[bug #19580] ICMP TTL is not decremented

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[bug #19580] ICMP TTL is not decremented

Ashley Duncan

URL:
  <http://savannah.nongnu.org/bugs/?19580>

                 Summary: ICMP TTL is not decremented
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: jifl
            Submitted on: Thursday 04/12/2007 at 02:19
                Category: IPv4
                Severity: 2 - Minor
              Item Group: Faulty Behaviour
                  Status: In Progress
                 Privacy: Public
             Assigned to: jifl
             Open/Closed: Open
         Discussion Lock: Any

    _______________________________________________________

Details:

Someone noted on the lwip-users mailing list that the TTL on ICMP ECHO
REPLIES is not decremented by 1 compared to the ECHO.

I'm pretty sure the attached patch solves this, but I'm not in a position to
test it at the moment.




    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Thursday 04/12/2007 at 02:19  Name: lwip.echo.ttl.patch.txt  Size: 1kB
 By: jifl

<http://savannah.nongnu.org/bugs/download.php?file_id=12467>

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[bug #19580] ICMP TTL is not decremented

Ashley Duncan

Follow-up Comment #1, bug #19580 (project lwip):

I'm not sure that a host have to decrement ttl. I'm agree for a switch or
router. I have experiment on my LAN, and when from my pc, I ping another host
(pc/windows), TTL is the same in the ECHO & ECHO REPLY.  When I ping my
router, the TTL is 128 in ECHO packet, and 64 in ECHO REPLY.

I don't have RFC here, do you have check what is the good behavior?


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[bug #19580] ICMP TTL is not decremented

Ashley Duncan

Follow-up Comment #2, bug #19580 (project lwip):

Hmm, yes. After now researching this, I think the reporter got it the wrong
way round. In fact we should send out an echo reply with the TTL reset back
to default. I guess this is because the return route may be assymetric. The
patch is much simpler now.


(file #12469)
    _______________________________________________________

Additional Item Attachment:

File name: lwip.echo.ttl.2.patch.txt      Size:0 KB


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[bug #19580] ICMP TTL is not decremented

Ashley Duncan

Update of bug #19580 (project lwip):

                  Status:             In Progress => Fixed                  
             Open/Closed:                    Open => Closed                

    _______________________________________________________

Follow-up Comment #3:

I applied the patch.

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