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TMA-ALMA9-3.3.1.3

Ensure net.ipv4.conf.default.forwarding is configured

MittelStufe 1Automatisiertlinux

Beschreibung

ICMP Redirects are used to send routing information to other hosts. As a host itself does not act as a router (in a host only configuration), there is no need to send redirects. net.ipv4.conf.default.forwarding controls forwarding of IPv4 packet on newly added network interfaces. More information about the kernel parameter configuration files, their location, and load preference is available in the "Configure Network Kernel Parameters" section overview. Note: • If this system is a router this recommendation is not applicable. • If net.ipv4.ip_forward=0 is configured, this recommendation may be

So wird geprüft

Prüfmethode: Shell-Befehl

shell
chk() { p=$1; allowed=" $2 "; case $p in net.ipv6.*) [ -d /proc/sys/net/ipv6 ] || return 0;; esac; v=$(sysctl -n "$p" 2>/dev/null) || { echo "$p: not available"; return 1; }; case "$allowed" in *" $v "*) ;; *) echo "$p is $v (running)"; return 1;; esac; sd=$(readlink -e /lib/systemd/systemd-sysctl || readlink -e /usr/lib/systemd/systemd-sysctl); f=$("$sd" --cat-config 2>/dev/null | grep -Po "^\h*${p//./\.}\h*=\h*\K\H+" | tail -n1); [ -n "$f" ] || { echo "$p is not set in any sysctl configuration file"; return 1; }; case "$allowed" in *" $f "*) ;; *) echo "$p is $f in configuration"; return 1;; esac; }; if chk net.ipv4.conf.default.forwarding 0; then echo compliant; fi
Erwartete Ausgabe
compliant

So wird behoben

Behebungsmethode: Anleitung oder Infrastruktur-Patch

1. Review all files being used by systemd sysctl and comment out or remove all net.ipv4.conf.default.forwarding lines that are not net.ipv4.conf.default.forwarding=0. Example script: #!/usr/bin/env bash { l_option="net.ipv4.conf.default.forwarding" l_value="0" l_grep="${l_option//./(\\.|\\/)}" a_files=() l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \ || readlink -e /usr/lib/systemd/systemd-sysctl)" a_files+=("/etc/sysctl.conf") while IFS= read -r l_fname; do l_file="$(readlink -e "${l_fname//# /}")" [ -n "$l_file" ] && ! grep -Psiq -- '(^|\h+)'"$l_file"'\b' \ <<< "${a_files[*]}" && a_files+=("$l_file") done < <("$l_systemdsysctl" --cat-config | tac | \ grep -Psio -- '^\h*#\h*\/…

Eigenschaften

Betriebssysteme
almalinux-9
Tags
cis-convertedkernellinuxsysctl
Referenz
CIS AlmaLinux OS 9 Benchmark v3.0.0 - 3.3.1.3

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