Re: Filtered Port

[Scott Mayo <sgmayo@mail.bloomfield.k12.mo.us>]

Rob Sterenborg wrote:
> On Tue, January 31, 2006 15:17, Scott Mayo wrote:
> 
>>Rob Sterenborg wrote:
>>
>>>On Tue, January 31, 2006 14:55, Scott Mayo wrote:
>>>
>>>
>>>>I am not sure if this is my iptables or not, but I am not sure where
>>>>else to look or ask.  I am trying to use Remote Desktop on a
>>>>computer.  From inside my network, it works fine, but once I get
>>>>outside, I cannot use it.  I have set my IPTABLES to forward
>>>>anything
>>>>going to port 3389 to the computer that is using Remote Desktop.
>>>>
>>>>The problems seems to be that port 3389 is filtered.  I can find
>>>>nothing in my iptables where I have this port filtered.  Are there
>>>>some generic ports, that IPTABLES filters on it own or something?
>>>>If
>>>>the IPTABLES are not filtering it, what else could be?
>>>
>>>
>>>You allow forwarding to this host but you also need to DNAT these
>>>packets from the internet IP to the IP of your computer.
>>>
>>>$ipt -t nat -A PREROUTING -i <if_inet> -d <ip_inet> \
>>>  -p tcp --dport 3389 -j DNAT --to <ip_controlled_host>
>>>
>>Maybe I used the wrong word when I said 'forward'.  This is the rule
>>that I have in place and it does not seem to be working.  I assumed
>>that it was because the port is filtered, or that is what NMAP tells
>>me when I run it.
>>
>>I still have no idea why port 3389 is shown as being filtered.  I
>>have no rules in my iptables that explicitly filter it.
> 
> 
> In that case you may want to allow forwarding ;-)..
> 
> $ipt -A FORWARD -i <if_inet> -o <if_lan> -d <ip_controlled_host> \
>   -p tcp --dport 3389 -j ACCEPT
> 

This did not let it go through either.  It must not be the iptables 
causing it.  I took everything out of my rules except for the PREROUTING 
rule above and my POSTROUTING rule for SNAT and I am getting the same thing.

I am not sure what else would be blocking this, unless it is the 
upstream ISP.  I don't think it is, but I have sent them an email to 
make sure.  Only thing this machine is used for is to be a filter using 
IPTABLES, Squid and Dansguardian.

Hopefully it has something to do with my ISP, but I really doubt it.

Thanks for the help.

-- 
Scott Mayo
Technology Coordinator
Bloomfield Schools
PH: 573-568-5669
FA: 573-568-4565
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