====== IP configuration ======

===== Debian =====

<file bash /etc/network/interfaces>
# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet static
        address 192.168.21.2/24
        gateway 192.168.21.1
iface eth0 inet6 static
        address fd18:76a0:3427:201::2/64
iface eth0 inet6 auto
</file>

=== IPv6: token or DHCP ===

<file bash /etc/network/interfaces>
iface eth0 inet6 auto #SLAAC
    pre-up /sbin/ip token set ::48 dev eth0 #configure static token with changing prefix

iface eth1 inet6 dhcp #DHCPv6
</file>
((token setup from [[https://medium.com/@xchewtoyx/token-ipv6-post-8ad39d645636]]))

=== IPv6: EUI-64 ===

<file . /etc/sysctl.conf>
net.ipv6.conf.default.addr_gen_mode = 0
net.ipv6.conf.eth0.addr_gen_mode = 0
</file>

=== DHCPv4 DUID identifier ===

''ifupdown'' sends ''dhclient -i'' Flag (use DHCPv6 DUID for v4) by default now. To revert backt to MAC-Address set following item in ''dhclient.conf'':((https://superuser.com/a/1553114))

<file . /etc/dhcp/dhclient.conf>
send dhcp-client-identifier = hardware;
</file>

or this option in ''/etc/network/interface'':((https://superuser.com/a/1648918))

<file . /etc/network/interfaces>
iface eth0 inet dhcp
    client no
</file>

=== Disable v6 completely ===

<file . /etc/sysctl.conf>
net.ipv6.conf.eth0.disable_ipv6 = 1 #replace eth0 with desired interface or all
</file>

===== Ubuntu 18.04 =====

<file xml /etc/netplan/50-cloud-init.yaml>
# This file is generated from information provided by
# the datasource.  Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}


network:
    ethernets:
        eth0:
            dhcp4: no
            addresses:
            - 192.168.25.40/24
            - 2001:6b0:1234:1470::40/64
            gateway4: 192.168.25.1
            gateway6: 2001:6b0:1234:1470::1
    version: 2
</file>

<code bash>
sudo netplan apply
</code>

===== IPv6 Token =====

**not persistent**

<code bash>
sudo ip token set ::27 dev eth0
</code>

**persistent**

add token addr and fe80 with that number

<file . /etc/network/interfaces>
iface eth0 inet6 auto
        pre-up /sbin/ip token set ::40 dev eth0
        up /sbin/ip -6 addr add fe80::40/64 dev eth0
</file>


===== Mit ip addr =====

<code bash>
sudo ip addr add 2003:59:6034::26:4/64 dev eth1
sudo ip route add ::/0 via 2003:59:6034::1 dev eth1
</code>

===== Token in /etc/network/interfaces =====

https://gist.github.com/xchewtoyx/f90e4696e9726711673b81d8aff8acff#file-gistfile1-txt