[CALUG] More UDP foolishness

[Jason C. Miller]

Yeah...but I would hardly call nmap a common utility (at least, not 
NEARLY as common as something like telnet).  I also mentioned that nmap 
is something that I'm using currently and don't want to have to rely 
since I don't want to have to install it wherever I go. 

                                                  -j


Kelly Price wrote:

>On 4/13/06, Jason C. Miller <jason.c.miller at gmail.com> wrote:
>  
>
>>Oh...almost forgot.  The UDP port in question doesn't reside on your
>>local machine.  Therefore, 'netstat' and other tools like that don't
>>apply.  ;)
>>
>>    
>>
>
>So we're looking at a remotely connected PC.
>
>We need to know where you are connected in relation to that PC, and if
>your laptop has Linux on it.
>
>* If it's on a local network (wire/wireless), nmap.
>* If it's not, but the PC has an direct IP address and so do you, nmap.
>* If ether end is firewalled or behind a NAT router, you're screwed!
>
>
>
>  
>
>>                                                               -j
>>
>>Jason C. Miller wrote:
>>
>>    
>>
>>>Heck....why not!  Here's my random question for the week...  :)
>>>
>>>So, anyway, a lot of troubleshooting and investigation is required with
>>>the stuff that I work on.  For as long as I can remember, I've used
>>>'telnet' as the simplest way to determine whether or not a TCP port is
>>>bound to by an application on a machine.  It's simple, quick, easy, and
>>>comes stock on just about every OS imaginable.  It's a good way to
>>>verify that the 3-way-handshake works on a given port.
>>>
>>>However...
>>>
>>>Can't say it's been quite that simple for the UDP side of the house.
>>>Since UDP is connectionless, the mechanisms for determining if a port is
>>>bound to is a tad different.  Instead of conveniently getting a
>>>(RST,ACK) TCP reply, UDP relies on the receipt of ICMP 'Destination
>>>Unreachable' messages to tell it that the port is not open.  Typically,
>>>I've relied on applications like nmap.  However, I don't really feel
>>>like installing it wherever I go.  I've also written simple progs to do
>>>it, but it's very inconvenient.
>>>
>>>So, the question is....can anybody recommend a COMMON program that you
>>>would find on most operating systems that could be pointed at an
>>>arbitrary UDP port and would tell you the status of that port?  Seems
>>>like it'd be simple, but I can't seem to think of any at the moment.
>>>
>>>                                                      -j
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>>>
>>>
>>>      
>>>
>>--
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>>_______________________________________________
>>Columbia, Maryland Linux User's Group (CALUG) mailing list
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>>
>>    
>>
>
>
>--
>Kelly "STrRedWolf" Price
>http://strredwolf.furrynet.com
>  
>


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