Quick tip - Troubleshooting networkd

To troubleshoot networkd in case of failure we can enable debug mode using the following procedure, this is applicable to Photon OS or any other linux system using networkd

First create /etc/systemd/system/systemd-networkd.service.d/ directory.

mkdir -p /etc/systemd/system/systemd-networkd.service.d/

In the previous path create the 10-debug.conf drop-in snippet with the following content.

[Service]
Environment=SYSTEMD_LOG_LEVEL=debug

Reload systemd and restart systemd-networkd.

systemctl daemon-reload
systemctl restart systemd-networkd

Using journalctl we can now see more detailed information in networkd log.

root@lightwave01 [ ~ ]# journalctl -u systemd-networkd -f
-- Logs begin at Sat 2016-02-06 20:42:47 UTC. --
Feb 07 03:01:07 lightwave01 systemd-networkd[428]: ICMPv6 CLIENT: Error sending Router Solicitation
Feb 07 03:01:10 lightwave01 systemd-networkd[428]: DHCP CLIENT (0xd25e35e9): DISCOVER
Feb 07 03:01:12 lightwave01 systemd-networkd[428]: ICMPv6 CLIENT: Error sending Router Solicitation
Feb 07 03:01:16 lightwave01 systemd-networkd[428]: DHCPv6 CLIENT: Next retransmission in 1.123266s
Feb 07 03:01:17 lightwave01 systemd-networkd[428]: DHCPv6 CLIENT: Next retransmission in 2.323319s
Feb 07 03:01:18 lightwave01 systemd-networkd[428]: DHCP CLIENT (0xd25e35e9): DISCOVER
Feb 07 03:01:19 lightwave01 systemd-networkd[428]: DHCPv6 CLIENT: Next retransmission in 4.642094s
Feb 07 03:01:24 lightwave01 systemd-networkd[428]: DHCPv6 CLIENT: Next retransmission in 9.555344s
Feb 07 03:01:33 lightwave01 systemd-networkd[428]: DHCP CLIENT (0xd25e35e9): DISCOVER
Feb 07 03:01:33 lightwave01 systemd-networkd[428]: DHCPv6 CLIENT: Next retransmission in 19.683553s

– Juanma