From owner-freebsd-questions Sat Feb 19 18:43:48 2000 Delivered-To: freebsd-questions@freebsd.org Received: from if.scientech.com (eaglerock.if.scientech.com [198.60.85.3]) by hub.freebsd.org (Postfix) with ESMTP id BC09937BC88 for ; Sat, 19 Feb 2000 18:43:44 -0800 (PST) (envelope-from cmott@scientech.com) Received: from if.scientech.com (IDENT:cmott@if.scientech.com [10.128.1.6] (may be forged)) by if.scientech.com (8.9.3/8.9.3) with ESMTP id TAA30809 for ; Sat, 19 Feb 2000 19:43:43 -0700 Date: Sat, 19 Feb 2000 19:43:43 -0700 (MST) From: Charles Mott To: freebsd-questions@freebsd.org Subject: Re: Redirecting/mapping ports to a local machine... help! In-Reply-To: <20000219213848.H60348@cc942873-a.ewndsr1.nj.home.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > Many people use ftp in non-passive mode from behind natd > > without any problems. > > Many people get lucky then. From the alias_ftp.c source, > > For this routine to work, the PORT command must fit entirely > into a single TCP packet. This is typically the case, but exceptions > can easily be envisioned under the actual specifications. I wrote the alias_ftp.c source code and the comment that you cite. It is unusual to see a PORT command divided into more than one packet. There is a firewall toolkit that deliberately does this, but I know of no other examples. > > > > Use of a control channel and a data channel is a basic part of the ftp > > > protocol. See RFC 959. Unimplemented RFC 2428 might be interesting too. > > But we need to point out that the this special handling of FTP by NAT > is for _clients_ behind the NAT box only, not servers. > -- > Crist J. Clark cjclark@home.com > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message