Disable IPv6 on Ubuntu
Method 1: sysctl
sudo gedit /etc/sysctl.conf
Append to end of file
# IPv6 disabled net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1
Save the file and close it. Restart sysctl with
sudo sysctl -p
Run
After that run $ cat /proc/sys/net/ipv6/conf/all/disable_ipv6
If it reports ‘1′ means you have disabled IPV6.
or
Check the output of ifconfig again and there should be no ipv6 address
ifconfig
eth0 Link encap:Ethernet HWaddr 08:00:27:5f:28:8b
inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1346 errors:0 dropped:0 overruns:0 frame:0
TX packets:965 errors:0 dropped:0 overruns:0 carrier:0
.....
If it does not work, then try rebooting the system and check ifconfig again.
Method 2: grub
sudo gedit /etc/default/grub
Look for the line containing “GRUB_CMDLINE_LINUX” and edit it as follows
GRUB_CMDLINE_LINUX="ipv6.disable=1"
The same can also be added to the value of the variable named “GRUB_CMDLINE_LINUX_DEFAULT” and either would work. Save the file, close it and regenerate the grub configuration
sudo update-grub2
Reboot. Now ipv6 should be disabled.