Ensure udp_pmtu_discover is disabled

MediumLevel 1Automatedaix

Description

The udp_pmtu_discover parameter controls whether MTU discovery is enabled. The udp_pmtu_discover parameter will be set to 0. The idea of MTU discovery is to avoid packet fragmentation between remote networks. Audit: `no -o udp_pmtu_discover` must report 0.

How it is checked

Audit method: Shell command

shell

command -v no >/dev/null 2>&1 || exit 1; out=$(no -o udp_pmtu_discover 2>/dev/null) || exit 1; printf '%s\n' "$out" | sed 's/[[:blank:]]*=[[:blank:]]*/=/'

Expected output: udp_pmtu_discover=0

How it is fixed

Fix method: Guidance or infrastructure patch

no -p -o udp_pmtu_discover=0 (sets the running value and makes it persistent in /etc/tunables/nextboot)

Properties

Operating systems: Any
Tags: aixhardening
Reference: CIS IBM AIX 7 Benchmark v1.2.0 - 4.5.18 Ensure udp_pmtu_discover is disabled

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target aix