FreeBSD FTP problem

[Ryan Thompson]

Arcadius A. wrote to Ryan Thompson and FreeBSD Questions:

> > > but nothing more.... just the same arror as the one you've described:
> > > "... 425 can't build data connection: operation timed out ..." :-(((
> > >
> > > Do you have any idea about how to get around this?
> >
> > Well, in my case, it turned out to be pilot error... FTP is a tricky
> > protocol to allow through default-deny firewalls, and I had simultaneous
> > bugs in my firewall config *and* FTPd config, with respect to passive
> > transfers. It took me a while to spot.
> >
> > Check your firewall config carefully, and make sure you have a good
> > understanding of how the FTP protocol works (in active and passive
> > modes). Completely open your firewall temporarily (i.e., ipfw add 201
> > allow ip from any to any) and verify that things work there. If things
> > work there (or fail differently), the problem is with your firewall (and
> > possibly FTPd configuration, if you're using the ephemeral port range
> > for PASV). If your tests fail in *exactly* the same manner as before,
> > including the same timeout delays, you can ignore your firewall for the
> > time being (but leave it open until you get FTP working, and *then*
> > restrict it, so you're only testing one unknown at a time). Try running
> > tcpdump and sockstat on the server to see what's coming and going for
> > FTP traffic. /ports/net/trafshow might be helpful, too.
> >
>
> Hello!
> Thanks for the reply!
> But I'm not running any firewall on my server...

Ahh. So you're *not* having exactly the same problem. :-)

> So, my problem shouldn't be with the firewall on my server...
>
> About the configuration of  FTPd, I cannot find the config file
> (ftpd.conf or ftpd.config or ftpd.cf )on my server(FreeBSD4.8 stable,
> built yesterday).

>From ftpd(8):
FILES
     /etc/ftpusers    List of unwelcome/restricted users.
     /etc/ftpchroot   List of normal users who should be chroot'd.
     /etc/ftphosts    Virtual hosting configuration file.
     /etc/ftpwelcome  Welcome notice.
     /etc/ftpmotd     Welcome notice after login.
     /var/run/nologin
                      Displayed and access refused.
     /var/log/ftpd    Log file for anonymous transfers.

> Note that I'm trying to connect to FreeBSD from a windows
> workstation....  both the workstation and the FreeBSD server are in
> the same LAN.... From my Windows box, I can easilly connect via FTP to
> other Linux sercers in my LAN or even out of the LAN.. But when I
> connect to my FreeBSD server, it connecs well... but I cannot do
> anything useful on the server.... I get the error "...425 can't build
> data connection: operation timed out..."

Try both active and passive modes for transfer. If you really have no
firewall between the client and the server (remember the entire path
from application to application is important), and there is no address
translation going on, you should have no issues either way with the
stock configurations of Windows and FreeBSD.

If, on the other hand, you're running any sort of packet filter or
"Personal Firewall" on the Windows machine, or using "Internet
Connection Sharing", or if your "LAN" is more than an unmanaged link
layer switch/hub, you're no longer running a stock config, and the
results may be unpredictable. From your description, your problems do
seem to point to a misconfiguration of FreeBSD, but I wouldn't bet my
server farm on that quite yet.

I'd highly recommend you take my earlier advice and run tcpdump and/or
trafshow on the server to see what's really going on... and, if
possible, compare with similar output from the client. Try connecting
with different clients, too. If you aren't familiar with analysis using
tcpdump, try some Googling on the subject, or ask for help. Equivalent
output from a complete FTP client session would also be extremely
helpful in diagnosing your problem.

At this point, nobody here will be able to do more than go on a hunch as
to what's causing the problem. There is probably a simple answer, but I
can think of dozens of ways to reproduce the error message you've
reported.

> My server was running FreeBSD4.6 before and I didn't have any trouble
> with FTPd .... I just upgraded yesterday.... and still, I haven't
> noticed this problem.... I start getting this error just a while
> ago... :-( ... I've rebooted the server... but it didn't help

Assuming you kept backups of your config, check the diffs carefully.
Don't suppose you can revert back to your old config and verify that
this is still an issue?

- Ryan

-- 
  Ryan Thompson <ryan at sasknow.com>

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