==== IPv6 Tunnelbroker with systemd-networkd ====
<code>
# cat > /etc/systemd/network/he-tunnel.netdev << EOF
[Match]

[NetDev]
Name=he-ipv6
Kind=sit
MTUBytes=1480

[Tunnel]
Local=<your_ip_address>
Remote=<tunnelbroker_endpoint>
TTL=255
EOF

# cat > /etc/systemd/network/he-tunnel.network << EOF
[Match]
Name=he-ipv6

[Network]
Address=2001:470:<yourprefix>::2/64
Gateway=2001:470:<yourprefix>::1
EOF

# sed -i '/\[Network\]/aTunnel=he-ipv6' /etc/systemd/network/default.network
</code>

Add another Address= line for your routed /64.

==== Use BBR ====
<code>
echo -e "\nnet.core.default_qdisc=fq\nnet.ipv4.tcp_congestion_control=bbr" >> /etc/sysctl.conf
sysctl -p
</code>

To install latest kernel on Xenial: [[linux#install_zesty_kernel_49_on_xenial]]

==== More Tolerant ICMP Ratelimit ====
<code>
echo -e "\nnet.ipv4.icmp_ratelimit=50" >> /etc/sysctl.conf
sysctl -p
</code>

==== /dev/net/tun Not Found? ====
<code>
mkdir -p /dev/net
mknod /dev/net/tun c 10 200
</code>