Re: FreeBSD listen()

[scut () NB IN-BERLIN DE (Sebastian)]

On Sun, 31 Oct 1999, CyberPsychotic wrote:

Hi.

> for me just fine), I just got points that ftp daemon should do appropriate
> things instead. :)) Quite humorous but looks like ftp developers would
> claim that not their code, but kernel should take care of the solution to
> the problem.. oh well, that is life :)

It may not be as easy as it looks. If you just go for "ftp daemon should
check source IP address of the data transfer", it would have the following
consequences:

   - effectivly proxy ftp transfers are denied, since the source IP is not
     the one of the client but the one of the remote ftp server
   - you'd get problems when using ftp bouncers or ftp bounce networks
     (such as bnc4all http://bnc4all.ftp4all.de/, redirect4all or the
     rftpd bouncer)
   - it might confuse load balancing application layer gateways
   - RFC 959 doesn't mention source IP checking anywhere, therefore it
     would be a doubtable selfmade addon

On the other hand random ports choosen by the server violate the RFC, too:
"Every FTP implementation must support the use of the default data ports,
and only the USER-PI can initiate a change to non-default ports."

> -Fyodor

ciao,
scut / team teso
[http://teso.scene.at/]

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