i486 - kernel 1.3.2, userland 1.3.1, ep0 "3Com 3C509 Ethernet".


Occasionally, I've found that when FTP'ing to my host using "passive"
direction for data-sessions it hangs.  Basically it just put out:

ftp> ls -l
227 Entering Passive Mode (xxx,xxx,xxx,xxx,14,156)

And it sits there. (took 6 "ls -l" before it happened this time)
If I then telnet to port 3740 (14, 156 = 0E9C = 3740) I get the ls -l
output just fine.

I thought perhaps it was my ip_fil rules, but I disabled it (ipf -D) and
it still happens.

This is what I see in tcpdump:

xxx.xxx.xxx.xxx is FTPD host, tested on NetBSD-1.3 ftpd, and lftpd-2.1

yyy.yyy.yyy.yyy is ftp-client host, clients tested are: NetBSD-ftp,
bpftp(win95), CuteFtp(win95)

13:07:13.981537 yyy.yyy.yyy.yyy.3198 > xxx.xxx.xxx.xxx.3740: S
3536172415:3536172415(0) win 8192 <mss 1460> (DF)

13:07:13.982232 xxx.xxx.xxx.xxx.3740 > yyy.yyy.yyy.yyy.3198: S
3249232900:3249232900(0) ack 3536172416 win 16384 <mss 1460>
 
and then nothing more.


These are the first few lines from tcpdump when I telnet to the
data-sessions port:

13:12:17.409641 yyy.yyy.yyy.yyy.3599 > xxx.xxx.xxx.xxx.3740: S
3536475942:3536475942(0) win 8192 <mss 1460> (DF)
13:12:17.411487 xxx.xxx.xxx.xxx.3740 > yyy.yyy.yyy.yyy.3599: S
3421755260:3421755260(0) ack 3536475943 win 16384 <mss 1460>
13:12:17.473413 yyy.yyy.yyy.yyy.3599 > xxx.xxx.xxx.xxx.3740: . ack 1 win
8760 (DF)
13:12:17.477838 xxx.xxx.xxx.xxx.3740 > yyy.yyy.yyy.yyy.3599: . ack 1 win
17520
13:12:17.548506 xxx.xxx.xxx.xxx.3740 > yyy.yyy.yyy.yyy.3599: .
1:513(512) ack 1 win 17520 [tos 0x8]
13:12:17.549182 xxx.xxx.xxx.xxx.3740 > yyy.yyy.yyy.yyy.3599: P
513:533(20) ack 1 win 17520 [tos 0x8]



Is this a know problem? Is there anything I can do to fix this?

Thanks for any reply!


-- 
Jorgen Lundman <lundman@argonaut.com>
Programmer & Unix Administrator
http://www.whiterose.net/users/lundman/
"Research indicate that only 20% of what goes wrong is actually my
fault"