A daemon configures network and executes scripts on network events such as systemd-networkd's DBus events,
dhclient gains lease lease. It also watches when
- An address getting added/removed/modified.
- Links added/removed.
network-event-broker creates
- link state directories
carrier.d,configured.d,degraded.dno-carrier.droutable.d - manager state dir
manager.d routes.d(when routes gets modfied)
in /etc/network-event-broker. Executable scripts can be placed into directories.
Use cases:
How to run a command when get a new address is acquired via DHCP ?
systemd-networkd'sScripts are executed when the daemon receives the relevant event fromsystemd-networkd. See networkctl.
May 14 17:08:13 Zeus cat[273185]: OperationalState="routable"
May 14 17:08:13 Zeus cat[273185]: LINK=ens33dhclientFordhclientscripts will be executed (in the dirroutable.d) when the/var/lib/dhclient/dhclient.leasesfile gets modified bydhclientand lease information is passed to the scripts as environmental arguments.
Environment variables LINK, LINKINDEX= and DHCP lease information DHCP_LEASE= passed to the scripts.
When both interfaces are in same subnet and we have only one routing table with one GW, ie. traffic that reach via eth1 tries to leave via eth0(primary interface) which it can't. So we need to add a secondary routing table and routing policy so that the secondary interface uses the new custom routing table. Incase of static address the address and the routes already know. Incase of DHCP it's not predictable. When RoutingPolicyRules= is set, network-event-broker automatically configures the routing policy rules From and To ensuring traffic reaches via eth1 leaves via eth1.
❯ make build
❯ sudo make install
Due to security network-broker runs in non root user network-broker. It drops all privileges except CAP_NET_ADMIN and CAP_SYS_ADMIN.
❯ useradd -M -s /usr/bin/nologin network-brokerConfiguration file network-broker.toml located in /etc/network-broker/ directory to manage the configuration.
The [System] section takes following Keys:
LogLevel=Specifies the log level. Takes one of info, warn, error, debug and fatal. Defaults to info.
Generator= Specifies the network event generator source to listen. Takes one of systemd-networkd or dhclient. Defaults to systemd-networkd.
The [Network] section takes following Keys:
Links=A whitespace-separated list of links whose events should be monitored. Defaults to unset.
RoutingPolicyRules=A whitespace-separated list of links for which routing policy rules would be configured per address. When set, network-broker automatically adds routing policy rules from and to in another routing table (ROUTE_TABLE_BASE = 9999 + ifindex). When these addresses are removed, the routing policy rules are also dropped. Defaults to unset.
EmitJSON=A boolean. When true, JSON format data will be emitted via envorment variable JSON= Applies only for systemd-networkd. Defaults to true.
{
"Index": 3,
"MTU": 1500,
"TxQLen": 1000,
"Name": "ens37",
"AlternativeNames": "",
"HardwareAddr": "00:0c:29:5f:d1:43",
"Flags": "up|broadcast|multicast",
"RawFlags": 69699,
"ParentIndex": 0,
"MasterIndex": 0,
"Namespace": "",
"Alias": "",
"Statistics": {
"RxPackets": 573564,
"TxPackets": 373642,
"RxBytes": 540984229,
"TxBytes": 65923722,
"RxErrors": 0,
"TxErrors": 0,
"RxDropped": 0,
"TxDropped": 0,
"Multicast": 0,
"Collisions": 0,
"RxLengthErrors": 0,
"RxOverErrors": 0,
"RxCrcErrors": 0,
"RxFrameErrors": 0,
"RxFifoErrors": 0,
"RxMissedErrors": 0,
"TxAbortedErrors": 0,
"TxCarrierErrors": 0,
"TxFifoErrors": 0,
"TxHeartbeatErrors": 0,
"TxWindowErrors": 0,
"RxCompressed": 0,
"TxCompressed": 0
},
"Promisc": 0,
"Xdp": {
"Fd": 0,
"Attached": false,
"Flags": 0,
"ProgId": 0
},
"EncapType": "ether",
"Protinfo": "",
"OperState": "up",
"NetNsID": 0,
"NumTxQueues": 1,
"NumRxQueues": 1,
"GSOMaxSize": 65536,
"GSOMaxSegs": 65535,
"Group": 0,
"Slave": "",
"KernelOperState": "up",
"AddressState": "routable",
"CarrierState": "carrier",
"Driver": "e1000",
"IPv4AddressState": "routable",
"IPv6AddressState": "off",
"LinkFile": "",
"Model": "82545EM Gigabit Ethernet Controller (Copper)",
"OnlineState": "online",
"OperationalState": "routable",
"Path": "pci-0000:02:05.0",
"SetupState": "configuring",
"Type": "ether",
"Vendor": "Intel Corporation",
"ProductID": "100f",
"Manufacturer": "",
"NetworkFile": "/etc/systemd/network/10-ens37.network",
"DNS": [
"172.16.130.2"
],
"Domains": null,
"NTP": null,
"Address": [
{
"IP": "172.16.130.144",
"Mask": 24,
"Label": "ens37",
"Flags": 0,
"Scope": 0,
"Peer": "",
"Broadcast": "172.16.130.255",
"PreferedLft": 1800,
"ValidLft": 1800
},
{
"IP": "fe80::20c:29ff:fe5f:d143",
"Mask": 64,
"Label": "",
"Flags": 192,
"Scope": 253,
"Peer": "",
"Broadcast": "",
"PreferedLft": 4294967295,
"ValidLft": 4294967295
}
],
"Routes": [
{
"Scope": 0,
"Dst": {
"IP": "",
"Mask": 0
},
"Src": "172.16.130.144",
"Gw": "172.16.130.2",
"MultiPath": "",
"Protocol": 16,
"Priority": 1024,
"Table": 254,
"Type": 1,
"Tos": 0,
"Flags": null,
"MPLSDst": "",
"NewDst": "",
"Encap": "",
"MTU": 0,
"AdvMSS": 0,
"Hoplimit": 0
},
{
"Scope": 253,
"Dst": {
"IP": "172.16.130.0",
"Mask": 24
},
"Src": "172.16.130.144",
"Gw": "",
"MultiPath": "",
"Protocol": 2,
"Priority": 1024,
"Table": 254,
"Type": 1,
"Tos": 0,
"Flags": null,
"MPLSDst": "",
"NewDst": "",
"Encap": "",
"MTU": 0,
"AdvMSS": 0,
"Hoplimit": 0
},
{
"Scope": 253,
"Dst": {
"IP": "172.16.130.2",
"Mask": 32
},
"Src": "172.16.130.144",
"Gw": "",
"MultiPath": "",
"Protocol": 16,
"Priority": 1024,
"Table": 254,
"Type": 1,
"Tos": 0,
"Flags": null,
"MPLSDst": "",
"NewDst": "",
"Encap": "",
"MTU": 0,
"AdvMSS": 0,
"Hoplimit": 0
},
{
"Scope": 0,
"Dst": {
"IP": "fe80::",
"Mask": 64
},
"Src": "",
"Gw": "",
"MultiPath": "",
"Protocol": 2,
"Priority": 256,
"Table": 254,
"Type": 1,
"Tos": 0,
"Flags": null,
"MPLSDst": "",
"NewDst": "",
"Encap": "",
"MTU": 0,
"AdvMSS": 0,
"Hoplimit": 0
}
]
}
UseDNS=A boolean. When true, the DNS server will be se to systemd-resolved vis DBus. Applies only for DHClient. Defaults to false.
UseDomain=A boolean. When true, the DNS domains will be sent to systemd-resolved vis DBus. Applies only for DHClient. Defaults to false.
UseHostname=A boolean. When true, the host name be sent to systemd-hostnamed vis DBus. Applies only for DHClient. Defaults to false.
❯ sudo cat /etc/network-broker/network-broker.toml
[System]
LogLevel="debug"
Generator="systemd-networkd"
[Network]
Links="eth0 eth1"
RoutingPolicyRules="eth1"
UseDNS="true"
UseDomain="true"
EmitJSON="true"
❯ systemctl status network-broker.service
● network-broker.service - A daemon configures network upon events
Loaded: loaded (/usr/lib/systemd/system/network-broker.service; disabled; vendor preset: disabled)
Active: active (running) since Thu 2022-06-03 22:22:38 CEST; 3h 13min ago
Docs: man:networkd-broker.conf(5)
Main PID: 572392 (network-broker)
Tasks: 7 (limit: 9287)
Memory: 6.2M
CPU: 319ms
CGroup: /system.slice/network-broker.service
└─572392 /usr/bin/network-broker
Jun 04 01:36:04 Zeus network-broker[572392]: [info] 2022/06/04 01:36:04 Link='ens33' ifindex='2' changed state 'OperationalState'="carrier"
Jun 04 01:36:04 Zeus network-broker[572392]: [info] 2022/06/04 01:36:04 Link='' ifindex='1' changed state 'OperationalState'="carrier"
DBus signals generated by systemd-networkd
&{:1.683 /org/freedesktop/network1/link/_32 org.freedesktop.DBus.Properties.PropertiesChanged [org.freedesktop.network1.Link map[AdministrativeState:"configured"] []] 10}‣ Type=signal Endian=l Flags=1 Version=1 Cookie=24 Timestamp="Sun 2022-05-16 08:06:05.905781 UTC"
Sender=:1.292 Path=/org/freedesktop/network1 Interface=org.freedesktop.DBus.Properties Member=PropertiesChanged
UniqueName=:1.292
MESSAGE "sa{sv}as" {
STRING "org.freedesktop.network1.Manager";
ARRAY "{sv}" {
DICT_ENTRY "sv" {
STRING "OperationalState";
VARIANT "s" {
STRING "degraded";
};
};
};
ARRAY "s" {
};
};
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slack channel #photon.