Date: Fri, 16 Feb 2001 08:50:38 -0800 (PST) From: Richard Hodges <rh@matriplex.com> To: Dale Chulhan - Home <dchulhan@uwi.tt> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Cannot create raw socket connections Message-ID: <Pine.BSF.4.10.10102160831210.87873-100000@mail.matriplex.com> In-Reply-To: <3A8C88D0.DC9ED9AA@uwi.tt>
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On Thu, 15 Feb 2001, Dale Chulhan - Home wrote:
> I have a pal trying to do a tool for measurement of bandwidth on a bsd
> machine.
>
> He says:
>
> Everytime I open a raw socket connection ( send FIN to expect RST or
> something like that ).
There should be no problem with sending a TCP FIN on a raw socket.
But the returning RST will be eaten by the TCP protocol. Your raw
socket will not receive it. (ref: Stevens UNP v1, p 659)
> The socket is killed.
That is most strange... You mean to say that the next sendto() or
recvfrom() returns EBADF? What version of FreeBSD is this?
> He concluded that the router he is going through is dropping the packets
> some how on their way out or the connection is being killed on the way
> back in.
The router could be dropping packets. If you have access, it should
not take much time to add a specific access list rule to log those
packets to see if they are going through.
> He says there is a third possibility that the kernel actually discards
> the packets. Said he found it in a man page some where?
Unless you have a firewall installed, the kernel should send all
packets from a raw socket, and pass all incoming packets to your
socket, except UDP, TCP, and ICMP echo/timestamp/mask.
-Richard
-------------------------------------------
Richard Hodges | Matriplex, inc.
<title> | 769 Basque Way
rh@matriplex.com | Carson City, NV 89706
775-886-6477 | www.matriplex.com
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