tftp-hpa doesn't accept IPv4 connections by default

[Nick B.]

After upgrading to 15.04 on my server it seems tftp-hpa is not listening and/or accepting IPv4 connections. When an IPv4 client tries to connect this shows up in syslog

in.tftpd[4295]: connect: Address family not supported by protocol

netstat shows it's only listening on IPv6
sudo netstat -lp | grep tftp
udp6 0 0 [::]:tftp [::]:* 14327/in.tftpd

If I change the TFTP_ADDRESS option in /etc/default/tftp-hpa from "[::]:69" to "0.0.0.0:69" it works. But this breaks IPv6

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: tftp-hpa (not installed)
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
Date: Sat Apr 25 12:32:30 2015
Dependencies:
 gcc-4.9-base 4.9.1-16ubuntu6
 libc6 2.19-10ubuntu2.3
 libgcc1 1:4.9.1-16ubuntu6
 multiarch-support 2.19-10ubuntu2.3
InstallationDate: Installed on 2015-02-12 (72 days ago)
InstallationMedia: Ubuntu-Server 14.10 "Utopic Unicorn" - Release amd64 (20141022.2)
ProcEnviron:
 LC_CTYPE=en_US.UTF-8
 TERM=screen-bce
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/zsh
SourcePackage: tftp-hpa
UpgradeStatus: Upgraded to vivid on 2015-04-24 (1 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nine (nine-lesi)]

At me works at first client get, after that only if restart server.

I have ubuntu 15.04 upgraded from 14.10, and I have tried a apt-get remove --purge and install again, and continues.

[Justin Slay (justin-slay)]

I have the same issue where the first GET request works, but then times out and produces this error until service is restarted.

[Frans Oilinki (moilinki)]

It seems tftpd-hpa interprets option --address ::69 to mean that only listen on IPv6:
1. By default (with TFTP_ADDRESS="[::]:69") it is started as

    /usr/sbin/in.tftpd --listen --user tftp --address [::]:69 --secure --create /srv/tftp

2. netstat (command "sudo netstat -anutp | grep '[:]69'") shows:

        udp6 0 0 :::69 :::* 10681/in.tftpd

I do not know and I am not interested to check the source code if there is way to explicitly tell tftpd-hpa to listen on all interfaces, both IPv4 and IPv6, but if you just omit the --address option, tftpd-hpa - per netstat output - listens on all interfaces both IPv4 and IPv6; when I start tftp-hpa as "/usr/sbin/in.tftpd --listen --user tftp --secure --create /srv/tftp" then netstat shows

       udp 0 0 0.0.0.0:69 0.0.0.0:* 24607/in.tftpd
       udp6 0 0 :::69 :::* 24607/in.tftpd

I accomplished this by hacking /etc/init.d/tftpd-hpa as follows:

diff --git a/init.d/tftpd-hpa b/init.d/tftpd-hpa
index 115ca4e..a4a5b60 100755
--- a/init.d/tftpd-hpa
+++ b/init.d/tftpd-hpa
@@ -52,9 +52,15 @@ do_start()
                fi
        done

+ if [ "$TFTP_ADDRESS" = "[::]:69" ]; then # all interfaces
+ start-stop-daemon --start --quiet --oknodo --exec $DAEMON -- \
+ --listen --user $TFTP_USERNAME \
+ $TFTP_OPTIONS $TFTP_DIRECTORY
+ else
                start-stop-daemon --start --quiet --oknodo --exec $DAEMON -- \
                        --listen --user $TFTP_USERNAME --address $TFTP_ADDRESS \
                        $TFTP_OPTIONS $TFTP_DIRECTORY
+ fi
 }

 do_stop ()

[Frans Oilinki (moilinki)]

NOTE: There is an obvious limitation in the above "solution" - if you want to listen on different port then you are back to square one. I wish this helps someone to bypass the problem while waiting for proper and complete fix.

[Rafael Bijos Faidiga (1-ubuntuone)]

FIX:
Just edit /etc/default/tftpd-hpa and remove [::] from line TFTP_ADDRESS="[::]:69"

[Nick B. (futurepilot)]

That seems to work to get it to listen of both IPv4 and IPv6. Not sure if it's a true fix or just a workaround though. Did something in the code change?

% sudo netstat -lp | grep tftp
udp 0 0 *:tftp *:* 2095/in.tftpd
udp6 0 0 [::]:tftp [::]:* 2095/in.tftpd

[Nikolai Kristiansen (nikolaik)]

Can confirm that Rafael's change in comment #7 works :-)

[Robie Basak (racb)]

17:16 <rbasak> stgraber: any opinion on bug 1448500 please?

17:18 <stgraber> rbasak: if just :69 instead of [::]:69 causes it to do the right thing, I don't have a problem with that change

[Joshua Powers (powersj)]

The original issue was the following message "in.tftpd[4295]: connect: Address family not supported by protocol". This appears to have been fixed in version 5.2+20150808-1, see Debian bug 793921 (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=793921). This version is found in Xenial (16.04) or later.

Due to the fact that this bug was original found with Vivid (15.04) I would ask that it be verified on the supported version found in Xenial and reply if it still occurs. I will move the bug to incomplete until I hear back.

The second issue that was brought up in the bug discussion above was due to a change to default configuration. Namely /etc/default/tftpd-hpa was changed to use 'TFTP_ADDRESS="[::]:69"' due to LP: #1228340, which was over 3 years ago. This changed the default behavior in Trusty (14.04) and forward.

While I too do not see any IPv4 udp results while running `sudo netstat -lp | grep tftp`, I can confirm that connecting to a server setup with the default configuration using `tftp -4 <address>` works. I am not sure of the explanation yet, but if this is another issue we should file a different bug and track it. I however, do not believe that tftpd-hpa has been broken for 3 years.

This does not appear to affect Debian stable or unstable as the default configuration file in /etc/default/tftpd-hpa for both looks like:

TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/srv/tftp"
TFTP_ADDRESS="0.0.0.0:69"
TFTP_OPTIONS="--secure"

[Nick B. (futurepilot)]

I can confirm that it works with IPv4 as expected with the default configuration.

[Joshua Powers (powersj)]

Thanks for confirming! For the original issue of "Address family not supported by protocol" I am marking this as 'Fix Released'.

For the separate issue brought up about not seeing netstat output for IPv4, the following was brought to my attention: '...a process that binds on both by not specifying (or whatever it is it does) ends up in an "netstat --inet6 -nlp" listing but not that "netstat --inet -nlp" one.' As such I do not believe there is an issue here, understandably a user experience one with netstat, but not with tftp-hpa.