Subject: data session hungs

From: "Barreira, Fernando [IT]" <[email-masked]>
Date: Fri, 29 Dec 2000 10:52:15 -0500

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hi there,

i have been investigating a weird situation in which when a user connects to
a specific internet ftp site via the fwtk ftp-gw,  very often during a file
transfer (or just by issuing the command "ls") , the data session stays hung
and can't get the ftp prompt back.

however, if i try ftp from the command line of the machine that has the fwtk
ftp-gw, i never see the problem.

since this only happens when connectiong to a specific site, i first thought
it was a problem on the remote ftp site, now i am beginning to wonder if the
fwtk ftp-gw is causing it since i don't see a problem when bypassing the
ftp-gw.

i am using an ultra2 with solaris 5.6, and fwtk version 2.1
the remote end uses "lsftp1a Microsoft FTP Service (Version 4.0)"

does anyone know if a similar situation has been reported and if there are
any bugs with fwtk that can trigger this?
any help would be appreciated. thanks.

---

From: Charles Robinson <[email-masked]>
Date: Fri, 29 Dec 2000 12:23:58 -0500 (EST)

Yes, the problem is with the ftp-gw. 
when doing a "ls" or "dir" or "send" in passive mode the data socket must
connect to the client or host. When the data socket can not be established
the process will hang. ftp error 425 or 426 I believe (check the ftp
client logs) This usually means that your client is behind a firewall that
does not allow that traffic on the port & is rejecting it. In active
environment your clients firewall must allow ftp over "high" ports.
or else it will hang. 

I hope this helps a little. 
Let me know if I was unclear on anything.

~~~~~~~~~~~~~~~~
Charles Robinson
Network Security Administrator
Professional Examination Service
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