Building systemd
================

Install dependencies
--------------------
::

    apt build-dep systemd

Clone and compile systemd
-------------------------
::

    git clone https://github.com/systemd/systemd
    cd systemd
    ./autogen.sh
    ./configure CFLAGS='-g -O0 -ftrapv' --sysconfdir=/etc --localstatedir=/var --libdir=/usr/lib  --with-rootprefix=/ --with-rootlibdir=/lib
    make -j`nproc`

The generated binaries will be in .libs

Hacky way to test new systemd-networkd binary
---------------------------------------------

Check that the system binary is different to the generated binary::

    sha256sum .libs/systemd-networkd /lib/systemd/systemd-networkd

To find required library::

    ldd .libs/systemd-networkd | grep system

To find which declarations are missing::

    readelf -Ws /lib/systemd/libsystemd-shared-233.so | grep config_parse_uint
    readelf -Ws .libs/libsystemd-shared-233.so | grep config_parse_uint

Configure network::

    cat /etc/systemd/network/20-dhcp.network

    [Match]
    Name=en*

    [Network]
    DHCP=ipv4

    [DHCP]
    UseAnonymityProfile=true

Replace system binaries with the compiled ones:

If Network Manager is running, stop it::

    systemctl stop NetworkManager

Restart::

    systemctl restart systemd-networkd

To keep it running in the system::

    systemctl enable systemd-networkd
    systemctl enable systemd-resolved
    systemctl disable NetworkManager

To enable wifi interface::

    wpa_passphrase MyNetwork SuperSecretPassphrase > /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
    systemctl enable wpa_supplicant@wlan0.conf

To obtain debugging logs, add to the unit::

    [Service]
    Environment=SYSTEMD_LOG_LEVEL=debug

The unit in Debian is in ``/lib/systemd/system/systemd-networkd.service``

If other unit is created, it needs to have the correct file system permissions::

    touch /etc/systemd/system/name.service
    chmod 664 /etc/systemd/system/name.service


Scan DHCP packages
------------------
::

    /usr/sbin/tcpdump -r /tmp/dhcp-before.pcap -X -n

Tests
-----
::

    make -j`nproc` check