[Techtalk] Slow networking connection

Raven, corporate courtesan raven at oneeyedcrow.net
Wed Jan 30 14:03:44 EST 2002

Heya --

Quoth coldfire (Wed, Jan 30, 2002 at 12:04:04PM -0500):
> > Does the ftp session get established (as in you can xfer files) or does it
> > just take ages and ages to get authenticated?
> > 
> > If it's the latter it is usually something to do with forward or reverse
> > DNS lookups, and the ftp server requiring a forward or reverse lookup
> > before authenticating a login.
> if it was waiting for dns lookups to complete, it would affect all
> services .. not just ftp.

	It all depends on how it's doing the name lookups.  If it's just
vanilla DNS resolution, then yes, "telnet myhost" would take just as
long as "ftp myhost".  But there are cases where FTP servers will
attempt to do a reverse lookup on an IP as well, and if your
in-addr.arpa's aren't in order, that can take forever (and so you have
to wait for the timeout).  If your FTP server is set up like this, then
"telnet" will be as fast as your network, but "ftp"
may take forever, because it's waiting on that reverse DNS lookup to
time out.

	How are you connecting, in general?  By IP or by name?  Do you
have both forward and reverse DNS set up for your network?

	What FTP server are you using?  How to disable the reverse
lookups depends on whether it's wu-ftpd, ProFTPd, PureFTPd, or whatever.

	I don't know offhand what the option is for wu-ftpd; I haven't
used it in years.

	For ProFTPd, in your config file have

      UseReverseDNS                   off
      IdentLookups                    off

	For PureFTPd, invoke the daemon with the -H option to turn this

> as for ftp .. is it the transfer speeds specifically that are taking a
> while?

	Also, is there a firewall between the two?  There's a big known
issue with firewalls and certain sorts of FTP -- you generally have to
either specify ports allowed through the firewall if you're using active
mode FTP, or enable passive mode FTP instead.

"I'm not good at running.  But I can yell really loudly.  That works too."
  -- Paul, on pursuit

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