How to troubleshoot TFTP Error code 2 on RHEL

by Danila Vershinin, September 10, 2021

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Operating System and Software

Rocky Linux 8

Problem

On a default installation of TFTP server, using get to retrieve files fails with Error code 2: xxxx
Attempt to retrieve a file using the relative path fails with Error code 2: Only absolute filenames allowed.

# tftp localhost
tftp> get testfile
Error code 2: Only absolute filenames allowed

Attempt to retrieve a file using the absolute path fails with Error code 2: Forbidden directory.

tftp> get /var/lib/tftpboot/testfile
Error code 2: Forbidden directory

How to Fix

The default installation of tftp-server on Rocky Linux 8 uses systemd instead of xinetd and does not require a config file to run.
Inspect any existing config files in /etc/xinetd.d.
In this instance, a config file for ftpd was present in /etc/xinetd.d/ftpd. This interfered with tftpd and resulted in the errors displayed.
Removing the ftpd config file then restarting xinetd resolved the issue.

Origin of the Problem

An existing config file for ftpd was present in /etc/xinetd.d/ftpd.

Diagnostic Steps

Install tftp-server and tftp packages on Rocky Linux 8.

# dnf install tftp-server tftp

Start tftp server.

# systemctl start tftp

# systemctl status tftp
 tftp.service - Tftp Server
   Loaded: loaded (/usr/lib/systemd/system/tftp.service; indirect; vendor preset: disabled)
   Active: active (running) since Thu 2020-07-09 10:46:07 BST; 5min ago
     Docs: man:in.tftpd
 Main PID: 27056 (in.tftpd)
    Tasks: 1 (limit: 11482)
   Memory: 376.0K
   CGroup: /system.slice/tftp.service
           └─27056 /usr/sbin/in.tftpd -s /var/lib/tftpboot

Jul 09 10:46:07 hostname.example.net systemd[1]: Started Tftp Server.

Create test file in the default directory /var/lib/tftpboot

# touch /var/lib/tftpboot/testfile

Check UDP port for tftpd is listening. This issue will only reproduce if the first entry displays the name of the service in.tftpd and xinetd

# ss -pluton | grep ":69"
udp    UNCONN   0        0                 0.0.0.0:69             0.0.0.0:*      users:(("in.tftpd",pid=10350,fd=0),("xinetd",pid=998,fd=6))
udp    UNCONN   0        0                       *:69                   *:*      users:(("systemd",pid=1,fd=220))

Attempt to retrieve a file using the relative path fails with Error code 2: Only absolute filenames allowed.

# tftp localhost
tftp> get testfile
Error code 2: Only absolute filenames allowed

Attempt to retrieve a file using the absolute path fails with Error code 2: Forbidden directory.

tftp> get /var/lib/tftpboot/testfile
Error code 2: Forbidden directory

Solutions