Re: Strange port 20/21 problem with Netgear RT314 Router
Available news archives: comp.lang.tcl - comp.lang.python - comp.security.firewalls - sci.crypt - comp.lang.php - comp.lang.javascript
Google
 
Web news.hping.org


comp.security.firewalls archive

Re: Strange port 20/21 problem with Netgear RT314 Router

From: Alun Jones <alun@texis.invalid>
Date: Tue Nov 29 2005 - 04:52:28 CET

QV wrote:
> "Triffid" <triffid@nebula.net> wrote in message
> news:ztcif.36605$gK4.1183753@news20.bellglobal.com...
>>
>> The router probably assumes you're running an ftp server when you tell
>> it to forward port 21, so you'll be needing port 20 for the data
>> connections.
>>
>> http://slacksite.com/other/ftp.html
>
> It seems dangerous for a router to "assume" anything, but the Netgear
> appears to be doing just that in the case of port 20. It makes me wonder
> what else it assumes.

If it really is assuming that port 20 needs to be open for inbound TCP
connections, then it's dopey. 20 is the source port for _outbound_ FTP data
connections on TCP. It's not the destination port.

Of course, if it's working as a straight IP packet filter, it has to allow
for traffic in both directions to and from port 20.

Alun.
~~~~
[Please don't email posters, if a Usenet response is appropriate.]

-- 
Texas Imperial Software   | Find us at http://www.wftpd.com or email
23921 57th Ave SE         | alun@wftpd.com.
Washington WA 98072-8661  | WFTPD, WFTPD Pro are Windows FTP servers.
Fax/Voice +1(425)807-1787 | Try our NEW client software, WFTPD Explorer.
Received on Sat Dec 3 04:18:41 2005