2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the project nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * $KAME: in6_proto.c,v 1.91 2001/05/27 13:28:35 itojun Exp $
35 * Copyright (c) 1982, 1986, 1993
36 * The Regents of the University of California. All rights reserved.
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. Neither the name of the University nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62 * @(#)in_proto.c 8.1 (Berkeley) 6/10/93
65 #include <sys/cdefs.h>
66 __FBSDID("$FreeBSD$");
69 #include "opt_inet6.h"
70 #include "opt_ipsec.h"
71 #include "opt_ipstealth.h"
73 #include "opt_route.h"
75 #include <sys/param.h>
76 #include <sys/socket.h>
77 #include <sys/socketvar.h>
79 #include <sys/protosw.h>
81 #include <sys/kernel.h>
82 #include <sys/malloc.h>
83 #include <sys/domain.h>
85 #include <sys/systm.h>
86 #include <sys/sysctl.h>
89 #include <net/if_var.h>
90 #include <netinet/in.h>
91 #include <netinet/ip6.h>
92 #include <netinet6/in6_var.h>
93 #include <netinet6/ip6_var.h>
94 #include <netinet/icmp6.h>
95 #include <netinet6/nd6.h>
96 #include <netinet6/raw_ip6.h>
98 /* netinet6/raw_ip6.c */
99 extern struct protosw rip6_protosw;
100 /* netinet6/udp6_usrreq.c */
101 extern struct protosw udp6_protosw, udplite6_protosw;
102 /* netinet/tcp_usrreq.c */
103 extern struct protosw tcp6_protosw;
104 /* netinet/sctp6_usrreq.c */
105 extern struct protosw sctp6_seqpacket_protosw, sctp6_stream_protosw;
108 * TCP/IP protocol family: IP6, ICMP6, UDP, TCP.
110 FEATURE(inet6, "Internet Protocol version 6");
112 struct domain inet6domain = {
113 .dom_family = AF_INET6,
114 .dom_name = "internet6",
115 .dom_rtattach = in6_inithead,
117 .dom_rtdetach = in6_detachhead,
119 .dom_ifattach = in6_domifattach,
120 .dom_ifdetach = in6_domifdetach,
121 .dom_ifmtu = in6_domifmtu,
127 &sctp6_seqpacket_protosw,
128 &sctp6_stream_protosw,
134 /* Spacer 8 times for loadable protocols. XXXGL: why 8? */
135 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
142 * Internet configuration info
144 #ifndef IPV6FORWARDING
146 #define IPV6FORWARDING 1 /* forward IP6 packets not for us */
148 #define IPV6FORWARDING 0 /* don't forward IP6 packets not for us */
149 #endif /* GATEWAY6 */
150 #endif /* !IPV6FORWARDING */
152 #ifndef IPV6_SENDREDIRECTS
153 #define IPV6_SENDREDIRECTS 1
156 VNET_DEFINE(int, ip6_forwarding) = IPV6FORWARDING; /* act as router? */
157 VNET_DEFINE(int, ip6_sendredirects) = IPV6_SENDREDIRECTS;
158 VNET_DEFINE(int, ip6_defhlim) = IPV6_DEFHLIM;
159 VNET_DEFINE(int, ip6_defmcasthlim) = IPV6_DEFAULT_MULTICAST_HOPS;
160 VNET_DEFINE(int, ip6_accept_rtadv) = 0;
161 VNET_DEFINE(int, ip6_no_radr) = 0;
162 VNET_DEFINE(int, ip6_norbit_raif) = 0;
163 VNET_DEFINE(int, ip6_rfc6204w3) = 0;
164 VNET_DEFINE(int, ip6_hdrnestlimit) = 15;/* How many header options will we
166 VNET_DEFINE(int, ip6_dad_count) = 1; /* DupAddrDetectionTransmits */
167 VNET_DEFINE(int, ip6_auto_flowlabel) = 1;
168 VNET_DEFINE(int, ip6_use_deprecated) = 1;/* allow deprecated addr
170 VNET_DEFINE(int, ip6_rr_prune) = 5; /* router renumbering prefix
171 * walk list every 5 sec. */
172 VNET_DEFINE(int, ip6_mcast_pmtu) = 0; /* enable pMTU discovery for multicast? */
173 VNET_DEFINE(int, ip6_v6only) = 1;
176 VNET_DEFINE(int, ip6stealth) = 0;
178 VNET_DEFINE(int, nd6_onlink_ns_rfc4861) = 0;/* allow 'on-link' nd6 NS
180 VNET_DEFINE(bool, ip6_log_cannot_forward) = 1;
184 * BSDI4 defines these variables in in_proto.c...
185 * XXX: what if we don't define INET? Should we define pmtu6_expire
186 * or so? (jinmei@kame.net 19990310)
188 VNET_DEFINE(int, pmtu_expire) = 60*10;
189 VNET_DEFINE(int, pmtu_probe) = 60*2;
191 /* ICMPV6 parameters */
192 VNET_DEFINE(int, icmp6_rediraccept) = 1;/* accept and process redirects */
193 VNET_DEFINE(int, icmp6_redirtimeout) = 10 * 60; /* 10 minutes */
194 VNET_DEFINE(int, icmp6errppslim) = 100; /* 100pps */
195 /* control how to respond to NI queries */
196 VNET_DEFINE(int, icmp6_nodeinfo) =
197 (ICMP6_NODEINFO_FQDNOK|ICMP6_NODEINFO_NODEADDROK);
198 VNET_DEFINE(int, icmp6_nodeinfo_oldmcprefix) = 1;
200 VNET_DEFINE_STATIC(int, ip6_log_interval) = 5;
201 VNET_DEFINE_STATIC(int, ip6_log_count) = 0;
202 VNET_DEFINE_STATIC(struct timeval, ip6_log_last) = { 0 };
204 #define V_ip6_log_interval VNET(ip6_log_interval)
205 #define V_ip6_log_count VNET(ip6_log_count)
206 #define V_ip6_log_last VNET(ip6_log_last)
209 * sysctl related items.
211 SYSCTL_NODE(_net, PF_INET6, inet6, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
215 SYSCTL_NODE(_net_inet6, IPPROTO_IPV6, ip6, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
217 SYSCTL_NODE(_net_inet6, IPPROTO_ICMPV6, icmp6, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
219 SYSCTL_NODE(_net_inet6, IPPROTO_UDP, udp6, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
221 SYSCTL_NODE(_net_inet6, IPPROTO_TCP, tcp6, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
223 #if defined(SCTP) || defined(SCTP_SUPPORT)
224 SYSCTL_NODE(_net_inet6, IPPROTO_SCTP, sctp6, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
227 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
228 SYSCTL_NODE(_net_inet6, IPPROTO_ESP, ipsec6, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
234 sysctl_ip6_temppltime(SYSCTL_HANDLER_ARGS)
238 val = V_ip6_temp_preferred_lifetime;
239 error = sysctl_handle_int(oidp, &val, 0, req);
240 if (error != 0 || !req->newptr)
242 if (val < V_ip6_desync_factor + V_ip6_temp_regen_advance)
244 V_ip6_temp_preferred_lifetime = val;
249 sysctl_ip6_tempvltime(SYSCTL_HANDLER_ARGS)
253 val = V_ip6_temp_valid_lifetime;
254 error = sysctl_handle_int(oidp, &val, 0, req);
255 if (error != 0 || !req->newptr)
257 if (val < V_ip6_temp_preferred_lifetime)
259 V_ip6_temp_valid_lifetime = val;
264 ip6_log_ratelimit(void)
267 return (ppsratecheck(&V_ip6_log_last, &V_ip6_log_count,
268 V_ip6_log_interval));
271 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_FORWARDING, forwarding,
272 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_forwarding), 0,
273 "Enable forwarding of IPv6 packets between interfaces");
274 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_SENDREDIRECTS, redirect,
275 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_sendredirects), 0,
276 "Send ICMPv6 redirects for unforwardable IPv6 packets");
277 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_DEFHLIM, hlim,
278 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_defhlim), 0,
279 "Default hop limit to use for outgoing IPv6 packets");
280 SYSCTL_VNET_PCPUSTAT(_net_inet6_ip6, IPV6CTL_STATS, stats, struct ip6stat,
282 "IP6 statistics (struct ip6stat, netinet6/ip6_var.h)");
283 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_ACCEPT_RTADV, accept_rtadv,
284 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_accept_rtadv), 0,
285 "Default value of per-interface flag for accepting ICMPv6 RA messages");
286 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_NO_RADR, no_radr,
287 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_no_radr), 0,
288 "Default value of per-interface flag to control whether routers "
289 "sending ICMPv6 RA messages on that interface are added into the "
290 "default router list");
291 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_NORBIT_RAIF, norbit_raif,
292 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_norbit_raif), 0,
293 "Always set clear the R flag in ICMPv6 NA messages when accepting RA "
295 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RFC6204W3, rfc6204w3,
296 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_rfc6204w3), 0,
297 "Accept the default router list from ICMPv6 RA messages even "
298 "when packet forwarding is enabled");
299 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_LOG_INTERVAL, log_interval,
300 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_log_interval), 0,
301 "Frequency in seconds at which to log IPv6 forwarding errors");
302 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_HDRNESTLIMIT, hdrnestlimit,
303 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_hdrnestlimit), 0,
304 "Default maximum number of IPv6 extension headers permitted on "
305 "incoming IPv6 packets, 0 for no artificial limit");
306 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_DAD_COUNT, dad_count,
307 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_dad_count), 0,
308 "Number of ICMPv6 NS messages sent during duplicate address detection");
309 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_AUTO_FLOWLABEL, auto_flowlabel,
310 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_auto_flowlabel), 0,
311 "Provide an IPv6 flowlabel in outbound packets");
312 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_DEFMCASTHLIM, defmcasthlim,
313 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_defmcasthlim), 0,
314 "Default hop limit for IPv6 multicast packets originating from this "
316 SYSCTL_STRING(_net_inet6_ip6, IPV6CTL_KAME_VERSION, kame_version,
317 CTLFLAG_RD, __KAME_VERSION, 0,
318 "KAME version string");
319 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_USE_DEPRECATED, use_deprecated,
320 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_use_deprecated), 0,
321 "Allow the use of addresses whose preferred lifetimes have expired");
322 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RR_PRUNE, rr_prune,
323 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_rr_prune), 0,
324 ""); /* XXX unused */
325 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_USETEMPADDR, use_tempaddr,
326 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_use_tempaddr), 0,
327 "Create RFC3041 temporary addresses for autoconfigured addresses");
328 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_TEMPPLTIME, temppltime,
329 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
330 NULL, 0, sysctl_ip6_temppltime, "I",
331 "Maximum preferred lifetime for temporary addresses");
332 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_TEMPVLTIME, tempvltime,
333 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
334 NULL, 0, sysctl_ip6_tempvltime, "I",
335 "Maximum valid lifetime for temporary addresses");
336 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_V6ONLY, v6only,
337 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_v6only), 0,
338 "Restrict AF_INET6 sockets to IPv6 addresses only");
339 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_AUTO_LINKLOCAL, auto_linklocal,
340 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_auto_linklocal), 0,
341 "Default value of per-interface flag for automatically adding an IPv6 "
342 "link-local address to interfaces when attached");
343 SYSCTL_VNET_PCPUSTAT(_net_inet6_ip6, IPV6CTL_RIP6STATS, rip6stats,
344 struct rip6stat, rip6stat,
345 "Raw IP6 statistics (struct rip6stat, netinet6/raw_ip6.h)");
346 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_PREFER_TEMPADDR, prefer_tempaddr,
347 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_prefer_tempaddr), 0,
348 "Prefer RFC3041 temporary addresses in source address selection");
349 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_USE_DEFAULTZONE, use_defaultzone,
350 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_use_defzone), 0,
351 "Use the default scope zone when none is specified");
352 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MCAST_PMTU, mcast_pmtu,
353 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_mcast_pmtu), 0,
354 "Enable path MTU discovery for multicast packets");
356 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_STEALTH, stealth, CTLFLAG_VNET | CTLFLAG_RW,
357 &VNET_NAME(ip6stealth), 0,
358 "Forward IPv6 packets without decrementing their TTL");
360 SYSCTL_BOOL(_net_inet6_ip6, OID_AUTO,
361 log_cannot_forward, CTLFLAG_VNET | CTLFLAG_RW,
362 &VNET_NAME(ip6_log_cannot_forward), 1,
363 "Log packets that cannot be forwarded");
365 /* net.inet6.icmp6 */
366 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_REDIRACCEPT, rediraccept,
367 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6_rediraccept), 0,
368 "Accept ICMPv6 redirect messages");
369 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_REDIRTIMEOUT, redirtimeout,
370 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6_redirtimeout), 0,
371 "Delay in seconds before expiring redirect route");
372 SYSCTL_VNET_PCPUSTAT(_net_inet6_icmp6, ICMPV6CTL_STATS, stats,
373 struct icmp6stat, icmp6stat,
374 "ICMPv6 statistics (struct icmp6stat, netinet/icmp6.h)");
375 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_PRUNE, nd6_prune,
376 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_prune), 0,
377 "Frequency in seconds of checks for expired prefixes and routers");
378 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_DELAY, nd6_delay,
379 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_delay), 0,
380 "Delay in seconds before probing for reachability");
381 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_UMAXTRIES, nd6_umaxtries,
382 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_umaxtries), 0,
383 "Number of ICMPv6 NS messages sent during reachability detection");
384 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_MMAXTRIES, nd6_mmaxtries,
385 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_mmaxtries), 0,
386 "Number of ICMPv6 NS messages sent during address resolution");
387 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_USELOOPBACK, nd6_useloopback,
388 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_useloopback), 0,
389 "Create a loopback route when configuring an IPv6 address");
390 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_NODEINFO, nodeinfo,
391 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6_nodeinfo), 0,
392 "Mask of enabled RFC4620 node information query types");
393 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_NODEINFO_OLDMCPREFIX,
394 nodeinfo_oldmcprefix, CTLFLAG_VNET | CTLFLAG_RW,
395 &VNET_NAME(icmp6_nodeinfo_oldmcprefix), 0,
396 "Join old IPv6 NI group address in draft-ietf-ipngwg-icmp-name-lookup "
397 "for compatibility with KAME implementation");
398 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ERRPPSLIMIT, errppslimit,
399 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmp6errppslim), 0,
400 "Maximum number of ICMPv6 error messages per second");
401 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_MAXNUDHINT, nd6_maxnudhint,
402 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_maxnudhint), 0,
403 ""); /* XXX unused */
404 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_DEBUG, nd6_debug,
405 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nd6_debug), 0,
406 "Log NDP debug messages");
407 SYSCTL_INT(_net_inet6_icmp6, ICMPV6CTL_ND6_ONLINKNSRFC4861,
408 nd6_onlink_ns_rfc4861, CTLFLAG_VNET | CTLFLAG_RW,
409 &VNET_NAME(nd6_onlink_ns_rfc4861), 0,
410 "Accept 'on-link' ICMPv6 NS messages in compliance with RFC 4861");
412 SYSCTL_INT(_net_inet6_icmp6, OID_AUTO,
413 nd6_ignore_ipv6_only_ra, CTLFLAG_VNET | CTLFLAG_RW,
414 &VNET_NAME(nd6_ignore_ipv6_only_ra), 0,
415 "Ignore the 'IPv6-Only flag' in RA messages in compliance with "
416 "draft-ietf-6man-ipv6only-flag");