pyroute2-dhcp-client

Synopsis

pyroute2-dhcp-client [OPTION]... <ifname>

Description

pyroute2-dhcp-client is a client based on the pyroute2 DHCP implementation.

It is mostly a simple CLI wrapper around the pyroute2.dhcp.client.AsyncDHCPClient class, which has more flexibility and configuration options (see pyroute2.dhcp.client.ClientConfig). Some options are not (yet) configurable through the commandline, such as the client and vendor IDs, the hostname and the requested parameters.

Its default behavior is to try to acquire a lease for the passed interface, configuring its IP address and gateway, as long as it is running. On exit, it releases its lease and remove the associated IP from the interface. If the interface goes down during the client's lifetime, or is not up when starting, the client waits until it is up again.

System configuration based on lease options (i.e. IP/gateway configuration) is done through hooks. The default hooks add the obtained IP to the interface and set the default gateway, but that can be configured, and you can ask the client to run your own custom hooks (see pyroute2.dhcp.hooks).

The client can also be started in "one-shot" mode (see the -x option), where it will exit as soon as a lease is obtained.

Available options:

--lease-type <type>

Class to use for leases. Must be a subclass of pyroute2.dhcp.leases.Lease.

--hook <hook>

Hooks to run on lease events, see pyroute2.dhcp.hooks.

--disable-hooks

Disable all hooks.

--exit-on-timeout <N>, -x <N>

Wait for max N seconds for a lease, exit if none could be obtained.

--log-level <level>

Logging level to use: DEBUG, INFO, WARNING, ERROR. The default is INFO.

--no-release, -R

Do not send a DHCPRELEASE on exit.

--write-pidfile, -p

Write a pid file in the working directory.

Leases

The default behavior is to write the latest obtained lease to a JSON file named after the interface in the client's working directory.

On startup, if the client finds such a file, it will request the same IP.

This behavior can be modified with the --lease-type option. For example, the pyroute2.dhcp.client.leases.JSONStdoutLease class just writes leases to standard output and does not persist them to disk.

Signals

pyroute2-dhcp-client responds to the following signals:

• SIGINT (i.e. Ctrl-C) releases & exits

• SIGUSR1 triggers a lease renewal (normally triggered automatically at ~50% of the lease time)

• SIGUSR2 triggers a rebinding (normally triggered automatically at ~87% of the lease time)

• SIGHUP forces the current lease to expire and starts looking for a new one

Examples

# pyroute2-dhcp-client --disable-hooks -R -x 5 eth0
...
# cat eth0.lease.json
{
  "ack": {
    "op": 2,
    "htype": 1,
    "hlen": 6,
    "hops": 0,
    "xid": 391458644,
    "secs": 0,
    "flags": 32768,
    "ciaddr": "0.0.0.0",
    "yiaddr": "192.168.124.180",
    "siaddr": "192.168.124.1",
    "giaddr": "0.0.0.0",
    "chaddr": "aa:80:fa:2c:49:a2",
    "sname": "",
    "file": "",
    "cookie": "63:82:53:63",
    "options": {
      "message_type": 5,
      "server_id": "192.168.124.1",
      "lease_time": 3600,
      "renewal_time": 1800,
      "rebinding_time": 3150,
      "subnet_mask": "255.255.255.0",
      "broadcast_address": "192.168.124.255",
      "router": [
        "192.168.124.1"
      ],
      "name_server": [
        "192.168.124.1"
      ]
    }
  },
  "interface": "eth0",
  "server_mac": "52:54:00:e9:d3:1d",
  "obtained": 1740562827.7350075
}