On Wednesday 15 January 2003 10:08 am, Rob Sterenborg wrote: > > I have made two NAT box for a special dialup server. > > I have create an iptables stratup script like that.. > > > > /usr/local/sbin/iptables -t nat -A POSTROUTING -s > > 10.20.2.0/23 -o eth0 -j SNAT --to PUBLIC-IP1 > > /usr/local/sbin/iptables -t nat -A POSTROUTING -s > > 10.20.4.0/23 -o eth0 -j SNAT --to PUBLIC-IP2 > > /usr/local/sbin/iptables -t nat -A POSTROUTING -s > > 10.20.6.0/23 -o eth0 -j SNAT --to PUBLIC-IP3 > > /usr/local/sbin/iptables -t nat -A POSTROUTING -s > > 10.20.8.0/23 -o eth0 -j SNAT --to PUBLIC-IP4 > > /usr/local/sbin/iptables -t nat -A POSTROUTING -s > > 10.20.10.0/23 -o eth0 -j SNAT --to PUBLIC-IP5 > > /usr/local/sbin/iptables -t nat -A POSTROUTING -s > > 10.20.12.0/23 -o eth0 -j SNAT --to PUBLIC-IP6 > > /usr/local/sbin/iptables -t nat -A POSTROUTING -s > > 10.20.14.0/23 -o eth0 -j SNAT --to PUBLIC-IP7 > > > > and so on.. > > Is that /23 or /24 ? > I think that 10.20.0.0/23 does not cover all of 10.20.2.0/23, > 10.20.4.0/23, etc... > If you're trying to capture all the nets into 1 rule then you'd need a > mask of 10.20.0.0/255.255.0.0, which is 10.20.0.0/16. This will work for what he appears to be trying to do. He's trying to capture 512 addresses in each rule. A network defined as 10.20.2.0/23 will catch 10.20.2.0-10.20.2.255 and 10.20.3.0-10.20.3.255. /24 would specify that the first three numbers must match exactly. /23 means that the third can vary in only the least significant bit, IE .128 and .129, .16 and .17. http://www.wildpackets.com/products In the lower-right they have a free subnet calculator for Windows (which I see you're emailing from) and also one for PalmOS. Really handy, that PalmOS one is. Apart from that, a quick Google will find several subnet mask calculators, several platform-independant online ones. As Arnt Karlsen added in his reply: > ..output of: $ ipcalc -bnmp 10.20.2.0/23 > NETMASK=255.255.254.0 > PREFIX=23 > BROADCAST=10.20.3.255 > NETWORK=10.20.2.0 And to this I have to add that the same results derive from 10.20.3.0/23 j
