Re: iptables REJECT types for UDP (if any)

From: Philipp Schulte (pschulte@uni-duisburg.de)
Date: 11/17/02

  • Next message: Simon Byrnand: "RE: iptables REJECT types for UDP (if any)" 
    Date: Sun, 17 Nov 2002 03:11:16 +0100
From: Philipp Schulte <pschulte@uni-duisburg.de>
To: focus-linux@securityfocus.com

    Miguel Angel Rodríguez Jódar wrote:

    > > using -j DROP as a target, what I want to know is what types
    > > of REJECT
    > > can be used for UDP packets? Thanks.
    >
    > AFAIK, UDP packets are not realiable

    This is misleading. UDP (as opposed to TCP) is a connection-less
    protocol. That means that UDP itself doesn't check if packets made
    their way. But this doesn't make the UDP-packets themselves less
    reliable than TCP-packets.

    > haven't got things like the RST option in their headers as TCP
    > packets have, so dropping it is your only choice.

    While it is true that UDP doesn't know such a thing as RST, dropping
    them is _not_ the only choice. The equivalent to TCP-RST would be to
    send an ICMP-PortUnreachable.
    Phil

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