Re: FTP site

[Nathan E Norman <finn@midco.net>]

On Mon, 1 Jun 1998, matthew.r.pavlovich.1 wrote:

: The problem is not the server being up or down.  When it is up, I am not
: able to connect because the server cannot reverse-resolve my hostname.
: 
: Connected to ike.egr.msu.edu.
: 421 Service not available, remote server has closed connection
: ftp> 
: 
: Connected to santanni.cc.gatech.edu.
: 421 Service not available, remote server has closed connection
: ftp> 
: 
: These servers both cannot resolve my hostname.  I am not alone with this
: problem, there are many people that use dial-up connections experiencing
: the same thing.
: 
: -Matt

Call your ISP and tell them to fix their inverse mapping.

This is what happens:

You connect to a server.  That server has your IP address (from the
packets) so in does a reverse lookup.  If your IP was, for example,
208.150.221.24, that would resolve to "pc-24.pix-pool1.midco.net"
(reverse lookups are where the "in-addr.arpa" domains come into play.
All ISPs should know how to do this.  Some don't)

However, the server is a bit paranoid, as it should be, so it attempts
to resolve the name it just received and see if that resolves back to
the IP.  "pc-24.pix-pool1.midco.net" does indeed resolve to
208.150.221.24.

However, if you had connected from 208.146.80.88 (which is impossible,
btw - hence the current DNS mappings :) a reverse lookup would yield
"nobody.midco.net".  However, "nobody.midco.net" does not resolve!  The
server would note this and refuse service.

However, in the case of a dialup ISP, all dialup lines should have
successful forward and reverse resolution. 

Good luck!

--
Nathan Norman
MidcoNet - 410 South Phillips Avenue - Sioux Falls, SD  57104
mailto://finn@midco.net   http://www.midco.net
finger finn@kepler.midco.net for PGP Key: (0xA33B86E9)



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