL 7 - Fix LVM boot issues after migration from ESXi to VirtualBox 2018-04-20

   tags: boot, bootloader/grub, filesystem, filesystem/lvm, fstab, linux, linux/centos, linux/kernel, linux/red-hat

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   Here are the steps I used to migrate a CentOS 7 VM from (presumably?) an ESXi server, to a local VirtualBox environment.

   The LVM volumes were not detected at boot, and after the boot timeout, the OS fell back to the Dracut emergency shell.

   • get a CentOS minimal installation CD
   • check the VM's resources and peripherals:
     • ensure there are no floppy drives (!)
     • setup CPU and RAM resources
     • check virtual drives
     • add an SCSI optical drive if needed
   • optional: convert the virtual drive images from VMDK to VDI
   • mount the CentOS installation disc
   • boot on the installation disc:
     • select "Troubleshooting", then "Rescue"
     • let the rescue utility detect filesystems and mountpoints
   • $ chroot to the detected environment
   • backup files:
     • /etc/fstab
     • /boot/grub/grub.cfg
   • under /boot, backup the initrd and initramfs for the current configuration (these will be overwritten)
   • compare the current /etc/fstab with the output of $ lsblk and $ blkid
   • if needed, manually edit /etc/fstab to use the appropriate block device UUIDs, identifiers and mountpoints
   • regenerate GRUB configuration:
     • $ grub2-mkconfig -o /boot/grub2/grub.cfg
   • if needed, reinstall GRUB:
     • $ grub-install /dev/sda
   • rebuild initrd:
     • $ mkinitrd --force /boot/<initrd_image> <kernel_version>
   • rebuild initramfs:
     • $ dracut --force <kernel_version>
   • exit the chroot
   • unmount the installation disc
   • reboot
   • optional but highly recommended: cross your fingers
   • ...
   • profit!
3. "Don't run this on any system you expect to be up" they said, but we did it anyway - Byte Blog 2017-07-20

   tags: chroot, hardware/ram, linux, linux/ubuntu, live, upgrade

   [ permalink ]

   • https://github.com/marcan/takeover.sh
   • https://news.ycombinator.com/item?id=13622301
   • https://linux.die.net/man/8/debootstrap
   • https://linux.die.net/man/8/pivot_root
   • https://linux.die.net/man/2/pivot_root
4. Chrooted SSH/SFTP Tutorial (Debian Lenny) 2016-01-06

   tags: chroot, ftp, linux/debian, network/ssh, network/ssh/sftp, sysadmin

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   http://www.fuschlberger.net/programs/ssh-scp-sftp-chroot-jail/ http://askubuntu.com/questions/420652/how-to-setup-a-restricted-sftp-server-on-ubuntu https://www.debian-administration.org/article/94/How_to_restrict_users_to_SFTP_only_instead_of_SSH