Vulnerability Development mailing list archives
Re: FreeBSD listen()
From: poptix () POPTIX NET (Matthew S. Hallacy)
Date: Sat, 30 Oct 1999 18:22:39 -0500
On Thu, 28 Oct 1999, CyberPsychotic wrote:
~ :This fact causes problems. Some application (for example ftp server in ~ :passive mode or ftp client in active mode) use ~ :listen(data, 1); ~ :accept(data,...); ~ :close(data); ~ :to limit the number of incoming data connections to exactly one. If ~ :second connection is not rejected it makes possible attack to inject ~ :or intercept data between server and client as described in NAI ~ :bulletin That is a ftp daemon/client(depending whether it's an active or passive mode), which should take care of accepting only single connection and only from proper source (which is surprisely being ignored by some daemons, such as ncftpd f.e.).
Some programs, such as fxp rely on this kind of behaviour, while i agree that there should be checking, we dont want to break good programs ...
However even ncftpd closes all the incoming connections to the port once the first one has been accepted. Same goes with my ftp client. (shipped r.h. 6.0). So I don't think there're any security issues except syn-flooding, are involved here.
Current thread:
- ICQ 2000, (continued)
- ICQ 2000 Elias Levy (Oct 25)
- Re: ICQ 2000 Blue Boar (Oct 25)
- Re: ICQ 2000 Sean Burford (Oct 25)
- Re: ICQ 2000 Brad Griffin (Oct 26)
- Re: ICQ 2000 Blue Boar (Oct 25)
- icq2000 Brad Griffin (Oct 26)
- Re: ICQ 2000 Damm, Mike (Oct 26)
- Re: ICQ 2000 Brad Griffin (Oct 26)
- FreeBSD listen() 3APA3A (Oct 27)
- Re: FreeBSD listen() CyberPsychotic (Oct 27)
- Re: FreeBSD listen() 3APA3A (Oct 29)
- Re: FreeBSD listen() Matthew S. Hallacy (Oct 30)
- Fw: Trojan/Worm on one of your pages and spams ICQ users. BrainMaster (Oct 28)
- Re: FreeBSD listen() David Schwartz (Oct 28)
- Re: FreeBSD listen() 3APA3A (Oct 29)
- Re: FreeBSD listen() David Schwartz (Oct 30)
- Re: FreeBSD listen() 3APA3A (Oct 31)
- ICQ 2000 Elias Levy (Oct 25)
- Re: FreeBSD listen() Sebastian (Oct 28)
- Re: FreeBSD listen() 3APA3A (Oct 29)
- Re: FreeBSD listen() Warren Young (Oct 28)
- Re: ICQ 2000 Bernie Cosell (Oct 27)
- Re: ICQ 2000 Ripple (Oct 26)