Hello,
I am troubleshooting a deployment with SCTP and eventually found that
the client has configured the equipment using addresses within the
RFC2544 annex C.2.2 test network (198.18.0.0/15).
Although I think the deployment network may be changed to use another
address space in order to "solve" the issue, the restriction
enforcement on the SCTP kernel driver (implemented by function
sctp_v4_addr_valid -- net/sctp/protocol.c -- in expansion of
IS_IPV4_UNUSABLE_ADDRESS -- include/net/sctp/consntans.h) seems odd to
me, because the address is a valid unicast IPv4 address and should be
acceptable as per RFC4960 clause 8.4:
The receiver of an OOTB packet MUST do the following:
1) If the OOTB packet is to or from a non-unicast address, a
receiver SHOULD silently discard the packet. Otherwise,
The source code states that this restriction came from
draft-stewart-tsvwg-sctp-ipv4, which is true, and the sysctl
net.sctp.addr_scope_policy is documented in ip-sysctl.txt as a switch
for the desired draft behavior, but changing the sysctl value has no
effect because IS_IPV4_UNUSABLE_ADDRESS macro expansion has no
verification of any sysctl configuration nor the sctp_v4_addr_valid.
The draft-stewart-tsvwg-sctp-ipv4 enforcement seems like a bug or I am
missing something?
Best Regards,
Sérgio Surkamp
