Meino Christian Cramer <root@solfire.ludwigsburg.netsurf.de> writes:
> Everytime I connect to ftp.xcf.berkeley.edu
> (and some other sites...) the connection
> and login itsself works fine.
>
> But any attempt to transfer data (even "ls")
> fails. The modem shows some transfers, then
> the transfer stops. Nothing more happens.
>
> The line is dead.
I have the same problem. Here is a tcpdump
[129.187.24.119 is my machine: 2.1.36, connected over a ppp dialup line,
128.32.43.201 is ftp.xcf.berkeley.edu]
10:12:06.557010 129.187.24.119.1515 > 128.32.43.201.ftp: S 804210132:804210132(0) win 8192 <mss 1484> (DF)
10:12:06.934987 128.32.43.201.ftp > 129.187.24.119.1515: S 1507392000:1507392000(0) ack 804210133 win 16384
10:12:06.935121 129.187.24.119.1515 > 128.32.43.201.ftp: . ack 1 win 1484 (DF)
10:12:07.435002 128.32.43.201.ftp > 129.187.24.119.1515: P 1:78(77) ack 1 win 16384
...seems to be fine
10:12:07.435145 129.187.24.119.1515 > 128.32.43.201.ftp: . ack 78 win 2968 (DF) [tos 0x10]
hmm, this ack is too early
10:12:07.438960 129.187.24.119.1515 > 128.32.43.201.ftp: P 1:11(10) ack 78 win 4452 (DF) [tos 0x10]
my machine starts the ftp login
10:12:07.865033 128.32.43.201.ftp > 129.187.24.119.1515: P 78:146(68) ack 11 win 16384
10:12:07.866747 129.187.24.119.1515 > 128.32.43.201.ftp: P 11:33(22) ack 146 win 4452 (DF) [tos 0x10]
10:12:08.255008 128.32.43.201.ftp > 129.187.24.119.1515: P 146:194(48) ack 33 win 16384
10:12:08.256609 129.187.24.119.1515 > 128.32.43.201.ftp: P 33:39(6) ack 194 win 4452 (DF) [tos 0x10]
10:12:08.575013 128.32.43.201.ftp > 129.187.24.119.1515: P 194:213(19) ack 39 win 16384
10:12:08.904997 129.187.24.119.1515 > 128.32.43.201.ftp: . ack 213 win 4452 (DF) [tos 0x10]
again too early
10:12:13.825724 129.187.24.119.1515 > 128.32.43.201.ftp: P 39:65(26) ack 213 win 4452 (DF) [tos 0x10]
10:12:14.175014 128.32.43.201.ftp > 129.187.24.119.1515: P 213:243(30) ack 65 win 16384
10:12:14.176776 129.187.24.119.1515 > 128.32.43.201.ftp: P 65:71(6) ack 243 win 4452 (DF) [tos 0x10]
10:12:14.535010 128.32.43.201.ftp-data > 129.187.24.119.1555: S 1509056000:1509056000(0) win 16384
10:12:14.535206 129.187.24.119.1555 > 128.32.43.201.ftp-data: S 1726925241:1726925241(0) ack 1509056001 win 8192 <mss 0> (DF)
^^^^^^^^
this seems to be the linux bug
10:12:14.595028 128.32.43.201.ftp > 129.187.24.119.1515: . ack 71 win 16384
10:12:14.935010 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
three way handshake for the ftp data connection
10:12:14.965003 128.32.43.201.ftp > 129.187.24.119.1515: P 243:296(53) ack 71 win 16384
10:12:14.975027 129.187.24.119.1515 > 128.32.43.201.ftp: . ack 296 win 4452 (DF) [tos 0x10]
it seems the machine can't handle a 0 mss and starts flooding
10:12:14.985013 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
10:12:14.995050 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
10:12:15.015002 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
10:12:15.025075 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
10:12:15.045009 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
10:12:15.055043 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
10:12:15.075010 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
10:12:15.094998 128.32.43.201.ftp-data > 129.187.24.119.1555: . ack 1 win 16384
[... it continues like this ...]
-Andi