I our lab we have a small network of 4 Debian machines, connected through a router in a LAN. One of these machines (the server) have internet connection provided by the bigger network of the building. I want to give internet to the inner machines on LAN using NAT. I followed this guide but I cannot get a working connection from clients.
The IP of the server at eth0 is 192.168.2.248 (connected to the internet); and the eth1 is 192.168.200.1 (connected to the LAN). I setup bind9 (with standard conf, but adding the correct DNS addresses to /etc/bind/named.conf.options) to forward the DNS but I not sure if this is absolutely necessary.
$ iptables-save # Generated by iptables-save v1.4.21 on Mon Aug 22 16:06:21 2016 *nat :PREROUTING ACCEPT [46792:8129746] :INPUT ACCEPT [46302:8099043] :OUTPUT ACCEPT [2752:190850] :POSTROUTING ACCEPT [1472:88500] -A POSTROUTING -o eth0 -j SNAT --to-source 192.168.2.248 COMMIT # Completed on Mon Aug 22 16:06:21 2016 # Generated by iptables-save v1.4.21 on Mon Aug 22 16:06:21 2016 *filter :INPUT ACCEPT [61997:8558568] :FORWARD ACCEPT [11:836] :OUTPUT ACCEPT [9258:2611777] -A FORWARD -i eth1 -j ACCEPT COMMIT # Completed on Mon Aug 22 16:06:21 2016
I can connect the machines using ssh or ping between them, but I still cannot connect or ping the internet from the client machine (eth0 IP 192.168.200.2). This is the gateway on this:
$ route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.200.1 0.0.0.0 UG 0 0 0 eth0 192.168.200.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
/proc/sys/net/ipv4/ip_forward is 1
Any help are welcome