Utilizar Dyndns en Debian

Tengo una cuenta de DynDNS. En él guardo ciertas IPs, pero si no entras una vez al mes o algún Router refresca la información, la cuenta se cierra. Para solventar esto podemos usar ddclient. Aunque dispongo de IP estática, esto me mantendrá la cuenta activa.

Se instala el programa ddclient. Pregunta cosas como el usuario y password de la cuenta, también que interface se debe usar para actualizar la IP.

Todo perfecto, excepto porque la IP que refresca es la local. Para solventar esto podemos echarle un vistazo al fichero /etc/ddclient.conf.

Debemos cambiar el use=if, if=eth1

Si consultamos las opciones del programa, realmente hay mil maneras para averiguar la IP externa.

# ddclient -help
[...]
-use which            : how the should IP address be obtained. (default: ip).
-use=2wire                  : obtain IP from 2Wire 1701HG Gateway at the -fw {address}.
-use=3com-3c886a            : obtain IP from 3com 3c886a 56k Lan Modem at the -fw {address}.
-use=3com-oc-remote812      : obtain IP from 3com OfficeConnect Remote 812 at the -fw {address}.
-use=alcatel-510            : obtain IP from Alcatel Speed Touch 510 at the -fw {address}.
-use=alcatel-stp            : obtain IP from Alcatel Speed Touch Pro at the -fw {address}.
-use=allnet-1298            : obtain IP from Allnet 1298 at the -fw {address}.
-use=cayman-3220h           : obtain IP from Cayman 3220-H DSL at the -fw {address}.
-use=cisco                  : obtain IP from Cisco FW at the -fw {address}.
-use=cmd                    : obtain IP from the -cmd {external-command}.
-use=dlink-524              : obtain IP from D-Link DI-524 at the -fw {address}.
-use=dlink-604              : obtain IP from D-Link DI-604 at the -fw {address}.
-use=dlink-614              : obtain IP from D-Link DI-614+ at the -fw {address}.
-use=e-tech                 : obtain IP from E-tech Router at the -fw {address}.
-use=elsa-lancom-dsl10      : obtain IP from ELSA LanCom DSL/10 DSL FW at the -fw {address}.
-use=elsa-lancom-dsl10-ch01 : obtain IP from ELSA LanCom DSL/10 DSL FW (isdn ch01) at the -fw {address}.
-use=elsa-lancom-dsl10-ch02 : obtain IP from ELSA LanCom DSL/10 DSL FW (isdn ch01) at the -fw {address}.
-use=fw                     : obtain IP from the firewall specified by -fw {type|address}.
-use=if                     : obtain IP from the -if {interface}.
-use=ip                     : obtain IP from -ip {address}.
-use=linksys                : obtain IP from Linksys FW at the -fw {address}.
-use=linksys-rv042-wan1     : obtain IP from Linksys RV042 Dual Homed Router WAN Port 2 at the -fw {address}.
-use=linksys-rv042-wan2     : obtain IP from Linksys RV042 Dual Homed Router WAN Port 2 at the -fw {address}.
-use=linksys-ver2           : obtain IP from Linksys FW version 2 at the -fw {address}.
-use=linksys-ver3           : obtain IP from Linksys FW version 3 at the -fw {address}.
-use=linksys-wcg200         : obtain IP from Linksys WCG200 FW at the -fw {address}.
-use=linksys-wrt854g        : obtain IP from Linksys WRT854G FW at the -fw {address}.
-use=maxgate-ugate3x00      : obtain IP from MaxGate UGATE-3x00 FW at the -fw {address}.
-use=netcomm-nb3            : obtain IP from NetComm NB3 at the -fw {address}.
-use=netgear-dg834g         : obtain IP from netgear-dg834g at the -fw {address}.
-use=netgear-rp614          : obtain IP from Netgear RP614 FW at the -fw {address}.
-use=netgear-rt3xx          : obtain IP from Netgear FW at the -fw {address}.
-use=netgear-wgt624         : obtain IP from Netgear WGT624 at the -fw {address}.
-use=netgear-wpn824         : obtain IP from Netgear WPN824 FW at the -fw {address}.
-use=netopia-r910           : obtain IP from Netopia R910 FW at the -fw {address}.
-use=olitec-SX200           : obtain IP from olitec-SX200 at the -fw {address}.
-use=rtp300                 : obtain IP from Linksys RTP300 at the -fw {address}.
-use=sitecom-dc202          : obtain IP from Sitecom DC-202 FW at the -fw {address}.
-use=smc-barricade          : obtain IP from SMC Barricade FW at the -fw {address}.
-use=smc-barricade-7004vbr  : obtain IP from SMC Barricade FW (7004VBR model config) at the -fw {address}.
-use=smc-barricade-7401bra  : obtain IP from SMC Barricade 7401BRA FW at the -fw {address}.
-use=smc-barricade-alt      : obtain IP from SMC Barricade FW (alternate config) at the -fw {address}.
-use=sohoware-nbg800        : obtain IP from SOHOWare BroadGuard NBG800 at the -fw {address}.
-use=sveasoft               : obtain IP from Sveasoft WRT54G/WRT54GS at the -fw {address}.
-use=vigor-2200usb          : obtain IP from Vigor 2200 USB at the -fw {address}.
-use=watchguard-edge-x      : obtain IP from Watchguard Edge X FW at the -fw {address}.
-use=watchguard-soho        : obtain IP from Watchguard SOHO FW at the -fw {address}.
-use=web                    : obtain IP from an IP discovery page on the web.
-use=westell-6100           : obtain IP from Westell C90-610015-06 DSL Router at the -fw {address}.

-use=xsense-aero            : obtain IP from Xsense Aero at the -fw {address}.
[...]

En nuestro caso usaremos una Web que nos devuelva nuestra IP.

use=web, web=http://checkip.dyndns.org/, web-skip='Current IP Address: '

Daros cuenta que agregamos un texto de exclusión, ya que el principio de la frase que nos da la IP no nos interesa.

Todo listo, reiniciamos el servidor ddclient y ya está funcionando.