{"id":981,"date":"2018-11-12T15:55:39","date_gmt":"2018-11-12T08:55:39","guid":{"rendered":"https:\/\/www.whplus.com\/blog\/?p=981"},"modified":"2018-11-12T15:56:10","modified_gmt":"2018-11-12T08:56:10","slug":"how-to-disable-ipv6-on-centos-7","status":"publish","type":"post","link":"https:\/\/www.whplus.com\/blog\/2018\/11\/12\/how-to-disable-ipv6-on-centos-7.html","title":{"rendered":"How to disable IPv6 on CentOS 7"},"content":{"rendered":"

To verify if IPv6 is enabled or not, execute :<\/p>\n

# ifconfig -a | grep inet6
\n inet6 fe80::211:aff:fe6a:9de4 prefixlen 64 scopeid 0x20
\n inet6 ::1 prefixlen 128 scopeid 0x10[host]<\/code><\/p>\n

1. Disable IPv6 in kernel module (requires reboot)<\/strong>
\n1. Edit \/etc\/default\/grub and add ipv6.disable=1 in line GRUB_CMDLINE_LINUX, e.g.:<\/p>\n

# cat \/etc\/default\/grub
\nGRUB_TIMEOUT=5
\nGRUB_DEFAULT=saved
\nGRUB_DISABLE_SUBMENU=true
\nGRUB_TERMINAL_OUTPUT=\"console\"
\nGRUB_CMDLINE_LINUX=\"ipv6.disable=1 crashkernel=auto rhgb quiet\"
\nGRUB_DISABLE_RECOVERY=\"true\"<\/code><\/p>\n

2. Regenerate a GRUB configuration file and overwrite existing one:<\/p>\n

# grub2-mkconfig -o \/boot\/grub2\/grub.cfg<\/code><\/p>\n

3. Restart system and verify no line \u201cinet6\u201d in \u201cip addr show\u201d command output.<\/p>\n

# shutdown -r now<\/code><\/p>\n

# ip addr show | grep net6<\/code>
\n<\/p>\n

2. Disable IPv6 using sysctl settings (no reboot required)<\/strong><\/p>\n

1. Append below lines in \/etc\/sysctl.conf:<\/p>\n

net.ipv6.conf.all.disable_ipv6 = 1
\nnet.ipv6.conf.default.disable_ipv6 = 1<\/code><\/p>\n

2. To make the settings affective, execute :<\/p>\n

# sysctl -p<\/code><\/p>\n

NOTE : make sure the file \/etc\/ssh\/sshd_config contains the line AddressFamily inet to avoid breaking SSH Xforwarding if you are using the sysctl method<\/p>\n

3. Add the AddressFamily line to sshd_config :<\/p>\n

# vi \/etc\/ssh\/sshd_config<\/code><\/p>\n

....
\nAddressFamily inet
\n....<\/code><\/p>\n

Restart sshd for changes to get get effect :<\/p>\n

# systemctl restart sshd<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"

To verify if IPv6 is enabled or not, execute : # ifconfig -a | grep inet6 inet6 fe80::211:aff:fe6a:9de4 prefixlen 64 scopeid 0x20 inet6 ::1 prefixlen 128 scopeid 0x10[host] 1. Disable IPv6 in kernel module (requires reboot) 1. Edit \/etc\/default\/grub and add ipv6.disable=1 in line GRUB_CMDLINE_LINUX, e.g.: # cat \/etc\/default\/grub GRUB_TIMEOUT=5 GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT=”console” GRUB_CMDLINE_LINUX=”ipv6.disable=1 crashkernel=auto\u2026 Read More »<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-981","post","type-post","status-publish","format-standard","hentry","category-tutorial"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t