dhcpcd - DHCP client daemon


SYNOPSIS

       dhcpcd  [-dknrBCDHRT] [-t timeout] [-c filename] [-h host­
            name] [-i vendorClassID] [-I clientID] [-l leasetime]
            [-s [ipaddr]] [-w windowsize] [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.

              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,  notably  those  used  by  @Home Networks,
              require the hostname option field containing a spe­
              cific 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,  system 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

              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.

       -w windowsize
              Specifies  the  window  size for the gateway route.
              Default = 32768.

       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.

              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>


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