iptables on DLink DSL-502T Modem/Router
rob0 at gmx.co.uk
Tue Nov 8 03:31:46 CET 2005
On Monday 2005-November-07 19:47, Paul Goodyear wrote:
> Does iptables version v1.2.6a support forwarding from a source IP?
I cannot parse this. Please rephrase (although I think I've answered
your question below.)
> The reason I ask, is I have a DLink DSL-502T modem router, the router
> has linux on and running iptables.
General note about embedded devices: you're limited to the netfilter
drivers that the developer saw fit to include. My Linksys w/Sveasoft
firmware lacks some of the more recent and better toys. (I'm planning
to upgrade to OpenWRT.)
> The webadmin for the router does not allow you to create ip filters,
> port forwarding is there but not filtering.
But apparently you can get to a shell?
> I want to allow access to port 3389 from only 1 internet IP address.
> Should this work? (126.96.36.199 being an example)
> iptables -A INPUT -s 188.8.131.52 -d 192.168.1.2 -p tcp --dport 3389
> -j ACCEPT
Without seeing your rules I can only guess. I have 3 guesses, in the
order they appear on the command line:
1. "-A" : order matters. If an earlier rule does something else with
your MS-RDP traffic from 184.108.40.206 destined to 192.168.1.2, this is
2. "INPUT" : If 192.168.1.2 is not a local IP on the router, this rule
can never be hit. Try "FORWARD".
3. "-d 192.168.1.2" : That's a non-routable RFC 1918 address. You have
to perform DNAT in the nat table prior to this. You implied that this
has been done, but you were not explicit.
Given the topology you described (the rules being on a DSL router) I
would guess number 2 is your problem. Embedded devices are not likely
to be running RDP servers.
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