Why netstat not showing user name using "-p" option ?

Issue

• Netstat command not showing user in PID/program field.

# netstat -plant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address    Foreign Address        State           PID/Program name
tcp        0      0 xxxxxx:34427           xxxx:3268           ESTABLISHED           20430/sssd_be       
tcp        0      0 xxxxxx:22                  xxxx:44944         ESTABLISHED           20902/sshd      <<== No user

# netstat -plant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address  Foreign Address    State                 PID/Program nam       
tcp        0              0         xxxxxx:34427  xxxxxx:3268     ESTABLISHED   20430/sssd_be       
tcp        0              0         xxxxxx:22         xxxxxx:44944   ESTABLISHED  20902/sshd:  user1 [p    <<== user1