Re: Scanner

[Brian Candler <B.Candler at pobox.com>]

On Wed, Feb 19, 2003 at 01:12:06PM +0300, Mark Tinka wrote:
> I am trying to setup a virus scanner that listens on port 25, traps the
> e-mail, scans it and then passes it on to a pre-defined mail server for
> local delivery.
> 
> I've installed the scanner, but when I try to telnet port 25 for a banner,
> the connection is closed after a connection has been extablished. It's quite
> odd. It won't accept outgoing e-mail either.
> 
> I have run strace against the telnet command, and need some help trying to
> understand the output. System is SuSE Linux with kernel 2.4.19.

Well, tracing the client side is not going to tell you much. It just shows
you that it connected:

> connect(3, {sin_family=AF_INET, sin_port=htons(25), sin_addr=inet_addr("216.104.200.15")}}, 16) = 0

Successful connection (return code 0)

> write(1, "Connected to 216.104.200.15.\r\n", 30Connected to 216.104.200.15.) = 30
> write(1, "Escape character is \'^]\'.\r\n", 27Escape character is '^]'.) = 27

Reports the fact to the local terminal.

> select(4, [0 3], [], [3], {0, 0})       = 1 (in [3], left {0, 0})
> recv(3, "", 8192, 0)                    = 0

The far end disconnected (select reports an event on fd 3, but recv returns
a count of 0 bytes, which indicates an error condition)

So, you need to be looking at the server end to see what is being logged, to
find out why it is dropping the call. You didn't say what MTA or anti-virus
package you are using there!

Regards,

Brian.

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