buglwIP - A Lightweight TCP/IP stack - Bugs: bug #19580, ICMP TTL is not decremented

 
 

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bug #19580: ICMP TTL is not decremented

Submitted by:  Jonathan Larmour <jifl>
Submitted on:  Thu 12 Apr 2007 01:19:12 AM UTC  
 
Category: IPv4Severity: 2 - Minor
Item Group: Faulty BehaviourStatus: Fixed
Privacy: PublicAssigned to: Jonathan Larmour <jifl>
Open/Closed: ClosedPlanned Release: None
lwIP version: None

Thu 12 Apr 2007 06:56:24 PM UTC, comment #3:

I applied the patch.

Jonathan Larmour <jifl>
Project MemberIn charge of this item.
Thu 12 Apr 2007 03:08:21 AM UTC, comment #2:

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)

Jonathan Larmour <jifl>
Project MemberIn charge of this item.
Thu 12 Apr 2007 01:37:33 AM UTC, comment #1:

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?

Frédéric Bernon <fbernon>
Project Member
Thu 12 Apr 2007 01:19:12 AM UTC, original submission:

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.

Jonathan Larmour <jifl>
Project MemberIn charge of this item.

 

Attached Files
file #12469:  lwip.echo.ttl.2.patch.txt added by jifl (897B - text/plain)
file #12467:  lwip.echo.ttl.patch.txt added by jifl (1KiB - text/plain)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by fbernon (Posted a comment)
  • -unavailable- added by jifl (Submitted the item)
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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu 12 Apr 2007 06:56:24 PM UTCjiflStatusIn Progress=>Fixed
      Open/ClosedOpen=>Closed
    Thu 12 Apr 2007 03:08:21 AM UTCjiflAttached File-=>Added lwip.echo.ttl.2.patch.txt, #12469
    Thu 12 Apr 2007 01:19:12 AM UTCjiflAttached File-=>Added lwip.echo.ttl.patch.txt, #12467

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