Tcp/ip ports, Tcp/ip ports nat – Network Instruments GigaStor 114ff User Manual
Page 124

TCP/IP ports
Appendix A TCP/IP ports, NAT, and VPN
124
rev. 1
This section discusses the TCP/IP ports, NAT, and VPN.
TCP/IP ports
Observer and all Network Instruments probes use ports 25901 and 
25903 to communicate. These ports are registered ports to Network 
Instruments. 
All Network Instruments probes initiate connection with Observer 
using port 25901. Observer listens on port 25901. After a connection 
is established all communication between Observer and the probes 
occurs on port 25901, except probe redirection and administration, 
which uses port 25903.
Figure 85 Port connections
NAT
If you use network address translation (NAT) in your environment, 
you must make some configuration changes in Observer. Using the 
TCP/IP port information in “TCP/IP ports” on page 124, you should 
be able to set up the NAT properly. 
If the probe is outside the network where Observer is running, you 
must forward port 25901 from the probe’s address to the system 
running Observer. 
When redirecting the probe, you must specify the NAT outside IP 
address instead of the address that Observer puts in automatically. By 
default, Observer tries to use its local IP address, which the probe will 
not be able to find. Select “Redirect to a specified IP address” in the 
Redirecting Probe or Probe Instance dialog (Figure 86). 
Observer Console
Port
Any Probe
2
5
9
0
1
Port
25903
25901
25901
redirection request
request approved
connection established
connection request
e
n
n
e
n
o
p
n
