Date: Thu, 02 Jul 2020 17:24:55 +0000 From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 247700] rtadvd: fails to generate error when iface lacks a link-local address Message-ID: <bug-247700-7501-DEx5GU80jk@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-247700-7501@https.bugs.freebsd.org/bugzilla/> References: <bug-247700-7501@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D247700 --- Comment #3 from Hiroki Sato <hrs@FreeBSD.org> --- It is a valid situation for a unicast communication where a global-scope address is the source address and a link-local-scope address is the destina= tion address though it is not recognized as valid as a Router Advertisement mess= age. Limiting the address selection to the same zone as the destination's is too restrictive. The current implementation prefers a source scope whose scope= is larger than the destination's (c.f. Rule 2, Sec. 5, RFC 6724). Even if the source is smaller than the destination, an address is selected in any way.= =20 However, upon sending a packet, the network stack will discard the packet d= ue to an error "no destination". So in the situation with src=3DGUA/dst=3DLLA, a unicast communication works= and it does not against the specifications. Usually it does not happen because ev= ery interface has at least one LLA configured (c.f. Sec. 2.1, RFC 4291) and the source address selection algorithm always prefers a smaller scope. For an interface with no LLA, I think NDP does not work in various ways bec= ause it (and MLDv2) heavily depends on LLA. It is not limited to Router Advertisement messages. For this reason, FreeBSD configures an EUI-64 LLA = by default. There are some scenarios where only GUAs are configured on an interface, however. To prevent rtadvd(8) from sending invalid packets you reported, I think rtadvd(8) should check if the interface has an LLA or not. I believe running rtadvd(8) on an interface with no LLA is a wrong configuration. Please let me know if I understand your report correctly, and comments abou= t my understanding about the issue you pointed out. If the additional check on rtadvd(8) is sufficient, I will work on it. --=20 You are receiving this mail because: You are on the CC list for the bug.=
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