Why do u say i should not use dnat? U also sais that my second example is correct.. havent u see that uses also dnat.. I think i should use dnat because i want to alter the ip packet so as to be forwarded to the other network.. Isn't that correct? --- "John A. Sullivan III" <jsullivan@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 2005-09-27 at 07:57 -0700, Alaios wrote: > > Hi plz take a look at the following example > > > > The laptop has 2 ethernet interfaces > > To eth1 comes traffic from src 143.233.222.253 > > The eth0 has ip address 10.2.4.2 and it is > connected > > back to back with eth1 of other pc with ip address > > 10.2.4.1 > > I want to forward the traffic with src > 143.233.222.253 > > to the 10.2.4.1 pc and if it works i will redo > this > > for a second pc so as to l send the traffic to a > third > > on. > > Can u help me plz? > > > > I have tried this one > > iptables -t nat -A PREROUTING -i eth1 -s > > 143.233.222.253 -j DNAT --to-destination 10.2.4.1 > > i have also set the > > /proc/sys/net/ipv4/ip_forward to 1 > > but still i cant see any trafiic to eth0 interface > (ip > > 10.2.4.2) > > > > > > I have also tested this one > > iptables -t nat -A PREROUTING -p tcp -d > 143.233.222.77 > > (laptop eth1 card) --dport 22453 (i have cheched > dst > > port with tcpdump) 00 -j DNAT --to-destination > > 10.2.4.1 > > this still doesnt work > > Every time i try to apply a new rule i use first > > the iptables -F > > iptables -t nat -F command > <snip> > > I'm a little confused about what you are doing. I > would normally refer > you to Oskar Andreasson's excellent tutorial at > http://iptables-tutorial.frozentux.net/iptables-tutorial.html > or the > training slides on the ISCS web site > (http://iscs.sourceforge.net) but, > since it appears that you have an emergency, here > goes: > > First, if the source is 143.233.222.253, you would > not want to DNAT it. > DNAT changes the destination. Thus, your second > attempt is the correct > one. You might want to lock the destination port - > it's not likely to > be a problem but, if it ever is, it will be one of > those really hard to > diagnose, sporadic problems: > -j DNAT --to-destination 10.2.4.1:22453 > > Second, this only takes care of the addressing. You > must still allow > the traffic in the FORWARD chain of the filter > table, e.g., > > iptables -A FORWARD -d 10.2.4.1 -p 6 --dport 22453 > -j ACCEPT > > Hope this helps - John > -- > John A. Sullivan III > Open Source Development Corporation > +1 207-985-7880 > jsullivan@xxxxxxxxxxxxxxxxxxx > > If you would like to participate in the development > of an open source > enterprise class network security management system, > please visit > http://iscs.sourceforge.net > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
