Robert Rozman wrote:
> Hi,
>
> I have trouble setting up above configuration. I've come half way. From
> "linux" computer I can work and see Internet and LAN, I just cannot access
> Internet from LAN (I can access internal LAN computers).
>
> I'd kindly ask for guidance, what is missing in my setup.
>
> Thanks in advance,
>
> regards,
>
> Rob.
>
>
> dcerouter_260:~$ netstat -nr
> Kernel IP routing table
> Destination Gateway Genmask Flags MSS Window irtt
> Iface
> 213.250.19.90 0.0.0.0 255.255.255.255 UH 0 0 0
> ppp0
> 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0
> eth0
> 0.0.0.0 213.250.19.90 0.0.0.0 UG 0 0 0
> ppp0
>
>
> dcerouter_260:~$ ifconfig
> eth0 Link encap:Ethernet HWaddr 00:0E:A6:A7:8B:F4
> inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
> inet6 addr: fe80::20e:a6ff:fea7:8bf4/64 Scope:Link
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:778 errors:0 dropped:0 overruns:0 frame:0
> TX packets:457 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:111611 (108.9 KiB) TX bytes:76826 (75.0 KiB)
> Interrupt:209 Memory:feaf8000-0
>
> eth1 Link encap:Ethernet HWaddr 00:80:5A:28:94:EA
> inet6 addr: fe80::280:5aff:fe28:94ea/64 Scope:Link
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:7121 errors:0 dropped:0 overruns:0 frame:0
> TX packets:9393 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:1089273 (1.0 MiB) TX bytes:5029346 (4.7 MiB)
> Interrupt:193 Base address:0xd000
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> inet6 addr: ::1/128 Scope:Host
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:2674 errors:0 dropped:0 overruns:0 frame:0
> TX packets:2674 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:9503023 (9.0 MiB) TX bytes:9503023 (9.0 MiB)
>
> ppp0 Link encap:Point-to-Point Protocol
> inet addr:193.77.90.224 P-t-P:213.250.19.90 Mask:255.255.255.255
> UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1
> RX packets:23 errors:0 dropped:0 overruns:0 frame:0
> TX packets:73 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:3
> RX bytes:2495 (2.4 KiB) TX bytes:13661 (13.3 KiB)
>
> dcerouter_260:~$
>
>
The internal LAN address you are using is in the private, non-routable
range, which means that any traffic from your local lan that makes it
out onto the Internet will be quietly dropped. This is as it should be.
It is not as simple as setting your Linux box to just route IP packets
from your LAN to the Internet as they will have the rivate IP source
address.
If the Internet connection is working then the next step is to work out
how you want to foward traffic from your local LAN to the Internet.
Basic options are NAT/Masquerade or Proxy.
NAT basically passes all your LAN traffic through to the Internet but
changes the source address to you public Internet address rather than
your private LAN address. Generally done with iptables on Linux. The
advantage to this method is that it will handle pretty much any protocol
(with the possible exception of active ftp connections and other
protcols that assign inbound ports dynamically).
Proxying runs a server on the Linux box which accepts requests then
re-issues them. The benefit is that the request/results can be
manipulated (content/virus scanned etc). Done on a per protocol basis
and used mainly for web access.
If you're a relative beginner you might want to take a look at IPCop
(
http://ipcop.org/) or Smoothwall (
http://smoothwall.org/). Both are
firewall distributions with NAT & Proxying already built in. They
provide a boot iso image to get you up & running (careful - they both
wipe your hard drive as part of their install). The also have a web
based admin screen. If nothing else they will give you a good
understanding of what goes into a firewall type system and how its put
together.
B.
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