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--Apple-Mail=_34D971FD-B2DA-4F26-B33F-055D8F4B9B9F Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii <html><head><meta http-equiv=3D"content-type" content=3D"text/html; = charset=3Dus-ascii"></head><body style=3D"overflow-wrap: break-word; = -webkit-nbsp-mode: space; line-break: after-white-space;"><br = id=3D"lineBreakAtBeginningOfMessage"><div><br><blockquote = type=3D"cite"><div>On 29 Apr 2024, at 03:09, Rodney W. Grimes = <freebsd-rwg@gndrsh.dnsmgr.net> wrote:</div><br = class=3D"Apple-interchange-newline"><div><meta = charset=3D"UTF-8"><blockquote type=3D"cite" style=3D"font-family: = Helvetica; font-size: 12px; font-style: normal; font-variant-caps: = normal; font-weight: 400; letter-spacing: normal; orphans: auto; = text-align: start; text-indent: 0px; text-transform: none; white-space: = normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; = text-decoration: none;">Would anyone know if there is something special = with tunnel devices and multicast ?<span = class=3D"Apple-converted-space"> </span><br><br>I?ve got some code = that happily processes multicast packets on a normal interface; but = appears not to do this on a tunnel interface. Tun0 shows multicast = enabled:<br><span class=3D"Apple-tab-span" style=3D"white-space: pre;"> = </span><br><span class=3D"Apple-tab-span" style=3D"white-space: pre;"> = </span>tun0: flags=3D8043<UP,BROADCAST,RUNNING,MULTICAST> metric 0 = mtu 1500<br><br>Tcpdump on that interface gives the expected thing (here = with mDNS):<br><br><span class=3D"Apple-tab-span" style=3D"white-space: = pre;"> </span>tcpdump -n -i tun0 port 5353<br><span = class=3D"Apple-tab-span" style=3D"white-space: pre;"> </span>listening = on tun0, link-type NULL (BSD loopback), capture size 262144 = bytes<br><span class=3D"Apple-tab-span" style=3D"white-space: pre;"> = </span>19:26:03.976259 IP 10.31.0.6.5353 > 224.0.0.251.5353: 0 PTR = (QM)? _raop._tcp.local. (34)<br><br>And code, with a simple = IP_ADD_MEMBERSHIP of the MC group on the IP of the local interface = below works on a normal interface (e.g. igb0/10.0.0.1/24).<span = class=3D"Apple-converted-space"> </span><br><br><span = class=3D"Apple-tab-span" style=3D"white-space: pre;"> = </span>./listener 10.0.0.1 224.0.0.251 5353<br></blockquote><br = style=3D"caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: = 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; = letter-spacing: normal; text-align: start; text-indent: 0px; = text-transform: none; white-space: normal; word-spacing: 0px; = -webkit-text-stroke-width: 0px; text-decoration: none;"><span = style=3D"caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: = 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; = letter-spacing: normal; text-align: start; text-indent: 0px; = text-transform: none; white-space: normal; word-spacing: 0px; = -webkit-text-stroke-width: 0px; text-decoration: none; float: none; = display: inline !important;">Is 10.0.0.1 the IP address of tun0, or is = it the address of some other interface?</span><br style=3D"caret-color: = rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: = normal; font-variant-caps: normal; font-weight: 400; letter-spacing: = normal; text-align: start; text-indent: 0px; text-transform: none; = white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; = text-decoration: none;"></div></blockquote><div><blockquote = type=3D"cite">I suspect that the IP address of the tun0 interface is = 10.31.0.6 from your tcpdump above.<br></blockquote><br></div>That is = correct 10.0.0.1/8. 10.31.0.6 is another machine at the other end of the = tunnel broadcasting.</div><div><br></div><div><blockquote = type=3D"cite"><div><span style=3D"caret-color: rgb(0, 0, 0); = font-family: Helvetica; font-size: 12px; font-style: normal; = font-variant-caps: normal; font-weight: 400; letter-spacing: normal; = text-align: start; text-indent: 0px; text-transform: none; white-space: = normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; = text-decoration: none; float: none; display: inline !important;">IIRC = you have to join multicast group on all interfaces you expect to receive = mustcast packets on.</span><br style=3D"caret-color: rgb(0, 0, 0); = font-family: Helvetica; font-size: 12px; font-style: normal; = font-variant-caps: normal; font-weight: 400; letter-spacing: normal; = text-align: start; text-indent: 0px; text-transform: none; white-space: = normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; = text-decoration: none;"><br style=3D"caret-color: rgb(0, 0, 0); = font-family: Helvetica; font-size: 12px; font-style: normal; = font-variant-caps: normal; font-weight: 400; letter-spacing: normal; = text-align: start; text-indent: 0px; text-transform: none; white-space: = normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; = text-decoration: none;"><blockquote type=3D"cite" style=3D"font-family: = Helvetica; font-size: 12px; font-style: normal; font-variant-caps: = normal; font-weight: 400; letter-spacing: normal; orphans: auto; = text-align: start; text-indent: 0px; text-transform: none; white-space: = normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; = text-decoration: none;"><span class=3D"Apple-tab-span" = style=3D"white-space: pre;"> </span>Received packet, len=3D128<br><span= class=3D"Apple-tab-span" style=3D"white-space: pre;"> = </span>etc<br><br>But yields no output if ran against above tun0 = interface (while tcpdump on same is fine). Does that ring a bell with = anyone ?<br><br>Dw<br><br><br>int main(int argc, char = *argv[])<br>{<br> struct sockaddr_in = addr;<br> struct ip_mreq mreq;<br><br><span = class=3D"Apple-tab-span" style=3D"white-space: pre;"> </span>// skip = error trapping command line arguments<br><br> char* ip = =3D argv[1];<span = class=3D"Apple-converted-space"> </span><br> char* = group =3D argv[2];<span = class=3D"Apple-converted-space"> </span><br> int = port =3D atoi(argv[3]); // 0 if error, which is an invalid = port<br><br> memset(&addr, 0, = sizeof(addr));<br> addr.sin_family =3D = AF_INET;<br> addr.sin_addr.s_addr =3D = htonl(INADDR_ANY);<br> addr.sin_port =3D = htons(port);<br><br> mreq.imr_interface.s_addr =3D = inet_addr(ip);<span = class=3D"Apple-converted-space"> </span><br> mreq.im= r_multiaddr.s_addr =3D inet_addr(group);<br><br><span = class=3D"Apple-tab-span" style=3D"white-space: pre;"> </span>// skip = error trapping on inet_addr<br><br> int fd =3D = socket(AF_INET, SOCK_DGRAM, 0);<br><span class=3D"Apple-tab-span" = style=3D"white-space: pre;"> </span>// skip error trapping = socket<br><br> if (bind(fd, (struct sockaddr*) = &addr, sizeof(addr)) < 0) {<br><span class=3D"Apple-tab-span" = style=3D"white-space: pre;"> </span>// skip error = trapping<br><br> if (setsockopt(fd, IPPROTO_IP, = IP_ADD_MEMBERSHIP, (char*) &mreq, sizeof(mreq)) < 0 ){<br><span = class=3D"Apple-tab-span" style=3D"white-space: pre;"> </span>// skip = error trapping argumetns<br><br> while (1) {<br><span = class=3D"Apple-tab-span" style=3D"white-space: pre;"> = </span>..<br> int nbytes =3D = recvfrom(fd,msgbuf,MSGBUFSIZE,0,(struct sockaddr *) = &addr,&addrlen);<br> if = (nbytes < 0) = {<br> per= ror("recvfrom");<br> = return = 1;<br> }<br><span = class=3D"Apple-tab-span" style=3D"white-space: pre;"> = </span>printf(?Received packet, len=3D%d\n", = nbytes);<br> }<br><br></blockquote></div></blockquo= te></div><br></body></html>= --Apple-Mail=_34D971FD-B2DA-4F26-B33F-055D8F4B9B9F--
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