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Forked from dpino/ns-inet.sh
Created January 20, 2017 03:47
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Setup a network namespace with Internet access
#!/usr/bin/env bash
set -x
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
# 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 eth0 -j MASQUERADE
iptables -A FORWARD -i eth0 -o ${VETH} -j ACCEPT
iptables -A FORWARD -o eth0 -i ${VETH} -j ACCEPT
# Get into namespace
ip netns exec ${NS} /bin/bash --rcfile <(echo "PS1=\"${NS}> \"")
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