dhcpcd
dhcpcd(8) Linux System Manager's Manual dhcpcd(8)NAME
dhcpcd - DHCP client daemonSYNOPSIS
dhcpcd [-dknrBCDHRT] [-t timeout] [-c filename] [-h hostname] [-i vendorClassID] [-I clientID] [-l leasetime] [-s [ipaddr]] [interface]DESCRIPTION
dhcpcd is an implementation of the DHCP client specified in RFC2131 (when -r option is not specified) and RFC1541 (when -r option is specified). It gets the host information (IP address, netmask, broad cast address, etc.) from a DHCP server and configures the network interface of the machine on which it is running. It also tries to renew the lease time according to RFC2131 or RFC1541 (obsolete).OPTIONS
-d With this flag dhcpcd will syslog(LOG_DEBUG,...) messages for about every step it does. It's recom mended to use this option since it doesn't really produce too much output but will greatly help in resolving a problems if any. -k Sends SIGHUP signal to the dhcpcd process that is currently running. If dhcpcd receives SIGHUP it will send DCHP_RELEASE message to the server and destroy dhcpcd cache. In a case dhcpcd receives SIGTERM which is normally used by shutdown(8) when rebooting the system dhcpcd will not send DHCP_RELEASE and will not destroy cache. When sys tem boots dhcpcd will use cache to request the same IP address from DHCP server which was assigned before the system went down. -n Sends SIGALRM signal to the dhcpcd process that is currently running which forces dhcpcd to try to renew the lease. If dhcpcd is not running, the flag is ignored and dhcpcd follows the normal startup procedure. -r Makes dhcpcd RFC1541 (obsolete) compliant. dhcpcd is RFC2131 compliant unless this option is speci fied. -B Requests broadcast response from DHCP server. -C Forces dhcpcd to calculate checksum on received packets. -D Forces dhcpcd to set domainname of the host to the domainname option supplied by DHCP server. By default dhcpcd will NOT set domainname of the host to the domainname option received from DHCP server. -H Forces dhcpcd to set hostname of the host to the hostname option supplied by DHCP server. By default dhcpcd will NOT set hostname of the host to the hostname option received from DHCP server. -R Prevents dhcpcd from replacing existing /etc/resolv.conf file. -T Test case, when dhcpcd goes through the DHCP nego tiation sequence but doesn't actually configure the interface or otherwise change anything on the sys tem. Used primarily for testing DHCP servers. -t timeout Specifies (in seconds ) for how long dhcpcd will try to get an IP address. The default is 60 sec onds. dhcpcd will not fork into background until it gets a valid IP address in which case dhcpcd will return 0 to the parent process. In a case dhcpcd times out before receiving a valid IP address from DHCP server dhcpcd will return exit code 1 to the parent process. -c filename Deprecated option provided for compatibility with dhcpcd v.0.70. dhcpcd will try to execute filename after it configures the interface. -h hostname specifies a string used for the hostname option field when dhcpcd sends DHCP messages. Some DHCP servers require the hostname option field contain ing a specific string in the DHCP messages from clients. -i vendorClassID Specifies the vendor class identifier string. dhcpcd uses the default vendor class identifier string (system name, sytem release, and machine type) if it is not specified. -I clientID Specifies the client identifier string. dhcpcd uses the default client identifier (Ethernet Address of the network interface) if it is not specified. -l leasetime Specifies (in seconds) the recommended lease time to the server. (Note that the server can override this value if it sees fit). This value is used in the DHCP_DISCOVER message. The default is infinite (0xffffffff). -s [ipaddr] Sends DHCP_INFORM message to DHCP server using ipaddr. The optional ipaddr parameter must be in the form xxx.xxx.xxx.xxx. If no ipaddr parameter is given on the command line dhcpcd will use the IP address currently assigned to the interface. If there is no IP address currently assigned to the interface dhcpcd will use previously obtained IP address stored in /etc/dhcpc/dhcpcd-<inter face>.cache file. interface Specifies the network interface name (eth0, eth1, etc.). dhcpcd uses the network interface eth0 unless an explicit name is specified.FILES
/etc/dhcpc directory used for storing files created by dhcpcd /etc/dhcpc/dhcpcd-<interface>.info file in which dhcpcd saves the host information. The word interface is actually replaced with the network interface name like eth0 to which dhcpcd is attached. /etc/dhcpc/dhcpcd-<interface>.exe file which dhcpcd will try to execute whenever it detects a change in IP address. /etc/resolv.conf file created by dhcpcd when the client receives DNS and domain name options. The old /etc/resolv.conf file will be renamed to /etc/resolv.conf.sv and will be restored back when dhcpcd exits for any reason. /var/run/dhcpcd-<interface>.pid file containing the process id of dhcpcd. The word interface is actually replaced with the network interface name like eth0 to which dhcpcd is attached. /etc/dhcpc/dhcpcd-<interface>.cache Cache file containing the previously assigned IP address and some other things. The word interface is actually replaced with the network interface name like eth0 to which dhcpcd is attached.SEE ALSO
Dynamic Host Configuration Protocol, RFC2131 and RFC1541 (obsolete) DHCP Options and BOOTP Vendor Extensions, RFC2132 BUGS dhcpcd uses time(3) to calculate the lease expiration time. If the system time is changed while the client is running, the lease expiration time may not be predictable.AUTHORS
v.<1.3 Yoichi Hariguchi <yoichi@fore.com> v.1.3 Sergei Viznyuk <sv@phystech.com> dhcpcd 1.3 31 January 1998 dhcpcd(8)