Come si fa TFTP su un Mac?



di

Eseguire un server TFTP per configurazioni di dispositivi di rete

...su Mac OS X o macOS

Di Rick Cogley

6-feb-2017
Software Tips Sysadmin

TOC

  • PreparazioneTrova i comandi appropriatiAvvia tftpdServe un file firmwareSymlink alla cartella tftpbootCopia il file del firmware in posizioneOttieni il file del firmware da tftpdPorta un file da un dispositivo a tftpdStop tftpdAlternative

Se stai lavorando con dispositivi di rete come switch, router o firewall, per aggiornare il loro firmware, spesso si ha bisogno di un server TFTP. Ecco come usare quello incluso in Mac OS X o macOS.

Preparazione

Mac OS X ha un server tftp incluso, e devi solo avviarlo e fare un po' di configurazione.

L'ho trovato e impostato in questo modo:

Trova i comandi appropriati

Usa il comando apropos per vedere se ci sono comandi relativi a tftp. From Terminal:

Bash

  1. apropos tftp 

The command replies:

Bash

  1. tftp(1) - trivial file transfer program 
  2. tftpd(8) - DARPA Internet Trivial File Transfer Protocol server 

Since the commands exist, you can use man to get more info. We would want the server version of this command, so that is the one with the d suffix (d is for “daemon”).

Bash

  1. man tftpd 

Looking at these results and Apple’s online version of the man info, we see it says:

This server should not be started manually; instead, it should be run using launchd(8) using the plist /System/Library/LaunchDaemons/tftp.plist. It may be started using the launchctl(1) load command; refer to the documentation for that utility for more information.

Start tftpd

The man file gives you the plist to use, so, you just start it with launchctl:

Bash

  1. sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist 

… and tftpd will start. Supply your password when sudo prompts for it.

You can confirm it’s running using netstat to check what is listening on its port, traditionally port 69.

Bash

  1. netstat -na |grep *.69 

It will show:

Bash

  1. udp6 0 0 *.69 *.* 
  2. udp4 0 0 *.69 *.* 

Serve a Firmware File

Now that the tftpd server is started, you need to put the firmware binary file in a specific location for the tftpd to be able to serve it to a requesting device. Namely your firmware files should be saved to /private/tftpboot. The tftp.plist file looks like this:

Xml

  1. <?xml version="1.0" encoding="UTF-8"?> 
  2. .0"> 
  3.  
  4. Disabled 
  5.  
  6. Label 
  7. com.apple.tftpd 
  8. ProgramArguments 
  9.  
  10. /usr/libexec/tftpd 
  11. -i 
  12. /private/tftpboot 
  13.  
  14. inetdCompatibility 
  15.  
  16. Wait 
  17.  
  18.  
  19. InitGroups 
  20.  
  21. Sockets 
  22.  
  23. Listeners 
  24.  
  25. SockServiceName 
  26. tftp 
  27. SockType 
  28. dgram 
  29.  
  30.  
  31.  
  32.  

Symlink the tftpboot folder

You used to be able to change the tftpboot path, but OS X El Capitan and later macOSs have stronger security via their “SIP” system which makes things more difficult. Just symlink the tftpboot to a folder you have full control over. You can do it like this:

Bash

  1. cd /private/ 
  2. sudo rm -rf tftpboot 
  3. mkdir /Users/myuser/tftpboot 
  4. sudo ln -s /Users/myuser/tftpboot tftpboot 
  5. sudo launchctl unload -F /System/Library/LaunchDaemons/tftp.plist 
  6. sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist 

That being said, please note that I tested a fresh macOS Sierra install directly on /private/tftpboot, and tftp get and put from another Mac worked fine without the symlink in place, so YMMV. I confirmed with csrutil status that SIP is indeed enabled on my fresh macOS.

Japanese Mac keyboards don’t handle reverse solidus . To enter one you can press option-¥.

Copy firmware file into position

Now let’s serve a file. Let’s say we download a firmware for an HP switch, and want to upgrade its firmware to that version. The file downloaded is F_05_80.swi and is saved to our Downloads folder. Let’s move it to the correct folder, and set its permissions.

Bash

  1. cd /Users/myuser/tftpboot 
  2. cp ~/Downloads/hp/F_05_80.swi . 
  3. ls 
  4. chmod 766 F_05_80.swi 

Get firmware file from tftpd

Screenshot: HP Switch Firmware Upgrade UI

It differs by each device you’re upgrading, but typically you would set these:

  • Method of upgrade: select tftp usually.
  • IP address of tftpd server. This is the IP of your mac.
  • Name of firmware file. Enter the exact name, getting the case exactly right.

Then there is usually a way to “execute” the transfer by a command or menu. Una volta che il firmware è trasferito e caricato, il dispositivo di solito si riavvia.

Clicca lo screenshot per vedere come appare su uno switch HP.

Mettere un file da un dispositivo a tftpd

A volte vuoi salvare un file dal dispositivo, al tuo server tftp. Il protocollo tftp è stupido e non richiede autenticazione, quindi è necessario specificare in anticipo quale sarà il nome del file ricevuto. Use touchto do that.

Be sure to get the name exactly right, as mis-spellings are a common cause of errors here.

Bash

  1. touch ~/tftpboot/catalyst.conf 
  2. chmod 766 ~/tftpboot/catalyst.conf 

Now you have a blank file that will be overwritten, when you specify it from your remote device. Make sure you specify exactly the same filename.

Stop tftpd

Be sure to unload the service when you’re not using it:

Bash

  1. sudo launchctl unload -F /System/Library/LaunchDaemons/tftp.plist 
  2. netstat -na |grep *.69 

The aforementioned netstat command should return nothing.

Alternatives

There are a couple of GUI alternatives you can try, though I have not done so myself:

  • PumpKIN
  • TFTP Server

I hope this information helps someone.

Cheers!!