The port 512 will not be able to listen any incoming request if rexec service is disabled.
To check status of port:
bash-3.00# netstat -an | grep '512'
bash-3.00#
If its not listening then it will not return any output.
To check status of rexec service:
bash-3.00# svcs rexec
STATE STIME FMRI
disabled 9:49:41 svc:/network/rexec:default
bash-3.00#
Enable rexec service:
bash-3.00# svcadm enable rexec
bash-3.00# svcs rexec
STATE STIME FMRI
online 10:20:26 svc:/network/rexec:default
bash-3.00#
Now check the status of port:
bash-3.00# netstat -an | grep '512'
*.512 *.* 0 0 49152 0 LISTEN
192.168.1.21.512 192.168.1.11.1833 64511 0 49680 0 ESTABLISHED
*.512 *.* 0 0 49152 0 LISTEN