The kernel rejects IPv6 destination addresses on point-to-point
interfaces if the prefixlen is not 128. Because ifconfig defaults
to prefixlen 64, configuring IPv6 on e.g. gif(4) requires an
explicit prefix length, for instance:
ifconfig gif0 inet6 ADDR1 ADDR2 prefixlen 128
Without prefixlen we get: ifconfig: SIOCAIFADDR: Invalid argument
However, this command works for IPv4:
ifconfig gif0 ADDR1 ADDR2
The netmask isn't forced to 255.255.255.255 by the kernel, though.
Assuming the kernel is correct in enforcing IPv6 prefixlen 128,
for whatever reason, then I suggest we make ifconfig figure out
the required prefixlen by itself so this command works as it
does for IPv4:
ifconfig gif0 inet6 ADDR1 ADDR2
ok?
Index: ifconfig.c
===================================================================
RCS file: /cvs/src/sbin/ifconfig/ifconfig.c,v
retrieving revision 1.344
diff -u -p -r1.344 ifconfig.c
--- ifconfig.c 8 Jun 2017 19:23:39 -0000 1.344
+++ ifconfig.c 24 Jun 2017 04:54:17 -0000
@@ -803,9 +803,13 @@ nextarg:
/*
* Aggregatable address architecture defines all prefixes
* are 64. So, it is convenient to set prefixlen to 64 if
- * it is not specified.
+ * it is not specified. If we are setting a destination
+ * address on a point-to-point interface, 128 is required.
*/
- setifprefixlen("64", 0);
+ if (setipdst && (flags & IFF_POINTOPOINT))
+ setifprefixlen("128", 0);
+ else
+ setifprefixlen("64", 0);
/* in6_getprefix("64", MASK) if MASK is available here... */
}
@@ -1241,6 +1245,7 @@ void
setifdstaddr(const char *addr, int param)
{
setaddr++;
+ setipdst++;
afp->af_getaddr(addr, DSTADDR);
}
