URL: <http://savannah.gnu.org/bugs/?53754>
Summary: RFC violation: grub2 uses bootp-gateway IP as router Project: GNU GRUB Submitted by: medic123de Submitted on: 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: Originator Email: Open/Closed: Open Discussion Lock: Any Release: Release: Git master Reproducibility: Every Time Planned Release: None _______________________________________________________ Details: 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 _______________________________________________________ File Attachments: ------------------------------------------------------- Date: Wed 25 Apr 2018 06:22:58 PM UTC Name: efi-route.jpg Size: 25KiB By: medic123de <http://savannah.gnu.org/bugs/download.php?file_id=44032> _______________________________________________________ Reply to this item at: <http://savannah.gnu.org/bugs/?53754> _______________________________________________ Message sent via/by Savannah http://savannah.gnu.org/ _______________________________________________ Bug-grub mailing list Bug-grub@gnu.org https://lists.gnu.org/mailman/listinfo/bug-grub