dhcpcd 是一个符合RFC1541 标准的DHCP 客户端程序。
dhcpcd [-bdeknpqABDEGKLTV] [-c, --script script] [-f, --config file] [-h, --hostname hostname] [-i, --vendorclassid vendorclassid] [-l, --leasetime seconds] [-m, --metric metric] [-o, --option option] [-r, --request address] [-s, --inform address[/cidr]] [-t, --timeout seconds] [-u, --userclass class] [-v, --vendor code, value] [-y, --reboot seconds] [-z, --allowinterfaces pattern] [-C, --nohook hook] [-F, --fqdn FQDN] [-I, --clientid clientid] [-O, --nooption option] [-Q, --require option] [-S, --static value] [-X, --blacklist address[/cidr]] [-Z, --denyinterfaces pattern] [interface] [...] dhcpcd -k, --release [interface] dhcpcd -x, --exit [interface]
-t, --timeout seconds Timeout after seconds, instead of the default 30. A setting of 0 seconds causes dhcpcd to wait forever to get a lease.
-b, --background Background immediately. This is useful for startup scripts which don't disable link messages for carrier status. -c, --script script Use this script instead of the default /libexec/dhcpcd-run-hooks. -d, --debug Echo debug and informational messages to the console. Subsequent debug options stop dhcpcd from daemonising. -e, --reconfigure dhcpcd will re-apply IP address, routing and run dhcpcd-run-hooks(8) for each interface. This is useful so that a 3rd party such as PPP or VPN can change the routing table and / or DNS, etc and then instruct dhcpcd to put things back after- wards. dhcpcd does not read a new configuration when this hap- pens - you should rebind if you need that functionality. -f, --config file Specify a config to load instead of /etc/dhcpcd.conf. dhcpcd always processes the config file before any command line options. -h, --hostname hostname By default, dhcpcd sends the current hostname to the DHCP server so it can register in DNS. You can use this option to specify the hostname sent, or an empty string to stop any hostname from being sent. -i, --vendorclassid vendorclassid Override the vendorclassid field sent. The default is dhcpcd <version>. If not set then none is sent. -k, --release This causes an existing dhcpcd process running on the interface to release its lease, deconfigure the interface and then exit. dhcpcd then waits until this process has exited. -l, --leasetime seconds Request a specific lease time in seconds. By default dhcpcd does not request any lease time and leaves the it in the hands of the DHCP server. -m, --metric metric Metrics are used to prefer an interface over another one, lowest wins. dhcpcd will supply a default metic of 200 + if_nametoindex(3). An extra 100 will be added for wireless interfaces. -o, --option option Request the DHCP option variable for use in /libexec/dhcpcd-run-hooks. -n, --rebind Notifies an existing dhcpcd process running on the interface to rebind it's lease. dhcpcd will not re-configure itself or use any other command line arguments. dhcpcd will timeout the rebind after 30 seconds at which point the lease will be expired and dhcpcd will enter the discovery state to obtain a new lease. Use the -t, --timeout option to change this. If dhcpcd is not run- ning, then it starts up as normal. This option used to be renew, but rebind is more accurate as we need to broadcast the request instead of unicasting. -p, --persistent dhcpcd normally deconfigures the interface and configuration when it exits. Sometimes, this isn't desirable if for example you have root mounted over NFS. You can use this option to stop this from happening. -r, --request [address] dhcpcd normally sends a DHCP DISCOVER to find servers to offer an address. dhcpcd then requests the address used. You can use this option to skip the BROADCAST step and just request the address. The downside is if you request an address the DHCP server does not know about or the DHCP server is not authorative, it will remain silent. In this situation, we go back to the init state and DISCOVER again. If no address is given then the first address currently assigned to the interface is used. -s, --inform [address[/cidr]] Behaves like -r, --request as above, but sends a DHCP INFORM instead of a REQUEST. This does not get a lease as such, just notifies the DHCP server of the address in use. You should also include the optional cidr network number in-case the address is not already configured on the interface. dhcpcd remains running and pretends it has an infinite lease. dhcpcd will not de-con- figure the interface when it exits. If dhcpcd fails to contact a DHCP server then it returns a failure instead of falling back on IPv4LL. -t, --timeout seconds Timeout after seconds, instead of the default 30. A setting of 0 seconds causes dhcpcd to wait forever to get a lease. -u, --userclass class Tags the DHCP message with the userclass class. DHCP servers use this give members of the class DHCP options other than the default, without having to know things like hardware address or hostname. -v, --vendor code,value Add an enscapulated vendor option. code should be between 1 and 254 inclusive. Examples. Set the vendor option 01 with an IP address. dhcpcd -v 01,192.168.0.2 eth0 Set the vendor option 02 with a hex code. dhcpcd -v 02,01:02:03:04:05 eth0 Do the above and set a third option with a string and not an IP address. dhcpcd -v 01,192.168.0.2 -v 02,01:02:03:04:05 -v 03,\"192.168.0.2\" eth0 -x, --exit This will signal an existing dhcpcd process running on the interface to deconfigure the interface and exit. dhcpcd then waits until this process has exited. -y, --reboot seconds Allow reboot seconds before moving to the discover phase if we have an old lease to use. The default is 10 seconds. A setting if 0 seconds causes dhcpcd to skip the reboot phase and go straight into discover. -D, --duid Generate an RFC 4361 compliant clientid. This requires persis- tent storage and not all DHCP servers work with it so it's not enabled by default. dhcpcd generates the DUID and stores in it /etc/dhcpcd.duid This file should not be copied to other hosts. -E, --lastlease If dhcpcd cannot obtain a lease, then try to use the last lease acquired for the interface. If the -p, --persistent option is not given then the lease is used if it hasn't expired. -F, --fqdn fqdn Requests that the DHCP server updates DNS using FQDN instead of just a hostname. Valid values for fqdn are disable, none, ptr and both. dhcpcd itself never does any DNS updates. dhcpcd encodes the FQDN hostname as specified in RFC1035. -I, --clientid clientid Send the clientid. If the string is of the format 01:02:03 then it is encoded as hex. For interfaces whose hardware address is longer than 8 bytes, or if the clientid is an empty string then dhcpcd sends a default clientid of the hardware family and the hardware address. Restricting behaviour dhcpcd will try to do as much as it can by default. However, there are sometimes situations where you don't want the things to be configured exactly how the the DHCP server wants. Here are some options that deal with turning these bits off. -q, --quiet Quiet dhcpcd on the command line, only warnings and errors will be displayed. The messages are still logged though. -z, --allowinterfaces pattern When discovering interfaces, the interface name must match pattern which is a space or comma separated list of patterns passed to fnmatch(3). If the same interface is matched in -Z, --denyinterfaces then it is still denied. -A, --noarp Don't request or claim the address by ARP. This also disables IPv4LL. -B, --nobackground Don't run in the background when we acquire a lease. This is mainly useful for running under the control of another process, such as a debugger or a network manager. -C, --nohook script Don't run this hook script. Matches full name, or prefixed with 2 numbers optionally ending with .sh. So to stop dhcpcd from touching your DNS or MTU settings you would do:- dhcpcd -C resolv.conf -C mtu eth0 -G, --nogateway Don't set any default routes. -K, --nolink Don't receive link messages for carrier status. You should only have to use this with buggy device drivers or running dhcpcd through a network manager. -L, --noipv4ll Don't use IPv4LL (aka APIPA, aka Bonjour, aka ZeroConf). -O, --nooption option Don't request the specified option. If no option given, then don't request any options other than those to configure the interface and routing. -Q, --require option Requires the option to be present in all DHCP messages, otherwise the message is ignored. To enforce that dhcpcd only responds to DHCP servers and not BOOTP servers, you can -Q dhcp_message_type. -S, --static value Configures a static value. If you set ip_address then dhcpcd will not attempt to obtain a lease and just use the value for the address with an infinite lease time. Here is an example which configures a static address, routes and dns. dhcpcd -S ip_address=192.168.0.10/24 \ -S routers=192.168.0.1 \ -S domain_name_servers=192.168.0.1 \ eth0 -T, --test On receipt of OFFER messages just call /libexec/dhcpcd-run-hooks with the reason of TEST which echo's the DHCP variables found in the message to the console. The interface configuration isn't touched and neither are any configuration files. -V, --variables Display a list of option codes and the associated variable for use in dhcpcd-run-hooks(8). Variables are prefixed with new_ and old_ unless the option number is -. Variables without an option are part of the DHCP message and cannot be directly requested. -X, --blacklist address[/cidr] Ignore all packets from address[/cidr]. -Z, --denyinterfaces pattern When discovering interfaces, the interface name must not match pattern which is a space or comma separated list of patterns passed to fnmatch(3).