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#!/bin/bash
# return the external interface
_get_external_interface() {
ip route get 1.1.1.1 | head -1 | cut -d' ' -f5
}
# permit tunnel on server
permit_tunnel() {
echo 'PermitTunnel=yes' >> /etc/ssh/sshd_config
service sshd reload
}
# enable ip_forward
kernel_forwarding() {
echo 1 > /proc/sys/net/ipv4/ip_forward
}
# firewall rules
firewall_rules() {
local device
for device in tun tap; do
iptables -I FORWARD -i $device+ -j ACCEPT
iptables -I FORWARD -o $device+ -j ACCEPT
iptables -I INPUT -i $device+ -j ACCEPT
done
local external_interface=`_get_external_interface`
iptables -t nat -I POSTROUTING -o $external_interface -j MASQUERADE
}
# main
main() {
permit_tunnel
kernel_forwarding
firewall_rules
}
main "$@"
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