Create services for TCP6 to TCP4 forwards with socat

create_socat_forward_service.sh

#!/usr/bin/env bash
# Forward list of ports from TCP6 to TCP4

if ! [ -x "$(command -v socat)" ]; then
  echo 'Error: socat is not installed.' >&2
  exit 1
fi

ports=(80 443)

for port in "${ports[@]}"
do

cat <<EOF > /usr/local/socat-ipv6-tcp-${port}-forward.sh
#!/bin/bash
# 6to4 forward
/usr/bin/socat TCP6-LISTEN:${port},fork TCP4:127.0.0.1:${port}
EOF

chmod +x /usr/local/socat-ipv6-tcp-${port}-forward.sh

cat <<EOF > /etc/systemd/system/socat-ipv6-tcp-${port}-forward.service
[Unit]
Description=socat forward TCP6 port ${port} to TCP4
After=network.target

[Service]
Type=simple
User=root
ExecStart=/usr/local/socat-ipv6-tcp-${port}-forward.sh
Restart=on-abort

[Install]
WantedBy=multi-user.target
EOF

systemctl daemon-reload;
systemctl enable socat-ipv6-tcp-${port}-forward.service;
systemctl start socat-ipv6-tcp-${port}-forward.service;
systemctl status socat-ipv6-tcp-${port}-forward.service;
done