macos

macOS TFTP server

Posted on by Jesper Ramsgaard

I have never really found a good TFTP for macOS. Is it funny that macOS is much used by network people but there isn’t a decent TFTP server?

Well, there is. macOS has it built-in, no GUI though. But that’s also fine, as long as you know to use it. It’s disabled by default, but you can start and stop it with the following commands.

The TFTP daemon uses the /private/tftpboot folder so we are going to copy the file there. Then set the correct permissions on the file.

There is a gotcha with the TFTP daemon, which is you cant copy a file to the TFTP daemon if that file does not already exist there.  To work around it you can just create a file and set the permission for it. Then your devices will just send data into the pre-created file.

Using dd – disk cloning

Posted on by Jesper Ramsgaard

dd (disk duplication) is a utility that can read raw data of a disk, even if the Mac doesn’t understand the filesystem.

I have used it before in p2v a physical to a virtual server. For details take a look at this article.

  • if= specifies input path (file, or device)
  • of= specifies output path (file, or device)
  • bs=n sets both input and output block size (optional, default=512 byte blocks)
  • conv=noerror,sync tells dd to be fault-tolerant and ignore read errors (optional)

If the operation stops with an I/O error, trying to salvage all readable data with conv=noerror,sync.
This option can often recover a dead hard drive or an unreadable file, but it does not repair the error.

Make a clone of a disk:

In this case, I was fooling around with a Microsoft StorSimple appliance and wanted to have a backup of it to go back to if I messed it up too badly. This is not the first time I have done it, and sure not the last time, and always forgot the commands, so to future Jesper, here goes.

Open Terminal and try this:

  1. Attach and identify the source disk:

2. if mounted, unmount the source disk:

Copy the source disk to the desktop:

If you want to save space, make it gzip it with:

Failed disk backup:

If the copy fails due to disk errors, try using the following command at step 3:

dd will take much longer using this option, errors are written as null bytes. fsck / chkdsk the disk afterward.

Notes:

  • Using /dev/rdisk# (raw disk) in place of /dev/disk# is much faster
  • You can check progress, while the command is running, by pressing Ctrl-T
  • If you can attach both disks, copy directly: sudo dd if=/dev/disk2 of=/dev/disk3 bs=64k