Mercurial > hg > dhcpcd

view README.md @ 5525:26b5d9bc2985 draft

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
privsep: Send all log messages to the privileged actioneer If dhcpcd starts and no syslogd implementation is running then various syscall filters could be triggered when dhcpcd wants to syslog and it's already in a chroot. Not all libc openlog implementations support LOG_NDELAY and openlog does not return an error code and can also mask errno back to 0. So we have no way of knowing if we have a syslog connection or not. This means we cannot cache the connection at startup because syslog itself will try and open if no connection. As such, all logging is now directed to the dhcpcd privileged actioneer process which will handle all the syslog and log file writing actions. The only downside of this approach (other than an extra fd per process) is that we no longer know which PID raised the message. While we could put the correct PID in the logfile as we control the API, we cannot put it into syslog as we cannot control that API. As all privsep errors should log which function they came from this will hopefully not be an issue as on the happy path only the master process will log stuff.
author Roy Marples <roy@marples.name>
date Fri, 30 Oct 2020 03:43:51 +0000
parents a351afa57787
children
line wrap: on
line source

# dhcpcd

dhcpcd is a
[DHCP](http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol) and a
[DHCPv6](http://en.wikipedia.org/wiki/DHCPv6) client.
It's also an IPv4LL (aka [ZeroConf](http://en.wikipedia.org/wiki/Zeroconf))
client.
In layman's terms, dhcpcd runs on your machine and silently configures your
computer to work on the attached networks without trouble and mostly without
configuration.

If you're a desktop user then you may also be interested in
[Network Configurator (dhcpcd-ui)](http://roy.marples.name/projects/dhcpcd-ui)
which sits in the notification area and monitors the state of the network via
dhcpcd.
It also has a nice configuration dialog and the ability to enter a pass phrase
for wireless networks.

dhcpcd may not be the only daemon running that wants to configure DNS on the
host, so it uses [openresolv](http://roy.marples.name/projects/openresolv)
to ensure they can co-exist.

See [BUILDING.md](BUILDING.md) for how to build dhcpcd.

If you wish to file a support ticket or help out with development, please
[visit the Development Area](https://dev.marples.name/project/profile/101/)
or join the mailing list below.

## Configuration

You should read the
[dhcpcd.conf man page](http://roy.marples.name/man/html5/dhcpcd.conf.html)
and put your options into `/etc/dhcpcd.conf`.
The default configuration file should work for most people just fine.
Here it is, in case you lose it.

```
# A sample configuration for dhcpcd.
# See dhcpcd.conf(5) for details.

# Allow users of this group to interact with dhcpcd via the control socket.
#controlgroup wheel

# Inform the DHCP server of our hostname for DDNS.
hostname

# Use the hardware address of the interface for the Client ID.
#clientid
# or
# Use the same DUID + IAID as set in DHCPv6 for DHCPv4 ClientID as per RFC4361.
# Some non-RFC compliant DHCP servers do not reply with this set.
# In this case, comment out duid and enable clientid above.
duid

# Persist interface configuration when dhcpcd exits.
persistent

# Rapid commit support.
# Safe to enable by default because it requires the equivalent option set
# on the server to actually work.
option rapid_commit

# A list of options to request from the DHCP server.
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes
# Respect the network MTU. This is applied to DHCP routes.
option interface_mtu

# Most distributions have NTP support.
#option ntp_servers

# A ServerID is required by RFC2131.
require dhcp_server_identifier

# Generate SLAAC address using the Hardware Address of the interface
#slaac hwaddr
# OR generate Stable Private IPv6 Addresses based from the DUID
slaac private
```

The [dhcpcd man page](/man/html8/dhcpcd.html) has a lot of the same options and more, which only apply to calling dhcpcd from the command line.


## Compatibility
dhcpcd-5 is only fully command line compatible with dhcpcd-4
For compatibility with older versions, use dhcpcd-4

## Upgrading
dhcpcd-7 defaults the database directory to `/var/db/dhcpcd` instead of
`/var/db` and now stores dhcpcd.duid and dhcpcd.secret in there instead of
in /etc.

dhcpcd-9 defaults the run directory to `/var/run/dhcpcd` instead of
`/var/run` and the prefix of dhcpcd has been removed from the files.

## ChangeLog
We no longer supply a ChangeLog.
However, you're more than welcome to read the
[commit log](http://roy.marples.name/git/dhcpcd.git/log/) and
[archived release announcements](http://roy.marples.name/archives/dhcpcd-discuss/).