how to find which process bind a socket but not listen?

When I use nc to listen a port , it shows

nc -l -vv -p 21000retrying local 0.0.0.0:21000 : Address already in use Can't grab 0.0.0.0:21000 with bind

But I can not find which task occupy's this port with tools netstat / ss

netstat -an|grep 21000 

;nothing find

ss -a|grep 21000 

;nothing find

This port is occupied by my java program, the code is :

public class Test1 {        public static void main(String[] args) throws InterruptedException {        Socket s = new Socket();        try {            s.bind(new InetSocketAddress("127.0.0.1",21000));        } catch (IOException e) {            e.printStackTrace();        }        Thread.sleep(500000000000L);    }}

when I bind a socket ,but do not use it with connect or listen. I get into the /proc/[java task id]/fd , find the inode of this socket is "socket:[3073501]"but I can't find the inode or port even in /proc/net/tcp or /proc/net/tcp6

Is there any method to find the process which bind's the socket but does not listen or connect.

Thanks.

I see linux 3.10.0-327 source code. I think the content of the file /proc/net/tcp come from the net/ipv4/tcp_ipv4.c.

in tcp_proc_register method,

static void *tcp_get_idx(struct seq_file *seq, loff_t pos)      {        void *rc;        struct tcp_iter_state *st = seq->private;        st->state = TCP_SEQ_STATE_LISTENING;        rc        = listening_get_idx(seq, &pos);        if (!rc) {                st->state = TCP_SEQ_STATE_ESTABLISHED;                rc        = established_get_idx(seq, pos);        }        return rc;}

It shows only the socks in listening or established from tcp_hashinfo. But tcp_hashinfo has three struct

struct inet_bind_hashbucket     *bhash; struct inet_listen_hashbucket   listening_hash[INET_LHTABLE_SIZE];struct inet_ehash_bucket        *ehash;

bhash may be used for binding.But is does not export in /proc/net/tcp.