here is a rudimentry script that i am using at the moment to bring up the tunnel ...
the tunnel is defined as a link between the 2 internet addresses [external only so nat is not a issue] to keep it simple and to be able to have 2 networks with the same network range talk to each other i use a unique subnet for inter connection on this link (255.255.255.252 net mask) so there will be 1 unique address each side ...
if the networks are numbered the same NAT/PROXING MUST be used to have machines on the network talk to each other
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
#Configure Tunnel tun0
LOCAL=`ip addr show dev <DEVICE TO ATTACH TO (ppp0)> |grep inet |head -1 |cut -d/ -f1 |awk '{print $2}'`
REMOTEIP=`dig +short <REMOTE HOSTNAME SO DYNDNS WILL WORK> A IN |tail -1`
SR=`ping -c 3 <REMOTE LINK IP> |grep "packet loss" |awk '{print $7}'`
if [ "$SR" != "0%" ];then
/sbin/ip link set tun0 down
/sbin/ip tun del tun0
/sbin/ip tunnel add tun0 mode gre remote $REMOTEIP local $LOCAL ttl 255
/sbin/ip addr add <LOCAL LINK IP>/30 dev tun0
/sbin/ip link set tun0 up
fi;
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
