[ale] How to test your public internet connection for open ports

[Ron Frazier]

Hi Michael W.,

I'll have to respond to other messages later.  I've spent the entire 
week typing emails.  I tried the test to your address.  I'll have to try 
the test to mine later.

ron at dell-i1525-1:~$ telnet www.wittsend.com 12345
Trying 130.205.32.81...
telnet: Unable to connect to remote host: Connection refused
ron at dell-i1525-1:~$

The reply took about 1 second.

Actually, I never said I was blocking all ICMP at the router level.  I 
said I was blocking ping, because I have it set that way, and I didn't 
know about the rest.  I also said I was getting green lights on Steve's 
test.  You'd have to watch with a sniffer or examine logs, which my 
router doesn't have, to determine exactly what his test does.

What is interesting, is that I have Firestarter on the PC set to filter 
ICMP.  Perhaps it shouldn't be.  Anyway, if that reply came in by ICMP, 
I don't know how I saw it at all.

Sincerely,

Ron

On 02/11/2011 11:03 AM, Michael H. Warfield wrote:
> Tell you what. Here's another test to try. Telnet to one of my
> machines from behind your NAT device like this:
>
> telnet www.wittsend.com 12345
>
> If it hangs for 30-60 seconds, then you are right and you are dropping
> all ICMP (a bad thing).  If it comes back immediately and says
> "connection refused" then you may think you are dropping all ICMP but
> you are not.  Which probably explains why you don't seem more problems
> than you do.

-- 

(PS - If you email me and don't get a quick response, you might want to
call on the phone.  I get about 300 emails per day from alternate energy
mailing lists and such.  I don't always see new messages very quickly.)

Ron Frazier

770-205-9422 (O)   Leave a message.
linuxdude AT c3energy.com