Ftp-WG: PASV and Snap servers

Jim Matthews <[email protected]> Wed, 18 Dec 2002 12:12:57 -0500
Newsgroups gmane.ietf.ftpext
Message-ID <p0530099bba2659709616@[192.168.1.17]>
>Me, I know (almost) nothing, but I'm curious.
>
>Can you share more of the trace of Fetch talking?  The
>more the better, including at least the time from the
>PASV command to a little past the 450 reply?
>
>Can we contrast that failing trace with the trace of
>what does work, with such as Mac OS X ftp -d?

Sure, here are the two traces, with addresses and hostnames edited 
for the sake of the customer's privacy.

The one difference that I notice is that Fetch sends the LIST command 
right after the SYN for the data connection, while the OS X ftp 
client does not send LIST until the data connection is actually 
established.  Should clients make the data connection first and then 
send the data-transferring command?

OS X ftp:

17:13:19.237876 192.168.1.17.49216 > some.server.com.ftp: P 
3507872715:3507872721(6) ack 2612625465 win 33580 (DF) [tos 0x10]
0x0000   4510 002e 83ca 4000 4006 ee7e c0a8 0111        E.....@.@..~....
0x0010   642c 3f8b c040 0015 d115 e3cb 9bb9 8039        .,[email protected]
0x0020   5018 832c 225d 0000 5041 5356 0d0a             P..,"]..PASV..
17:13:19.435789 some.server.com.ftp > 192.168.1.17.49216: P 1:51(50) 
ack 6 win 8760
0x0000   4500 005a 101a 0000 0f06 d313 642c 3f8b        E..Z.........,?.
0x0010   c0a8 0111 0015 c040 9bb9 8039 d115 e3d1        [email protected]....
0x0020   5018 2238 b72e 0000 3232 3720 456e 7465        P."8....227.Ente
0x0030   7269 6e67 2050 6173 7369 7665 204d 6f64        ring.Passive.Mod
0x0040   6520 2831 3939 2c34 342c 3633 2c31 3339        e.(100,44,63,139
0x0050   2c34 2c31 3231 292e 0d0a 20f1 a452             ,4,121)......R
17:13:19.437486 192.168.1.17.49219 > some.server.com.1145: S 
914967343:914967343(0) win 32768 <mss 1460,nop,wscale 
0,nop,nop,timestamp 490799 0> (DF)
0x0000   4500 003c 83cb 4000 4006 ee7f c0a8 0111        E..<..@.@.......
0x0010   642c 3f8b c043 0479 3689 4b2f 0000 0000        .,?..C.y6.K/....
0x0020   a002 8000 c89f 0000 0204 05b4 0103 0300        ................
0x0030   0101 080a 0007 7d2f 0000 0000                  ......}/....
17:13:19.566441 192.168.1.17.49216 > some.server.com.ftp: . ack 51 
win 33580 (DF) [tos 0x10]
0x0000   4510 0028 83cc 4000 4006 ee82 c0a8 0111        E..(..@.@.......
0x0010   642c 3f8b c040 0015 d115 e3d1 9bb9 806b        .,[email protected]
0x0020   5010 832c d2d4 0000                            P..,....
17:13:19.627530 some.server.com.1145 > 192.168.1.17.49219: S 
2633463297:2633463297(0) ack 914967344 win 8760 <mss 1460>
0x0000   4500 002c 101b 0000 0f06 d340 642c 3f8b        E..,.......@.,?.
0x0010   c0a8 0111 0479 c043 9cf7 7601 3689 4b30        .....y.C..v.6.K0
0x0020   6012 2238 53fe 0000 0204 05b4 0000 d321        `."8S..........!
0x0030   75c8                                           u.
17:13:19.627616 192.168.1.17.49219 > some.server.com.1145: . ack 1 
win 33580 (DF)
0x0000   4500 0028 83cd 4000 4006 ee91 c0a8 0111        E..(..@.@.......
0x0010   642c 3f8b c043 0479 3689 4b30 9cf7 7602        .,?..C.y6.K0..v.
0x0020   5010 832c 0ac7 0000                            P..,....
17:13:19.629290 192.168.1.17.49216 > some.server.com.ftp: P 6:12(6) 
ack 51 win 33580 (DF) [tos 0x10]
0x0000   4510 002e 83ce 4000 4006 ee7a c0a8 0111        E.....@[email protected]....
0x0010   642c 3f8b c040 0015 d115 e3d1 9bb9 806b        .,[email protected]
0x0020   5018 832c 261f 0000 4c49 5354 0d0a             P..,&...LIST..
17:13:19.844390 some.server.com.ftp > 192.168.1.17.49216: P 
51:105(54) ack 12 win 8760
0x0000   4500 005e 101c 0000 0f06 d30d 642c 3f8b        E..^.........,?.
0x0010   c0a8 0111 0015 c040 9bb9 806b d115 e3d7        [email protected]....
0x0020   5018 2238 8935 0000 3132 3520 4461 7461        P."8.5..125.Data
0x0030   2063 6f6e 6e65 6374 696f 6e20 616c 7265        .connection.alre
0x0040   6164 7920 6f70 656e 3b20 7472 616e 7366        ady.open;.transf
0x0050   6572 2073 7461 7274 696e 672e 0d0a 2765        er.starting...'e
0x0060   2a67                                           *g

Fetch:

17:14:32.104223 192.168.1.17.51742 > some.server.com.ftp: P 24:30(6) 
ack 147 win 33580 (DF)
0x0000   4500 002e 83e3 4000 4006 ee75 c0a8 0111        E.....@[email protected]....
0x0010   642c 3f8b ca1e 0015 3450 0ec9 9c57 1dc9        .,?.....4P...W..
0x0020   5018 832c ec19 0000 5041 5356 0d0a             P..,....PASV..
17:14:32.294461 some.server.com.ftp > 192.168.1.17.51742: P 
147:197(50) ack 30 win 8760
0x0000   4500 005a 1028 0000 0f06 d305 642c 3f8b        E..Z.(.......,?.
0x0010   c0a8 0111 0015 ca1e 9c57 1dc9 3450 0ecf        .........W..4P..
0x0020   5018 2238 80ea 0000 3232 3720 456e 7465        P."8....227.Ente
0x0030   7269 6e67 2050 6173 7369 7665 204d 6f64        ring.Passive.Mod
0x0040   6520 2831 3939 2c34 342c 3633 2c31 3339        e.(100,44,63,139
0x0050   2c34 2c31 3232 292e 0d0a 588c f876             ,4,122)...X..v
17:14:32.299638 192.168.1.17.51744 > some.server.com.1146: S 
563990928:563990928(0) win 32768 <mss 1460,nop,wscale 
0,nop,nop,timestamp 490944 0> (DF)
0x0000   4500 003c 83e4 4000 4006 ee66 c0a8 0111        E..<..@[email protected]....
0x0010   642c 3f8b ca20 047a 219d d190 0000 0000        .,?....z!.......
0x0020   a002 8000 c89f 0000 0204 05b4 0103 0300        ................
0x0030   0101 080a 0007 7dc0 0000 0000                  ......}.....
17:14:32.302079 192.168.1.17.51742 > some.server.com.ftp: P 30:36(6) 
ack 197 win 33580 (DF)
0x0000   4500 002e 83e5 4000 4006 ee73 c0a8 0111        E.....@[email protected]....
0x0010   642c 3f8b ca1e 0015 3450 0ecf 9c57 1dfb        .,?.....4P...W..
0x0020   5018 832c efdb 0000 4c49 5354 0d0a             P..,....LIST..
17:14:32.489213 some.server.com.1146 > 192.168.1.17.51744: S 
2642845697:2642845697(0) ack 563990929 win 8760 <mss 1460>
0x0000   4500 002c 1029 0000 0f06 d332 642c 3f8b        E..,.).....2.,?.
0x0010   c0a8 0111 047a ca20 9d86 a001 219d d191        .....z......!...
0x0020   6012 2238 ae1b 0000 0204 05b4 0000 77ca        `."8..........w.
0x0030   3686                                           6.
17:14:32.489306 192.168.1.17.51744 > some.server.com.1146: . ack 1 
win 33580 (DF)
0x0000   4500 0028 83e6 4000 4006 ee78 c0a8 0111        E..(..@[email protected]....
0x0010   642c 3f8b ca20 047a 219d d191 9d86 a002        .,?....z!.......
0x0020   5010 832c 64e4 0000                            P..,d...
17:14:32.530748 some.server.com.ftp > 192.168.1.17.51742: P 
197:289(92) ack 36 win 8760
0x0000   4500 0084 102a 0000 0f06 d2d9 642c 3f8b        E....*.......,?.
0x0010   c0a8 0111 0015 ca1e 9c57 1dfb 3450 0ed5        .........W..4P..
0x0020   5018 2238 bcac 0000 3435 3020 4461 7461        P."8....450.Data
0x0030   2074 7261 6e73 6665 7220 6e6f 7420 696d        .transfer.not.im
0x0040   706c 656d 656e 7465 6420 666f 7220 636c        plemented.for.cl
0x0050   6965 6e74 2064 6566 6175 6c74 2064 6174        ient.default.dat
0x0060   6120 706f 7274 2e20 4e65 6564 2027 504f        a.port..Need.'PO
0x0070   5254 2720 636f 6d6d 616e 6420 6669 7273        RT'.command.firs
0x0080   742e 0d0a 2d94 17e4                            t...-...
-- 
Jim Matthews
Fetch Softworks
http://fetchsoftworks.com