Date: Thu, 04 Mar 2004 11:58:26 +0100 From: Sasa Stupar <sasa@stupar.homelinux.net> To: FreeBSD-config ML <freebsd-config@freebsd.org> Subject: Re: NAT onto same network? Message-ID: <40470BD2.9000001@stupar.homelinux.net> In-Reply-To: <49386.141.67.67.161.1078396444.squirrel@Matrix.Iceman> References: <4046FDDA.7080908@stupar.homelinux.net> <49386.141.67.67.161.1078396444.squirrel@Matrix.Iceman>
next in thread | previous in thread | raw e-mail | index | archive | help
OK, webservers ip is 192.168.10.10, internal IP on nat machine is 192,168.10.111, all users have ip in the range 192.168.10.0/24 mask 255.255.255.0. They are all connected to the switch. Here is what is says about it but for iptables on linux: -------- 10. Destination NAT Onto the Same Network If you are doing port forwarding back onto the same network, you need to make sure that both future packets and reply packets pass through the NAT box (so they can be altered). The NAT code will now (since 2.4.0-test6), block the outgoing ICMP redirect which is produced when the NAT'ed packet heads out the same interface it came in on, but the receiving server will still try to reply directly to the client (which won't recognize the reply). The classic case is that internal staff try to access your `public' web server, which is actually DNAT'ed from the public address (1.2.3.4) to an internal machine (192.168.1.1), like so: # iptables -t nat -A PREROUTING -d 1.2.3.4 \ -p tcp --dport 80 -j DNAT --to 192.168.1.1 One way is to run an internal DNS server which knows the real (internal) IP address of your public web site, and forward all other requests to an external DNS server. This means that the logging on your web server will show the internal IP addresses correctly. The other way is to have the NAT box also map the source IP address to its own for these connections, fooling the server into replying through it. In this example, we would do the following (assuming the internal IP address of the NAT box is 192.168.1.250): # iptables -t nat -A POSTROUTING -d 192.168.1.1 -s 192.168.1.0/24 \ -p tcp --dport 80 -j SNAT --to 192.168.1.250 Because the PREROUTING rule gets run first, the packets will already be destined for the internal web server: we can tell which ones are internally sourced by the source IP addresses. ---------------- Thank you, Sasa Frank Mueller pravi: > Maybe you should give a little more information, what exactly you're trying to do. > Subnets? Netmasks? Webserver physically only connected to Gateway??? > > Bye, > > Frank > > >>Hi! >> >>I have manage to configure NAT, port forwarding and firewall on my new >>gateway machine. Now I am stuck with configuring nat onto same network. >>I need it so LAN users can access webserver which is also on the LAN (it >>has configured multiple virtual hosts). >>Can anyone help me with this? >> >>Thank you, >>Sasa
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?40470BD2.9000001>