TMA-COS-3.2.6

Ensure bogus ICMP responses are ignored

보통레벨 1자동cos

설명

Setting icmp_ignore_bogus_error_responses to 1 prevents the kernel from logging bogus responses (RFC-1122 non-compliant) from broadcast reframes, keeping file systems from filling up with useless log messages. Some routers (and some attackers) will send responses that violate RFC-1122 and attempt to fill up a log file system with many useless error messages.

점검 방법

감사 방식: 셸 명령

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.icmp_ignore_bogus_error_responses 1; then echo compliant; fi

예상 출력: compliant

조치 방법

조치 방식: 가이드 또는 인프라 패치

Set the following parameter in /etc/sysctl.conf or a /etc/sysctl.d/* file: net.ipv4.icmp_ignore_bogus_error_responses = 1 Run the following commands to set the active kernel parameters: # sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1 # sysctl -w net.ipv4.route.flush=1 /etc is stateless on Container-Optimized OS. Therefore, /etc cannot be used to make these changes persistent across reboots. The steps mentioned above needs to be performed after every boot.

속성

운영 체제: 모두
태그: container-optimized-oscos
참고 자료: CIS Google Container-Optimized OS Benchmark v1.2.0 - 3.2.6 Ensure bogus ICMP responses are ignored

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shell

tmaegis scan --target cos