Ensure net.ipv4.ip_forward is configured

中レベル 1自動linux

説明

The net.ipv4.ip_forward flag tells the system whether it can forward IPv4 packets or not. 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.conf.all.forwarding=0 and net.ipv4.conf.default.forwarding=0 are configured, this recommendation may be skipped.

チェック方法

監査方法: シェルコマンド

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.ip_forward 0; then echo compliant; fi

期待される出力: compliant

修正方法

修正方法: ガイダンスまたは IaC パッチ

1. Review all files being used by systemd-sysctl and comment out or remove all net.ipv4.ip_forward lines that are not net.ipv4.ip_forward=0. Example script: #!/usr/bin/env bash { l_option="net.ipv4.ip_forward" 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 < <("$l_systemdsysctl" --cat-config | tac | \ grep -Psio -- '^\h*#\h*\/[^#\n\r\h]+\.conf\b') for l_file in "${…

プロパティ

オペレーティングシステム: rocky-9
タグ: cis-convertedkernellinuxsysctl
参照: CIS Rocky Linux 9 Benchmark v3.0.0 - 3.3.1.1

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監査が許可されているマシンで実行してください。スキャンは読み取り専用です。

shell

tmaegis scan --target linux