If the Trivial File Transfer Protocol (TFTP) server is required, RHEL 9 TFTP daemon must be configured to operate in secure mode.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-257952	RHEL-09-252055	SV-257952r925843_rule		Medium

Description
Restricting TFTP to a specific directory prevents remote users from copying, transferring, or overwriting system files. Using the "-s" option causes the TFTP service to only serve files from the given directory.

STIG	Date
Red Hat Enterprise Linux 9 Security Technical Implementation Guide	2023-12-01

Details

Check Text ( C-61693r925841_chk )

Verify the TFTP daemon is configured to operate in secure mode. Check if a TFTP server is installed with the following command: $ sudo dnf list --installed tftp-server Example output: tftp-server.x86_64 5.2-35.el9.x86_64 Note: If a TFTP server is not installed, this requirement is Not Applicable. If a TFTP server is installed, check for the server arguments with the following command: $ systemctl cat tftp | grep ExecStart ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot If the "ExecStart" line does not have a "-s" option, and a subdirectory is not assigned, this is a finding.

Fix Text (F-61617r925842_fix)
Configure the TFTP daemon to operate in secure mode. 1. Find the path for the systemd service. $ sudo systemctl show tftp | grep FragmentPath= FragmentPath=/etc/systemd/system/tftp.service 2. Edit the ExecStart line on that file to add the -s option with a subdirectory. ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot