Running More Than 24 Virtual Testers on a UNIX Agent
384
Appendix A - Configuring Local and Agent Computers
Controlling TCP Port Numbers
The
rtmstr_v
and
rtmstr_s
network services control the ports on the Local computer to
which the Agent communication software connects. These network services allow
tests to be run with Local and Agent computers on different networks separated by a
firewall, by controlling the ports to which the listening Local server processes bind.
In a test run involving Agents, there are multiple socket connections between the
Local computer and each Agent.
Connections made from the Local to the Agent computer are always made to a single
well-known port on which the Agent is listening. This port defaults to 8800.
Two connections are made from each Agent computer to the Local computer, one to a
Local server process named
rtvsrv
and another to a Local server process named
rtssrv
.
Each server process listens on a separate port. The processes do not bind to a specific
port; instead the Local computer's operating system chooses a port dynamically. The
Local computer then communicates these port values to the Agent during run
initialization. (Note that all Agents connect to the same two ports on the Local
computer.) These two dynamically chosen ports on the Local computer cause firewall
administration problems because the two ports to be used cannot be determined in
advance.
You can control this problem by using the optional presence of network services (the
traditional TCP/UDP network services defined in an
/etc/services
file, not to be
confused with an NT service). On NT, the services file is found in
drive\WINNT\system32\drivers\etc\services
. There is one entry per line, which lists
the service name, the port number, and the protocol (TCP or UDP).
Specifically, control over the ports is provided as follows:
rtvsrv
binds to the port (in priority order):
1
The value of the TCP service named
rtmstr_v
, if defined.
2
If not defined, a port dynamically chosen by the system.
rtssrv
binds to the port (in priority order):
1
The value of the TCP service named
rtmstr_s
, if defined.
2
If not defined, a port dynamically chosen by the system.
The ports defined by these two services are independent. That is, they do not need to
be adjacent nor related to the well-known Agent port of 8800. They do need to be
unique. We suggest using the ports 8801 and 8802 if they are not used for some other
service on the Local computer.
