Linux distributions
TMA-ROCKY8-3.3.1.18
Ensure net.ipv4.tcp_syncookies is configured
Опис
When tcp_syncookies is set, the kernel will handle TCP SYN packets normally until the half-open connection queue is full, at which time, the SYN cookie functionality kicks in. SYN cookies work by not using the SYN queue at all. Instead, the kernel simply replies to the SYN with a SYN/ACK, but will include a specially crafted TCP sequence number that encodes the source and destination IP address and port number and the time the packet was sent. A legitimate connection would send the ACK packet of the three way handshake with the specially crafted sequence number. This allows the system to verif
Како се проверава
Метод провере: Команда љуске
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 $f in configuration"; return 1;; esac; }; if chk net.ipv4.tcp_syncookies 1; then echo compliant; fi- Очекивани излаз
compliant
Како се исправља
Метод исправке: Смерница или закрпа инфраструктуре
1. Review all files being used by systemd sysctl and comment out or remove all net.ipv4.tcp_syncookies lines that are not net.ipv4.tcp_syncookies=1. Example script: #!/usr/bin/env bash { l_option="net.ipv4.tcp_syncookies" l_value="1" l_grep="${l_option//./(\\.|\\/)}" a_files=() l_systemdsysctl="$(readlink -e /lib/systemd/systemd-sysctl \ || readlink -e /usr/lib/systemd/systemd-sysctl)" l_ufw_file="$([ -f /etc/default/ufw ] && \ awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)" [ -f "$(readlink -e "$l_ufw_file")" ] && \ a_files+=("$l_ufw_file"); a_files+=("/etc/sysctl.conf") while IFS= read -r l_fname; do l_file="$(readlink -e "${l_fname//# /}")" [ -n "$l_file" ] && ! grep -Psiq -- '(…
Својства
- Оперативни системи
- rocky-8
- Ознаке
- cis-convertedkernellinuxsysctl
- Референца
- CIS Rocky Linux 8 Benchmark v3.0.0 - 3.3.1.18
Проверите овај рачунар
Покрените ово на рачунару за који имате дозволу за проверу. Скенирање ради у режиму само за читање.
tmaegis scan --target linux