I started the vsftpd on Ubuntu 10.04, but can't connect to it.

The error says(FTP Client):

Status: Connecting to 124.205.xx.xx:21...
Error:  Connection timed out
Error:  Could not connect to server

I've checked the server status, and vsftpd is running:

$ ps ax | grep vsftpd
23646 ?        Ss     0:00 /usr/sbin/vsftpd
23650 pts/1    S+     0:00 grep --color=auto vsftpd

port 21 is under listening as well:

$ netstat -tlnp | grep 21
(No info could be read for "-p": geteuid()=1000 but you should be root.)
tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN      - 

I can connect to localhost:

$ ftp localhost
Connected to localhost.
220 (vsFTPd 2.2.2)
Name (localhost:jlee): 
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> 

Here is iptables output

$ sudo iptables -vL
Chain INPUT (policy ACCEPT 191 packets, 144K bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 124 packets, 28502 bytes)
 pkts bytes target     prot opt in     out     source               destination         

What's the problem here?