Ensure source routed packets are not accepted

MediaNivel 1Automatizadalinux

Descripción

In networking, source routing allows a sender to partially or fully specify the route packets take through a network. In contrast, non-source routed packets travel a path determined by routers in the network. In some cases, systems may not be routable or reachable from some locations (e.g. private addresses vs. Internet routable), and so source routed packets would need to be used.

Cómo se verifica

Método de auditoría: Comando de shell

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.accept_source_route 0 && chk net.ipv4.conf.default.accept_source_route 0 && chk net.ipv6.conf.all.accept_source_route 0 && chk net.ipv6.conf.default.accept_source_route 0; then echo compliant; fi

Salida esperada: compliant

Cómo se corrige

Método de corrección: Guía o parche de infraestructura

Set the following parameters in /etc/sysctl.conf or a /etc/sysctl.d/* file: net.ipv4.conf.all.accept_source_route = 0 net.ipv4.conf.default.accept_source_route = 0 net.ipv6.conf.all.accept_source_route = 0 net.ipv6.conf.default.accept_source_route = 0 Run the following commands to set the active kernel parameters: # sysctl -w net.ipv4.conf.all.accept_source_route=0 # sysctl -w net.ipv4.conf.default.accept_source_route=0 # sysctl -w net.ipv6.conf.all.accept_source_route=0 # sysctl -w net.ipv6.conf.default.accept_source_route=0 # sysctl -w net.ipv4.route.flush=1 # sysctl -w net.ipv6.route.flush=1

Propiedades

Sistemas operativos: alinux-2
Etiquetas: cis-convertedkernellinuxsysctl
Referencia: CIS Aliyun Linux 2 Benchmark v1.0.0 ARCHIVE - 3.2.1

Verificar este host

Ejecute esto en un equipo que tenga permiso para auditar. El escaneo es de solo lectura.

shell

tmaegis scan --target linux