求问ubuntu上netstat出现tcp6，怎么回事

root@ubuntu:~# netstat -antp
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 7467/mysqld
tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN 6021/apache2
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 3672/nginx
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN 20861/vsftpd
tcp6 0 0 :::41958 :::* LISTEN 2924/java
tcp6 0 0 :::808 :::* LISTEN 2924/java
tcp6 0 0 127.0.0.1:6600 :::* LISTEN 30194/java
tcp6 0 0 :::60239 :::* LISTEN 30194/java
tcp6 0 0 127.0.0.1:6800 :::* LISTEN 2924/java
tcp6 0 0 :::22 :::* LISTEN 5137/sshd
tcp6 0 0 xxx.xxx.xxx.xxx:808 xxx.xxx.xxx.xxx:1121 TIME_WAIT -
tcp6 0 0 xxx.xxx.xxx.xxx:808 xxx.xxx.xxx.xxx:1082 ESTABLISHED 2924/java
tcp6 0 0 xxx.xxx.xxx.xxx:808 xxx.xxx.xxx.xxx:1122 TIME_WAIT -
tcp6 0 0 xxx.xxx.xxx.xxx:38947 :3306 ESTABLISHED 2924/java
tcp6 0 0 127.0.0.1:50639 127.0.0.1:46360 ESTABLISHED 30194/java

cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
address xxx.xxx.xxx.xxx
netmask xxx.xxx.xxx.xxx
gateway xxx.xxx.xxx.xxx

没发现tcp6设置，不知道tcp6怎么来得，对系统网络应用有没影响 不知道改哪儿 ==！

关闭ipv6就可以了，关闭方法：对于ubuntu 9.10及以上版本 ,可用以下方法：

  1. gksu gedit /etc/default/grub
  
将
     GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
  变为
     GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 quiet splash"
  2.  sudo update-grub