Post describes procedure to disable IPv6 on CentOS\/RHEL 7. There are 2 ways to do this :
\n1. Disable IPv6 in kernel module (requires reboot)
\n2. Disable IPv6 using sysctl settings (no reboot required)<\/p>\n
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]
\n1. Disable IPv6 in kernel module (requires reboot)<\/p>\n
1. 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”
\n2. Regenerate a GRUB configuration file and overwrite existing one:<\/p>\n
# grub2-mkconfig -o \/boot\/grub2\/grub.cfg
\n3. Restart system and verify no line \u201cinet6\u201d in \u201cip addr show\u201d command output.<\/p>\n
# shutdown -r now
\n# ip addr show | grep net6
\n2. Disable IPv6 using sysctl settings (no reboot required)<\/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
\nNOTE : To disable IPv6 on a single interface add below lines to \/etc\/sysctl.conf :
\nnet.ipv6.conf.[interface].disable_ipv6 = 1 ### put interface name here [interface]
\nnet.ipv6.conf.default.disable_ipv6 = 1
\n2. To make the settings affective, execute :<\/p>\n
# sysctl -p
\nNOTE : 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
\n3. Add the AddressFamily line to sshd_config :<\/p>\n
# vi \/etc\/ssh\/sshd_config
\n….
\nAddressFamily inet
\n….
\nRestart sshd for changes to get get effect :<\/p>\n
# systemctl restart sshd<\/p>\n","protected":false},"excerpt":{"rendered":"
Post describes procedure to disable IPv6 on CentOS\/RHEL 7. There are 2 ways to do this : 1. Disable IPv6 in kernel module (requires reboot) 2. Disable IPv6 using sysctl settings (no reboot required)<\/p>\n
To verify if IPv6 is enabled or not, execute :<\/p>\n
# ifconfig -a | grep inet6 inet6 fe80::211:aff:fe6a:9de4 prefixlen 64 scopeid […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[73],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6669"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6669"}],"version-history":[{"count":2,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6669\/revisions"}],"predecessor-version":[{"id":6671,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/6669\/revisions\/6671"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6669"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6669"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6669"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}