Eric,
On 6/24/21 21:14, Eric Robinson wrote:
I guess I may have answered this question for myself. At least I can
simulate it with ncat. Note that I have two ncat sessions open to the
same remote server using the same source port, but with different source
IPs.
[root@testserver ~]# netstat -antp|grep ncat
tcp 0 0 192.168.11.215:3456 192.168.10.59:9000 ESTABLISHED
60946/ncat
tcp 0 0 192.168.10.58:3456 192.168.10.59:9000 ESTABLISHED
60920/ncat
What is the command-line you used to invoke those nc processes?
Presumably, you had to specifically tell each process which source
interface to use.
I haven't done this myself, but my guess would be that every outgoing
connection would use the default network interface appropriate for that
type of communication.
The IP/interface Tomcat uses to bind and listen for connections has no
bearing on which interface is chosen for outbound connections.
> Is there any reason why tomcat should not be expected to work the
same > way? And when I say tomcat, I really mean libraries like the mysql
> odbc connector that tomcat uses.
Oh, you're using Connector/J? Then you want this setting:
localSocketAddress
https://dev.mysql.com/doc/connector-j/5.1/en/connector-j-connp-props-connection-authentication.html
-chris
-----Original Message-----
From: Eric Robinson <eric.robin...@psmnv.com>
Sent: Thursday, June 24, 2021 3:19 PM
To: Tomcat Users List <users@tomcat.apache.org>
Subject: Re-Use TCP Source Ports if the Socket is Unique?
Two quick questions.
Question 1:
When tomcat creates a TCP connection to a remote server (for example, a
back-end database) tomcat is acting as the TCP client in that case. Does it use
the IP it is listening on as the source IP for its outbound client connection?
For example, Server1 has three IPs: 10.0.0.1 (primary), and two additional
IPs, 10.0.0.2 and 10.0.0.3. Tomcat is listening on 10.0.0.2. It receives a
request
that requires it to connect to a database server. When it creates a TCP
connection the database server, which IP does it use as the source address?
Question 2:
Suppose you have two instances of tomcat on the same server. TomcatA is
listening on 10.0.0.2 and TomcatB on 10.0.0.3. First, TomcatA establishes a
connection to a remote server from its source IP 10.0.0.2, source port 3456.
Can TomcatB, which is listening on a different IP, also establish a connection
to the remote database server using the same source port 3456, given that
the sockets is unique (different source IP)?
-Eric
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