OSX SL tftp doesn’t work?

…then this may be the reason… took me hours to figure out. Had to get it going for a netboot project, and the netboot just kept circling around the boot image download without getting much anywhere. First, check out Bombich’s troubleshooting, which put me on the right track without actually giving me the solution, but maybe that’s because my particular problem is relatively new. It may have been introduced with Snow Leopard.

What happened in my case is that I was able to download an image using the form:

tftp myserver.local
get NetBoot/NetBootSP0/Netinstall.nbi/i386/booter

…but not using the form:

tftp 172.25.26.27
get NetBoot/NetBootSP0/Netinstall.nbi/i386/booter

even though the “myserver.local” name pointed to the IP 172.25.26.27. At least, that’s what I presumed until I whipped out Wireshark and found out that using the “myserver.local” name resolved to an IPv6 address, not the IPv4 address I expected.

Next, I ran this on the server:

sudo lsof -i :69

COMMAND PID USER   FD   TYPE     DEVICE SIZE/OFF NODE NAME
launchd   1 root  144u  IPv6 0x0a9ab4a0      0t0  UDP *:tftp

Aha! The tftp server only runs IPv6 for some reason. That explains it.

To fix this, go into the tftp.plist file with pico:

sudo pico /System/Library/LaunchDeamons/tftp.plist

and add the optional key for IPv4 a bit down:

...
<key>Sockets</key>
<dict>
    <key>Listeners</key>
    <dict>
        <key>SockServiceName</key>
        <string>tftp</string>
        <key>SockType</key>
        <string>dgram</string>
        <key>SockFamily</key>
        <string>IPv4</string>
    </dict>
</dict>
...

After that, all you need to do is stop and restart tftp:

sudo launchctl unload /System/Library/LaunchDaemons/tftp.plist
sudo launchctl load -w /System/Library/LaunchDaemons/tftp.plist

Then check that the port is working on IPv4 as well:

COMMAND PID USER   FD   TYPE     DEVICE SIZE/OFF NODE NAME
launchd   1 root  144u  IPv6 0x0a9ab4a0      0t0  UDP *:tftp
launchd   1 root  150u  IPv4 0x07e2ee14      0t0  UDP *:tftp

After that, retry the tftp get command using both IPv4 and “myserver.local” addressing. Should work now. I must admit I don’t understand why IPv6 keeps working, though. Oh well, not that it bothers me, but it bothers me a little bit.

Update: this post is correct, but it still didn’t solve my problem, so please see next blog post for more, at least if you’re doing netboot stuff on Snow Leopard