GratisDNS.sh

#!/bin/sh

# User Configuration
__USERNAME__="MyUserName"
__PASSWORD__="MyPassword"
__HOSTNAME__="host.example.com"
__DOMAIN__=$(echo ${__HOSTNAME__} | cut -d. -f2-3)

# System Configuration
# Set the __INTERFACE__ varible to nothing (__INTERFACE__=) to use external lookup.
__INTERFACE__=eth1
__IP_CACHE__=/tmp/gratisdns_ddns_ip.txt
__LOGFILE__=/var/log/gratisdns_ddns.log


log() {
    __LOGTIME__=$(date +"%b %e %T")
    if [ "${#}" -lt 1 ]; then
        false
    else
        __LOGMSG__="${1}"
    fi
    if [ "${#}" -lt 2 ]; then
        __LOGPRIO__=7
    else
        __LOGPRIO__=${2}
    fi

    #logger -p ${__LOGPRIO__} -t "$(basename ${0})" "${__LOGMSG__}"
    echo "${__LOGTIME__} $(basename ${0}) (${__LOGPRIO__}): ${__LOGMSG__}" >> ${__LOGFILE__}
}

# Get the last known DDNS IP
if [ ! -f ${__IP_CACHE__} ]; then
    echo "127.0.0.1" > ${__IP_CACHE__}
fi
__OLDIP__=$(cat ${__IP_CACHE__})

if [ -z "${__INTERFACE__}" ]; then
    # Interface not defined, so getting the public IP through external lookup.
    __MYIP__=$(curl -s "http://automation.whatismyip.com/n09230945.asp")
else
    # Get the current IP for the specified interface.
    __MYIP__=$(ifconfig ${__INTERFACE__} | sed '/inet\ /!d;s/.*r://g;s/\ .*//g')
fi

if [ "${__OLDIP__}" == "${__MYIP__}" ]; then
    log "IP not changed. ${__MYIP__}. Not updating." 7
    true
else
    log "IP changed. ${__OLDIP__} > ${__MYIP__}. Attempting to update DNS." 6

    # Update DNS record
    __URL__="https://ssl.gratisdns.dk/ddns.phtml?u=${__USERNAME__}&p=${__PASSWORD__}&d=${__DOMAIN__}&h=${__HOSTNAME__}&i=${__MYIP__}"
    __STATUS__=$(curl -s -k "${__URL__}")
    case ${__STATUS__} in
        'OK<br>')
            echo ${__MYIP__} > ${__IP_CACHE__}
            log "IP successfully updated." 6
            true
            ;;
        'OK<br>Opdateret i forvejen')
            echo ${__MYIP__} > ${__IP_CACHE__}
            log "IP successfully updated. However, the IP was already updated, according to the DDNS provider." 5
            true
            ;;
        'Forkerte værdier, opdatering kan ikke laves.<br><br>A record findes ikke.')
            log "Invalid parameters, nothing was updated. The A record '${__HOSTNAME__}' doesn't exist." 3
            false
            ;;
        'Domæne kan IKKE administreres af bruger')
            log "You do not have permission to update DDNS for the domain '${__DOMAIN__}'." 3
            false
            ;;
        'Forkerte værdier, opdatering kan ikke laves.<br><br>A record findes ikke.Hostnavn er ulovligt.')
            log "Invalid parameters, nothing was updated. The A record for '${__HOSTNAME__}' doesn't exist. The hostname must be a FQDN." 3
            false
            ;;
        'Bruger login: 1Fejl i kodeord, prøv igen. Husk serveren ser forskel på STORE Og små BOGstAvER.')
            log "Incorrect password for '${__USERNAME__}'. The password is CaSe SeNsItIvE." 3
            false
            ;;
        'Bruger login: Bruger eksistere ikke, husk serveren ser forskel på STORE Og smÅ BOGstAvER.')
            log "The supplied username '${__USERNAME__}' wasn't found. The username is CaSe SeNsItIvE." 3
            false
            ;;
    esac
fi