[EMAIL PROTECTED] wrote:
Thanks Peter for your answer . you said :
You *can never* see these errors in Tomcat, because Tomcat is never
aware that the connection was received. The operating system's
TCP/IP stack has received the incoming SYN, tried to queue the
connection request on Tomcat's accept queue, failed, and simply
sends a RST to close the connection.
What do these jargons SYN and RST actually mean ? I do not know TCP IP
details .
SYN and RST are two "types" of TCP/IP packets.
Roughly :
- a SYN packet is sent by a client to a server as the first packet, to
open a new TCP/IP connection.
- a RST packet is sent by either side to the other, to indicate the end
of the connection. After sending this packet, the sender closes the
socket, and when receiving the RST, the receiver should close the socket
on its side.
Between your client and Tomcat, there is, on each side, the TCP/IP
"stack", which is the series of operating-system layers of software that
manage the TCP/IP connection between them. On each side, the
application (e.g. browser on one side, Tomcat on the other) sits "on
top" of this TCP/IP stack.
This "stack" is what allows an application to not have to worry about
the underlying details of the connection, and see the connection as just
an input or output stream to read from or write to.
When the client wants to open a connection to the Tomcat server, it asks
its own TCP/IP stack to open a TCP/IP connection to the Tomcat host
system. The client's TCP/IP stack sends a SYN packet to the server.
The TCP/IP stack on the server side receives this request, but notices
that there are no more resources available to establish this connection,
and so it answers directly to the TCP/IP stack of the sender :
"impossible, sorry". It sends a RST packet to say that.
The TCP/IP stack of the client receives this packet, telling it that the
server refused to establish the connection. It then tells the client
software (the browser) : "could not establish connection". So the
client knows.
But on the server, because this happened at the level of the server
TCP/IP stack, Tomcat is not even aware that this has happened. So of
course it cannot log it anywhere.
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