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@firogh
Forked from dpino/ns-inet.sh
Created Jun 6, 2020
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Setup a network namespace with Internet access
#!/usr/bin/env bash
# set -x
# Returns all available interfaces, except "lo" and "veth*".
available_interfaces()
{
local ifaces=(`ip li sh | cut -d " " -f 2`)
local ret=()
for each in ${ifaces[@]}; do
each=${each::-1}
if [[ ${each} != "lo" && ${each} != veth* ]]; then
ret+=( "$each" )
fi
done
echo ${ret[@]}
}
IFACE="$1"
if [[ -z "$IFACE" ]]; then
ifaces=$(available_interfaces)
if [[ ${#ifaces[@]} -gt 0 ]]; then
IFACE=${ifaces[0]}
echo "Using interface $IFACE"
else
echo "Usage: ./ns-inet <IFACE>"
exit 1
fi
fi
NS="ns1"
VETH="veth1"
VPEER="vpeer1"
VETH_ADDR="10.200.1.1"
VPEER_ADDR="10.200.1.2"
if [[ $EUID -ne 0 ]]; then
echo "You must be root to run this script"
exit 1
fi
trap cleanup EXIT
cleanup()
{
ip li delete ${VETH} 2>/dev/null
}
# Remove namespace if it exists.
ip netns del $NS &>/dev/null
# Create namespace
ip netns add $NS
# Create veth link.
ip link add ${VETH} type veth peer name ${VPEER}
# Add peer-1 to NS.
ip link set ${VPEER} netns $NS
# Setup IP address of ${VETH}.
ip addr add ${VETH_ADDR}/24 dev ${VETH}
ip link set ${VETH} up
# Setup IP ${VPEER}.
ip netns exec $NS ip addr add ${VPEER_ADDR}/24 dev ${VPEER}
ip netns exec $NS ip link set ${VPEER} up
ip netns exec $NS ip link set lo up
ip netns exec $NS ip route add default via ${VETH_ADDR}
# Enable IP-forwarding.
echo 1 > /proc/sys/net/ipv4/ip_forward
# Flush forward rules.
iptables -P FORWARD DROP
iptables -F FORWARD
# Flush nat rules.
iptables -t nat -F
# Enable masquerading of 10.200.1.0.
iptables -t nat -A POSTROUTING -s ${VPEER_ADDR}/24 -o ${IFACE} -j MASQUERADE
iptables -A FORWARD -i ${IFACE} -o ${VETH} -j ACCEPT
iptables -A FORWARD -o ${IFACE} -i ${VETH} -j ACCEPT
# Get into namespace
ip netns exec ${NS} /bin/bash --rcfile <(echo "PS1=\"${NS}> \"")
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