• Part 1 – running tftp server non root (xinetd)
• Part 2 – the tftp client requires firewalld changes as well
• Part 3 – replacing xinetd with systemd (this blog post)

Oooh, nice one systemd.

During my investigation in Part 1, I tried to eliminate xinetd as the reason for the misbehaviour.

I started up the tftp socket:

● tftp.socket - Tftp Server Activation Socket
   Loaded: loaded (/usr/lib/systemd/system/tftp.socket; disabled; vendor preset: disabled)
   Active: active (listening) since Tue 2019-03-12 17:03:11 UTC; 3h 16min ago
   Listen: [::]:69 (Datagram)

And the really cool thing about that is that it works just like xinetd. tftpd.service is still disabled, but this acts as a listener, and starts that service when a connection arrives.

No need to install something else.

You then have to supply modifications to the tftpd.service definition to change its parameters.

• I’ve blogged about doing that.
• It does NOT use the xinetd configuration file (which tftp-server package still installs.)

tftp.socket

Don’t forget to get rid of xinetd if you don’t need it;  otherwise it may still be listening on port 69, and systemd won’t be doing much. If you do need xinetd, set ‘disable’ to yes in /etc/xinetd.d/tftp.

# yum erase xinetd
# systemctl enable tftp.socket
# systemctl start tftp.socket
# systemctl status tftp.socket
● tftp.socket - Tftp Server Activation Socket
   Loaded: loaded (/usr/lib/systemd/system/tftp.socket; enabled; vendor preset: disabled)
   Active: active (listening) since Wed 2019-05-01 16:10:34 UTC; 32min ago
   Listen: [::]:69 (Datagram)

tftp.service

Via a drop-in file, I’ve reconfigured it to

• serve up a different location
• log more verbosely
• keep running for five minutes
• use a specific account (not ‘nobody’) to do the actual tftping.

# systemctl cat tftp.service
# /usr/lib/systemd/system/tftp.service
[Unit]
Description=Tftp Server
Requires=tftp.socket
Documentation=man:in.tftpd

[Service]
ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot
StandardInput=socket

[Install]
Also=tftp.socket

# /etc/systemd/system/tftp.service.d/params.conf
# managed by puppet profile::build::tftp
[Service]
ExecStart=
ExecStart=/usr/sbin/in.tftpd -s /srv/tftp/pxe -vv -u tftp --ipv4 --timeout 300

Normally, it’s inactive and disabled:

● tftp.service - Tftp Server
   Loaded: loaded (/usr/lib/systemd/system/tftp.service; indirect; vendor preset: disabled)
  Drop-In: /etc/systemd/system/tftp.service.d
           └─params.conf
   Active: inactive (dead)
     Docs: man:in.tftpd

Trigger it ..

$ tftp -4 -v 192.168.1.221 -c get pxelinux.cfg/dhcpbasic_template
Connected to 192.168.1.221 (192.168.1.221), port 69
getting from 192.168.1.221:pxelinux.cfg/dhcpbasic_template to dhcpbasic_template [netascii]
Received 293 bytes in 0.1 seconds [17818 bit/s]

then

# systemctl status tftp.service
● tftp.service - Tftp Server
   Loaded: loaded (/usr/lib/systemd/system/tftp.service; indirect; vendor preset: disabled)
  Drop-In: /etc/systemd/system/tftp.service.d
           └─params.conf
   Active: active (running) since Wed 2019-05-01 16:42:55 UTC; 8s ago
     Docs: man:in.tftpd
 Main PID: 5887 (in.tftpd)
   CGroup: /system.slice/tftp.service
           └─5887 /usr/sbin/in.tftpd -s /srv/tftp/pxe -vv -u tftp --ipv4 --timeout 300
May 01 16:42:55 systemd[1]: Started Tftp Server.

Log entries for actual TFTP traffic still only appear in /var/log/messages; journald doesn’t pick them up, so you can’t get the traffic logging this way:

# journalctl --unit=tftp.service