Verify firewall port assignments using netcat during WebSphere installation planning

During production installation of WebSphere, particularly where multiple node cluster is involved you will be overwhelmed with how many firewall changes need to be made across different vlans and open ports to make sure all the nodes, dmgr, websevers, databases, & ldap can communicate with each others without problems. Also at the same time make sure you only open the ports that are needed for security reasons. ACL firewall rules would become complex due to the different number of ports involved in WebSphere , by default on a single standalone node installation you can see below that there are about 18 ports or so involved,

Port Name Port
-------------------------------------------------------------------
BOOTSTRAP_ADDRESS 2809
SOAP_CONNECTOR_ADDRESS 8880
ORB_LISTENER_ADDRESS 9100
SAS_SSL_SERVERAUTH_LISTENER_ADDRESS 9401
CSIV2_SSL_SERVERAUTH_LISTENER_ADDRESS 9403
CSIV2_SSL_MUTUALAUTH_LISTENER_ADDRESS 9402
WC_adminhost 9060
WC_defaulthost 9080
DCS_UNICAST_ADDRESS 9353
WC_adminhost_secure 9043
WC_defaulthost_secure 9443
SIP_DEFAULTHOST 5060
SIP_DEFAULTHOST_SECURE 5061
SIB_ENDPOINT_ADDRESS 7276
SIB_ENDPOINT_SECURE_ADDRESS 7286
SIB_MQ_ENDPOINT_ADDRESS 5558
SIB_MQ_ENDPOINT_SECURE_ADDRESS 5578
IPC_CONNECTOR_ADDRESS 9633

So in order to make sure all firewall port assignments are proper before installing you need to connect to the listening port and check from the client. Since you don't have websphere actually installed those ports won't be listening and makes it difficult to check and verify. In order to verify you can use the netcat or nc utility in unix or linux. Basically with nc or netcat utility you can listen on any partucular port TCP or UDP and make connections from the client and verify that these port communication is opened through the firewall and resolve your network issues quickly.

Use netcat or nc to listen on port 9080,
(e.g) nc -l 9080

and then you can connect to the port from another client machine using nc or any other tool like telnet to see if it accepts connection,

(e.g) nc 192.169.1.1 9080
you can type on the stdin which will be transferred and displayed across each machine, form that you can know that ports are opened.

Also use nc to port scan as well, (e.g) nc -v -z 192.168.1.1 9080-9084
the output will showing what ports are opened as below,
hostname [192.168.1.1] 9080 (?) open