check_real: what does it really do? and is it enough?
Magnus Glantz
magnus at hacka.net
Fri Apr 11 20:32:45 CEST 2003
I'm trying to figure out what exactly the check_real plugin checks.. using the -url option, does it actually start a stream with the server? Or does it only check if the .rm file is there and reachable? If check_real only checks for a description of the file, is it enough to say that the service is OK?
I dumped the conversation (tcpdump -X) while doing:
./check_real -H host -u /url/file.rm
I'm not 100% sure what happens..
Though.. I've been able to understand some stuff..
( I've had some help interpeting the packets from the RTSP RFC.
http://www.freesoft.org/CIE/RFC/bynum.cgi?2326 )
16:59:50.696763 netsaint.37062 > streaming-server.rtsp: P 1:36(35) ack 1 win 5840 <nop,nop,timestamp 293933168 2773241811> (DF)
0x0000 4500 0057 a274 4000 4006 4bd5 c2ec e2e9 E..W.t at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b21d 7381 de14 .C.=...*P...s...
0x0020 8018 16d0 04f6 0000 0101 080a 1185 1070 ...............p
0x0030 a54c 4fd3 4f50 5449 4f4e 5320 7274 7370 .LO.OPTIONS.rtsp
0x0040 3a2f 2f28 6e75 6c6c 293a 3535 3420 5254 ://(null):554.RT
0x0050 5350 SP
Above.. the Nagios server asks the real server for the available methods. (PLAY PAUSE etc..)
16:59:50.766763 netsaint.37062 > streaming-server.rtsp: P 45:102(57) ack 270 win 6432 <nop,nop,timestamp 293933175 2773241817> (DF)
0x0000 4500 006d a277 4000 4006 4bbc c2ec e2e9 E..m.w at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b249 7381 df21 .C.=...*P..Is..!
0x0020 8018 1920 0dac 0000 0101 080a 1185 1077 ...............w
0x0030 a54c 4fd9 4445 5343 5249 4245 2072 7473 .LO.DESCRIBE.rts
0x0040 703a 2f2f 286e 756c 6c29 3a35 3534 2f74 p://(null):554/t
0x0050 692f i/
Above.. check_real asks the real-server of a description of the file.
16:59:51.276763 streaming-server.rtsp > netsaint.37062: P 4614:5232(618) ack 111 win 33304 <nop,nop,timestamp 2773241837 293933187> (DF)
0x0000 4500 029e 1e46 4000 3906 d4bc c343 e33d E....F at .9....C.=
0x0010 c2ec e2e9 022a 90c6 7381 f019 50ff b28b .....*..s...P...
0x0020 8018 8218 a8af 0000 0101 080a a54c 4fed .............LO.
0x0030 1185 1083 7468 203c 2032 3630 3030 292c ....th.<.26000),
0x0040 4176 6572 6167 6542 616e 6477 6964 7468 AverageBandwidth
0x0050 3d31 =1
After this Nagios (the Netsaint host) sends win 0, and finilizes the connection.
Now, the question is.. what did the check_real plugin test? That you can get an description of a file on the server?
The author of the plug-in writes in his source code (check_real.c).
----------------snip-------------
/* Part II - Check stream exists and is ok */
if ((result == STATE_OK) && (server_url != NULL)) {
/* Part I - Server Check */
/* send the OPTIONS request */
sprintf (buffer, "DESCRIBE rtsp://%s:%d%s RTSP/1.0\n", host_name,
server_port, server_url);
result = send (sd, buffer, strlen (buffer), 0);
/* send the header sync */
sprintf (buffer, "CSeq: 2\n");
result = send (sd, buffer, strlen (buffer), 0);
/* send a newline so the server knows we're done with the request */
sprintf (buffer, "\n");
result = send (sd, buffer, strlen (buffer), 0);
----------------snip-------------
DESCRIBE seems to be the last actuall command that the check_real plugin send to the server.
But I could be wrong.. please check for yourselfs.
An actual stream is from what I can tell, not initialized..
Though, if the server give an description of the file (the description comes from the file itself) I guess a stream should
be able to be initialized.. but.. then again, I'm no TCP/IP or RTSP expert.
Full dump of "check_real -H hostname -u /url/file.rm" below..
Hope you can shed some light upon this..
Cheers,
//Magnus Glantz
16:59:50.676763 netsaint.37062 > streaming-server.rtsp.rtsp: S 1358934556:1358934556(0) win 5840 <mss 1460,sackOK,timestamp 293933166 0,nop,wscale 0> (DF)
0x0000 4500 003c a272 4000 4006 4bf2 c2ec e2e9 E..<.r at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b21c 0000 0000 .C.=...*P.......
0x0020 a002 16d0 2ce0 0000 0204 05b4 0402 080a ....,...........
0x0030 1185 106e 0000 0000 0103 0300 ...n........
16:59:50.696763 streaming-server.rtsp > netsaint.37062: S 1937890835:1937890835(0) ack 1358934557 win 33304 <nop,nop,timestamp 2773241811 293933166,nop,wscale 0,nop,nop,sackOK,mss 1460> (DF)
0x0000 4500 0040 1e3f 4000 3906 d721 c343 e33d E.. at .?@.9..!.C.=
0x0010 c2ec e2e9 022a 90c6 7381 de13 50ff b21d .....*..s...P...
0x0020 b012 8218 68cb 0000 0101 080a a54c 4fd3 ....h........LO.
0x0030 1185 106e 0103 0300 0101 0402 0204 05b4 ...n............
16:59:50.696763 netsaint.37062 > streaming-server.rtsp: . ack 1 win 5840 <nop,nop,timestamp 293933168 2773241811> (DF)
0x0000 4500 0034 a273 4000 4006 4bf9 c2ec e2e9 E..4.s at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b21d 7381 de14 .C.=...*P...s...
0x0020 8010 16d0 14dd 0000 0101 080a 1185 1070 ...............p
0x0030 a54c 4fd3 .LO.
16:59:50.696763 netsaint.37062 > streaming-server.rtsp: P 1:36(35) ack 1 win 5840 <nop,nop,timestamp 293933168 2773241811> (DF)
0x0000 4500 0057 a274 4000 4006 4bd5 c2ec e2e9 E..W.t at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b21d 7381 de14 .C.=...*P...s...
0x0020 8018 16d0 04f6 0000 0101 080a 1185 1070 ...............p
0x0030 a54c 4fd3 4f50 5449 4f4e 5320 7274 7370 .LO.OPTIONS.rtsp
0x0040 3a2f 2f28 6e75 6c6c 293a 3535 3420 5254 ://(null):554.RT
0x0050 5350 SP
16:59:50.726763 streaming-server.rtsp > netsaint.37062: . ack 36 win 33304 <nop,nop,timestamp 2773241814 293933168> (DF)
0x0000 4500 0034 1e40 4000 3906 d72c c343 e33d E..4.@@.9..,.C.=
0x0010 c2ec e2e9 022a 90c6 7381 de14 50ff b240 .....*..s...P..@
0x0020 8010 8218 a96e 0000 0101 080a a54c 4fd6 .....n.......LO.
0x0030 1185 1070 ...p
16:59:50.726763 netsaint.37062 > streaming-server.rtsp: P 36:45(9) ack 1 win 5840 <nop,nop,timestamp 293933171 2773241814> (DF)
0x0000 4500 003d a275 4000 4006 4bee c2ec e2e9 E..=.u at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b240 7381 de14 .C.=...*P.. at s...
0x0020 8018 16d0 f6b3 0000 0101 080a 1185 1073 ...............s
0x0030 a54c 4fd6 4353 6571 3a20 310a 0a .LO.CSeq:.1..
16:59:50.766763 streaming-server.rtsp > netsaint.37062: P 1:270(269) ack 45 win 33304 <nop,nop,timestamp 2773241817 293933171> (DF)
0x0000 4500 0141 1e41 4000 3906 d61e c343 e33d E..A.A at .9....C.=
0x0010 c2ec e2e9 022a 90c6 7381 de14 50ff b249 .....*..s...P..I
0x0020 8018 8218 1a2f 0000 0101 080a a54c 4fd9 ...../.......LO.
0x0030 1185 1073 5254 5350 2f31 2e30 2032 3030 ...sRTSP/1.0.200
0x0040 204f 4b0d 0a43 5365 713a 2031 0d0a 4461 .OK..CSeq:.1..Da
0x0050 7465 te
16:59:50.766763 netsaint.37062 > streaming-server.rtsp: . ack 270 win 6432 <nop,nop,timestamp 293933175 2773241817> (DF)
0x0000 4500 0034 a276 4000 4006 4bf6 c2ec e2e9 E..4.v at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b249 7381 df21 .C.=...*P..Is..!
0x0020 8010 1920 1147 0000 0101 080a 1185 1077 .....G.........w
0x0030 a54c 4fd9 .LO.
16:59:50.766763 netsaint.37062 > streaming-server.rtsp: P 45:102(57) ack 270 win 6432 <nop,nop,timestamp 293933175 2773241817> (DF)
0x0000 4500 006d a277 4000 4006 4bbc c2ec e2e9 E..m.w at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b249 7381 df21 .C.=...*P..Is..!
0x0020 8018 1920 0dac 0000 0101 080a 1185 1077 ...............w
0x0030 a54c 4fd9 4445 5343 5249 4245 2072 7473 .LO.DESCRIBE.rts
0x0040 703a 2f2f 286e 756c 6c29 3a35 3534 2f74 p://(null):554/t
0x0050 692f i/
16:59:50.886763 streaming-server.rtsp > netsaint.37062: . ack 102 win 33304 <nop,nop,timestamp 2773241831 293933175> (DF)
0x0000 4500 0034 1e42 4000 3906 d72a c343 e33d E..4.B at .9..*.C.=
0x0010 c2ec e2e9 022a 90c6 7381 df21 50ff b282 .....*..s..!P...
0x0020 8010 8218 a807 0000 0101 080a a54c 4fe7 .............LO.
0x0030 1185 1077 ...w
16:59:50.886763 netsaint.37062 > streaming-server.rtsp: P 102:111(9) ack 270 win 6432 <nop,nop,timestamp 293933187 2773241831> (DF)
0x0000 4500 003d a278 4000 4006 4beb c2ec e2e9 E..=.x at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b282 7381 df21 .C.=...*P...s..!
0x0020 8018 1920 f1f3 0000 0101 080a 1185 1083 ................
0x0030 a54c 4fe7 4353 6571 3a20 320a 0a .LO.CSeq:.2..
16:59:51.046763 streaming-server.rtsp > netsaint.37062: . 270:1718(1448) ack 111 win 33304 <nop,nop,timestamp 2773241837 293933187> (DF)
0x0000 4500 05dc 1e43 4000 3906 d181 c343 e33d E....C at .9....C.=
0x0010 c2ec e2e9 022a 90c6 7381 df21 50ff b28b .....*..s..!P...
0x0020 8010 8218 3fd8 0000 0101 080a a54c 4fed ....?........LO.
0x0030 1185 1083 5254 5350 2f31 2e30 2032 3030 ....RTSP/1.0.200
0x0040 204f 4b0d 0a43 5365 713a 2032 0d0a 4461 .OK..CSeq:.2..Da
0x0050 7465 te
16:59:51.046763 netsaint.37062 > streaming-server.rtsp: R 111:111(0) ack 1718 win 8688 <nop,nop,timestamp 293933203 2773241837> (DF)
0x0000 4500 0034 a279 4000 4006 4bf3 c2ec e2e9 E..4.y at .@.K.....
0x0010 c343 e33d 90c6 022a 50ff b28b 7381 e4c9 .C.=...*P...s...
0x0020 8014 21f0 0259 0000 0101 080a 1185 1093 ..!..Y..........
0x0030 a54c 4fed .LO.
16:59:51.136763 streaming-server.rtsp > netsaint.37062: P 1718:3166(1448) ack 111 win 33304 <nop,nop,timestamp 2773241837 293933187> (DF)
0x0000 4500 05dc 1e44 4000 3906 d180 c343 e33d E....D at .9....C.=
0x0010 c2ec e2e9 022a 90c6 7381 e4c9 50ff b28b .....*..s...P...
0x0020 8018 8218 6d86 0000 0101 080a a54c 4fed ....m........LO.
0x0030 1185 1083 300a 613d 5374 6172 7454 696d ....0.a=StartTim
0x0040 653a 696e 7465 6765 723b 300a 613d 4176 e:integer;0.a=Av
0x0050 6742 gB
16:59:51.136763 netsaint.37062 > streaming-server.rtsp: R 1358934667:1358934667(0) win 0 (DF)
0x0000 4500 0028 0000 4000 ff06 2f78 c2ec e2e9 E..(.. at .../x....
0x0010 c343 e33d 90c6 022a 50ff b28b 0000 0000 .C.=...*P.......
0x0020 5004 0000 cd0d 0000 P.......
16:59:51.236763 streaming-server.rtsp > netsaint.37062: . 3166:4614(1448) ack 111 win 33304 <nop,nop,timestamp 2773241837 293933187> (DF)
0x0000 4500 05dc 1e45 4000 3906 d17f c343 e33d E....E at .9....C.=
0x0010 c2ec e2e9 022a 90c6 7381 ea71 50ff b28b .....*..s..qP...
0x0020 8010 8218 97b0 0000 0101 080a a54c 4fed .............LO.
0x0030 1185 1083 696e 7465 6765 723b 3131 3739 ....integer;1179
0x0040 3538 0a61 3d45 6e64 4f6e 6552 756c 6545 58.a=EndOneRuleE
0x0050 6e64 nd
16:59:51.236763 netsaint.37062 > streaming-server.rtsp: R 1358934667:1358934667(0) win 0 (DF)
0x0000 4500 0028 0000 4000 ff06 2f78 c2ec e2e9 E..(.. at .../x....
0x0010 c343 e33d 90c6 022a 50ff b28b 0000 0000 .C.=...*P.......
0x0020 5004 0000 cd0d 0000 P.......
16:59:51.276763 streaming-server.rtsp > netsaint.37062: P 4614:5232(618) ack 111 win 33304 <nop,nop,timestamp 2773241837 293933187> (DF)
0x0000 4500 029e 1e46 4000 3906 d4bc c343 e33d E....F at .9....C.=
0x0010 c2ec e2e9 022a 90c6 7381 f019 50ff b28b .....*..s...P...
0x0020 8018 8218 a8af 0000 0101 080a a54c 4fed .............LO.
0x0030 1185 1083 7468 203c 2032 3630 3030 292c ....th.<.26000),
0x0040 4176 6572 6167 6542 616e 6477 6964 7468 AverageBandwidth
0x0050 3d31 =1
16:59:51.276763 netsaint.37062 > streaming-server.rtsp: R 1358934667:1358934667(0) win 0 (DF)
0x0000 4500 0028 0000 4000 ff06 2f78 c2ec e2e9 E..(.. at .../x....
0x0010 c343 e33d 90c6 022a 50ff b28b 0000 0000 .C.=...*P.......
0x0020 5004 0000 cd0d 0000 P.......
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