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Annotation of embedaddon/dnsmasq/contrib/port-forward/dnsmasq-portforward, revision 1.1.1.1

1.1       misho       1: #!/bin/bash
                      2: # 
                      3: # /usr/sbin/dnsmasq-portforward
                      4: #
                      5: # A script which gets run when the dnsmasq DHCP lease database changes.
                      6: # It logs to $LOGFILE, if it exists, and maintains port-forwards using
                      7: # IP-tables so that they always point to the correct host. See
                      8: # $PORTSFILE for details on configuring this. dnsmasq must be version 2.34 
                      9: # or later.
                     10: #
                     11: # To enable this script, add 
                     12: #    dhcp-script=/usr/sbin/dnsmasq-portforward
                     13: # to /etc/dnsmasq.conf
                     14: #
                     15: # To enable logging, touch $LOGFILE
                     16: #
                     17: 
                     18: PORTSFILE=/etc/portforward
                     19: LOGFILE=/var/log/dhcp.log
                     20: IPTABLES=/sbin/iptables
                     21: 
                     22: action=${1:-0}
                     23: hostname=${4}
                     24: 
                     25: # log what's going on.
                     26: if [ -f ${LOGFILE} ] ; then
                     27:     date +"%D %T $*" >>${LOGFILE}
                     28: fi
                     29: 
                     30: # If a lease gets stripped of a name, we see that as an "old" action
                     31: # with DNSMASQ_OLD_HOSTNAME set, convert it into a "del" 
                     32: if [ ${DNSMASQ_OLD_HOSTNAME} ] && [ ${action} = old ] ; then
                     33:     action=del
                     34:     hostname=${DNSMASQ_OLD_HOSTNAME}
                     35: fi
                     36: 
                     37: # IPv6 leases are not our concern. no NAT there!
                     38: if [ ${DNSMASQ_IAID} ] ; then
                     39:    exit 0
                     40: fi
                     41: 
                     42: # action init is not relevant, and will only be seen when leasefile-ro is set.
                     43: if [ ${action} = init ] ; then
                     44:     exit 0
                     45: fi
                     46: 
                     47: # action tftp is not relevant.
                     48: if [ ${action} = tftp ] ; then
                     49:     exit 0
                     50: fi
                     51: 
                     52: if [ ${hostname} ]; then
                     53:     ports=$(sed -n -e "/^${hostname}\ .*/ s/^.* //p" ${PORTSFILE})
                     54: 
                     55:     for port in $ports; do
                     56:        verb=removed
                     57:        protocol=tcp
                     58:        if [ ${port:0:1} = u ] ; then
                     59:            protocol=udp 
                     60:            port=${port/u/}
                     61:        fi
                     62:        src=${port/:*/}
                     63:        dst=${port/*:/}
                     64: # delete first, to avoid multiple copies of rules.
                     65:        ${IPTABLES} -t nat -D PREROUTING -p $protocol --destination-port $src -j DNAT --to-destination ${3}:$dst
                     66:         if [ ${action} != del ] ; then
                     67:            ${IPTABLES} -t nat -A PREROUTING -p $protocol --destination-port $src -j DNAT --to-destination ${3}:$dst
                     68:            verb=added
                     69:        fi
                     70:        if [ -f ${LOGFILE} ] ; then
                     71:            echo "     DNAT $protocol $src to ${3}:$dst ${verb}." >>${LOGFILE}
                     72:        fi
                     73:     done
                     74: fi
                     75:     
                     76: exit 0
                     77: 
                     78: