bugGNU GRUB - Bugs: bug #53754, RFC violation: grub2 uses...

 
 

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bug #53754: RFC violation: grub2 uses bootp-gateway IP as router

Submitter:  Alexandra Faust <medic123de>
Submitted:  Wed 25 Apr 2018 06:22:58 PM UTC
   
 
Category:  Network Severity:  Major
Priority:  5 - Normal Item Group:  None
Status:  None Privacy:  Public
Assigned to:  None Originator Name: 
Open/Closed:  Open Release:  Git master
Release:  Reproducibility:  Every Time
Planned Release:  None

Wed 25 Apr 2018 06:27:50 PM UTC, comment #1: 

please close.
it's already fixed in the savannahs git repo (master),
but not on gitlab master

Alexandra Faust <medic123de>
Wed 25 Apr 2018 06:22:58 PM UTC, original submission:  

Hi Guys,
sadly I ran into an issue today.
we have several networks and use Ciscos IOS DHCP-helper to reflect dhcp/bootp requests to our DHCP/BootP server.

Cisco sets the giaddr field to itself, but does not forward regular traffic ( as currently in standby ).

now grub2 kicks in and sets a hostroute to the bootp-server via that router.
sadly, that server is supposed to serve bootfiles also via tftp - and now does timeout.

RFC 1542 states:
A BOOTP client MUST NOT interpret the 'giaddr' field of a BOOTREPLY
   message to be the IP address of an IP router.  A BOOTP client SHOULD
   completely ignore the contents of the 'giaddr' field in BOOTREPLY
   messages.

      DISCUSSION:
         The semantics of the 'giaddr' field were poorly defined.
         Section 7.5 of [1] states:

           "If 'giaddr' (gateway address) is nonzero, then the packets
           should be forwarded there first, in order to get to the
           server."

   In that sentence, "get to" refers to communication from the client to
   the server subsequent to the BOOTP exchange, such as a TFTP session.
   Unfortunately, the 'giaddr' field may contain the address of a BOOTP
   relay agent that is not itself an IP router (according to [1],
   Section 8, fifth paragraph), in which case, it will be useless as a
   first-hop for TFTP packets sent to the server (since, by definition,
   non-routers don't forward datagrams at the IP layer).

https://tools.ietf.org/html/rfc1542#section-3.4

can you please repair it in any way ?
( i tried to overwrite with DHCP static routes - but that didn't work either )

nests
Alex

Alexandra Faust <medic123de>

 

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Attached Files
file #44032:  efi-route.jpg added by medic123de (25KiB - image/jpeg)

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-04-25 medic123de Attached File- Added efi-route.jpg, #44032

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