Ensure Reverse Path Filtering is enabled

OrtaDüzey 1Otomatiklinux

Açıklama

Setting net.ipv4.conf.all.rp_filterand net.ipv4.conf.default.rp_filter to 1 forces the Linux kernel to utilize reverse path filtering on a received packet to determine if the packet was valid. Essentially, with reverse path filtering, if the return packet does not go out the same interface that the corresponding source packet came from, the packet is dropped (and logged if log_martians is set).

Nasıl denetlenir

Denetim yöntemi: Kabuk komutu

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.all.rp_filter 1 && chk net.ipv4.conf.default.rp_filter 1; then echo compliant; fi

Beklenen çıktı: compliant

Nasıl düzeltilir

Düzeltme yöntemi: Kılavuz veya altyapı yaması

Set the following parameters in /etc/sysctl.conf or a /etc/sysctl.d/* file: net.ipv4.conf.all.rp_filter = 1 net.ipv4.conf.default.rp_filter = 1 Run the following commands to set the active kernel parameters: # sysctl -w net.ipv4.conf.all.rp_filter=1 # sysctl -w net.ipv4.conf.default.rp_filter=1 # sysctl -w net.ipv4.route.flush=1

Özellikler

İşletim sistemleri: alinux-2
Etiketler: cis-convertedkernellinuxsysctl
Referans: CIS Aliyun Linux 2 Benchmark v1.0.0 ARCHIVE - 3.2.7

Bu ana makineyi denetle

Bunu denetleme izniniz olan bir makinede çalıştırın. Tarama salt okunurdur.

shell

tmaegis scan --target linux