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ntp using ipv6 address instead of ipv4


Properly configuring symmetric active NTP?Flow of ipv4 over ipv6 tunnelResolving IPv4 address from DNS using the IPv6 address of a host (bind9)NTP Servers not Sync with other machinesAdd IPv6 address to existing IPv4 interface not workingMapping IPv6 to IPv4 addressesChrony does not want to synchronizeNTP pool provide only IPv4 records?Change the listening address to IPv4 from IPv6Time drifting after NTP is configured






.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








1















I have a laptop running a version of Linux ( 3.12 ). I have ntpd installed and configured to sync with time.google.com. The problem I am having is if I am plugged into a network that only provides an IPV4 address, ntp's dns is using the ipv6 address:



 root@Node00b01973d6cc:~# ntpq -pn 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 7 64 1 0.000 0.000 0.002
ff0e::101 .MCST. 16 M - 64 0 0.000 0.000 0.002
2001:4860:4806: .INIT. 16 u - 64 0 0.000 0.000 0.000


Now, if I force ntpd to use only ipv4 DNS with the -4 option, everything works fine



root@Node00b01973d6cc:~# ntpq -pn 172.16.17.111 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 60 64 1 0.000 0.000 0.002
216.239.35.12 .GOOG. 1 u 57 64 1 29.278 341.883 0.002


But I don't want to do this because if I go to a network that only gives ipv6 addresses this will fail. Is there a way to configure ntp to only use ipv4 ( or ipv6 ) if my interface actually has an ip address in that family?



The version of ntpd is 4.2.8p12. This is the ntp.conf file:



tinker panic 0 

driftfile /usr/local/etc/ntp.drift
disable auth

# Update the realtime clock and override its default
# stratum of 0.
server time.google.com prefer #Real Time Clock
server 127.127.1.0 #Real Time Clock
server 127.127.1.0 #Real Time Clock
fudge 127.127.1.0 stratum 10
broadcast ff0e::101 iburst ttl 7


I have figured out the root cause of why this started to happen. I recently disabled ipv6 forwarding on my system. Once I turn ipv6 forwarding back on, ntp starts using the ipv4 address as I would expect.



Why would turning on ipv6 forwarding do this?



By default the system boots with ipv6 forwarding disabled. To turn it on, in one of the boot scripts I have the line:



sysctl -w net.ipv6.conf.all.forwarding=1









share|improve this question
























  • I don't know. I notice on my Fedora 29 system that getent hosts time.google.com returns IPv6 only, even though I do not have ipv6 access, but getent ahosts time.google.com returns all results in the correct preference order. So I tried enabling ipv6 forwarding at runtime, both in conf.all and in conf.wlp2s0, but it did not change the result of getent hosts time.google.com

    – sourcejedi
    2 days ago












  • To gain a working configuration, I guess you could try an ugly hack with two separate server lines. server -4 time.google.com and server -6 time.google.com.

    – sourcejedi
    2 days ago


















1















I have a laptop running a version of Linux ( 3.12 ). I have ntpd installed and configured to sync with time.google.com. The problem I am having is if I am plugged into a network that only provides an IPV4 address, ntp's dns is using the ipv6 address:



 root@Node00b01973d6cc:~# ntpq -pn 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 7 64 1 0.000 0.000 0.002
ff0e::101 .MCST. 16 M - 64 0 0.000 0.000 0.002
2001:4860:4806: .INIT. 16 u - 64 0 0.000 0.000 0.000


Now, if I force ntpd to use only ipv4 DNS with the -4 option, everything works fine



root@Node00b01973d6cc:~# ntpq -pn 172.16.17.111 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 60 64 1 0.000 0.000 0.002
216.239.35.12 .GOOG. 1 u 57 64 1 29.278 341.883 0.002


But I don't want to do this because if I go to a network that only gives ipv6 addresses this will fail. Is there a way to configure ntp to only use ipv4 ( or ipv6 ) if my interface actually has an ip address in that family?



The version of ntpd is 4.2.8p12. This is the ntp.conf file:



tinker panic 0 

driftfile /usr/local/etc/ntp.drift
disable auth

# Update the realtime clock and override its default
# stratum of 0.
server time.google.com prefer #Real Time Clock
server 127.127.1.0 #Real Time Clock
server 127.127.1.0 #Real Time Clock
fudge 127.127.1.0 stratum 10
broadcast ff0e::101 iburst ttl 7


I have figured out the root cause of why this started to happen. I recently disabled ipv6 forwarding on my system. Once I turn ipv6 forwarding back on, ntp starts using the ipv4 address as I would expect.



Why would turning on ipv6 forwarding do this?



By default the system boots with ipv6 forwarding disabled. To turn it on, in one of the boot scripts I have the line:



sysctl -w net.ipv6.conf.all.forwarding=1









share|improve this question
























  • I don't know. I notice on my Fedora 29 system that getent hosts time.google.com returns IPv6 only, even though I do not have ipv6 access, but getent ahosts time.google.com returns all results in the correct preference order. So I tried enabling ipv6 forwarding at runtime, both in conf.all and in conf.wlp2s0, but it did not change the result of getent hosts time.google.com

    – sourcejedi
    2 days ago












  • To gain a working configuration, I guess you could try an ugly hack with two separate server lines. server -4 time.google.com and server -6 time.google.com.

    – sourcejedi
    2 days ago














1












1








1








I have a laptop running a version of Linux ( 3.12 ). I have ntpd installed and configured to sync with time.google.com. The problem I am having is if I am plugged into a network that only provides an IPV4 address, ntp's dns is using the ipv6 address:



 root@Node00b01973d6cc:~# ntpq -pn 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 7 64 1 0.000 0.000 0.002
ff0e::101 .MCST. 16 M - 64 0 0.000 0.000 0.002
2001:4860:4806: .INIT. 16 u - 64 0 0.000 0.000 0.000


Now, if I force ntpd to use only ipv4 DNS with the -4 option, everything works fine



root@Node00b01973d6cc:~# ntpq -pn 172.16.17.111 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 60 64 1 0.000 0.000 0.002
216.239.35.12 .GOOG. 1 u 57 64 1 29.278 341.883 0.002


But I don't want to do this because if I go to a network that only gives ipv6 addresses this will fail. Is there a way to configure ntp to only use ipv4 ( or ipv6 ) if my interface actually has an ip address in that family?



The version of ntpd is 4.2.8p12. This is the ntp.conf file:



tinker panic 0 

driftfile /usr/local/etc/ntp.drift
disable auth

# Update the realtime clock and override its default
# stratum of 0.
server time.google.com prefer #Real Time Clock
server 127.127.1.0 #Real Time Clock
server 127.127.1.0 #Real Time Clock
fudge 127.127.1.0 stratum 10
broadcast ff0e::101 iburst ttl 7


I have figured out the root cause of why this started to happen. I recently disabled ipv6 forwarding on my system. Once I turn ipv6 forwarding back on, ntp starts using the ipv4 address as I would expect.



Why would turning on ipv6 forwarding do this?



By default the system boots with ipv6 forwarding disabled. To turn it on, in one of the boot scripts I have the line:



sysctl -w net.ipv6.conf.all.forwarding=1









share|improve this question
















I have a laptop running a version of Linux ( 3.12 ). I have ntpd installed and configured to sync with time.google.com. The problem I am having is if I am plugged into a network that only provides an IPV4 address, ntp's dns is using the ipv6 address:



 root@Node00b01973d6cc:~# ntpq -pn 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 7 64 1 0.000 0.000 0.002
ff0e::101 .MCST. 16 M - 64 0 0.000 0.000 0.002
2001:4860:4806: .INIT. 16 u - 64 0 0.000 0.000 0.000


Now, if I force ntpd to use only ipv4 DNS with the -4 option, everything works fine



root@Node00b01973d6cc:~# ntpq -pn 172.16.17.111 
remote refid st t when poll reach delay offset jitter
==============================================================================
127.127.1.0 .LOCL. 10 l 60 64 1 0.000 0.000 0.002
216.239.35.12 .GOOG. 1 u 57 64 1 29.278 341.883 0.002


But I don't want to do this because if I go to a network that only gives ipv6 addresses this will fail. Is there a way to configure ntp to only use ipv4 ( or ipv6 ) if my interface actually has an ip address in that family?



The version of ntpd is 4.2.8p12. This is the ntp.conf file:



tinker panic 0 

driftfile /usr/local/etc/ntp.drift
disable auth

# Update the realtime clock and override its default
# stratum of 0.
server time.google.com prefer #Real Time Clock
server 127.127.1.0 #Real Time Clock
server 127.127.1.0 #Real Time Clock
fudge 127.127.1.0 stratum 10
broadcast ff0e::101 iburst ttl 7


I have figured out the root cause of why this started to happen. I recently disabled ipv6 forwarding on my system. Once I turn ipv6 forwarding back on, ntp starts using the ipv4 address as I would expect.



Why would turning on ipv6 forwarding do this?



By default the system boots with ipv6 forwarding disabled. To turn it on, in one of the boot scripts I have the line:



sysctl -w net.ipv6.conf.all.forwarding=1






dns ipv6 ntp ipv4






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Mar 30 at 15:05







tpotter01

















asked Mar 28 at 12:25









tpotter01tpotter01

62




62












  • I don't know. I notice on my Fedora 29 system that getent hosts time.google.com returns IPv6 only, even though I do not have ipv6 access, but getent ahosts time.google.com returns all results in the correct preference order. So I tried enabling ipv6 forwarding at runtime, both in conf.all and in conf.wlp2s0, but it did not change the result of getent hosts time.google.com

    – sourcejedi
    2 days ago












  • To gain a working configuration, I guess you could try an ugly hack with two separate server lines. server -4 time.google.com and server -6 time.google.com.

    – sourcejedi
    2 days ago


















  • I don't know. I notice on my Fedora 29 system that getent hosts time.google.com returns IPv6 only, even though I do not have ipv6 access, but getent ahosts time.google.com returns all results in the correct preference order. So I tried enabling ipv6 forwarding at runtime, both in conf.all and in conf.wlp2s0, but it did not change the result of getent hosts time.google.com

    – sourcejedi
    2 days ago












  • To gain a working configuration, I guess you could try an ugly hack with two separate server lines. server -4 time.google.com and server -6 time.google.com.

    – sourcejedi
    2 days ago

















I don't know. I notice on my Fedora 29 system that getent hosts time.google.com returns IPv6 only, even though I do not have ipv6 access, but getent ahosts time.google.com returns all results in the correct preference order. So I tried enabling ipv6 forwarding at runtime, both in conf.all and in conf.wlp2s0, but it did not change the result of getent hosts time.google.com

– sourcejedi
2 days ago






I don't know. I notice on my Fedora 29 system that getent hosts time.google.com returns IPv6 only, even though I do not have ipv6 access, but getent ahosts time.google.com returns all results in the correct preference order. So I tried enabling ipv6 forwarding at runtime, both in conf.all and in conf.wlp2s0, but it did not change the result of getent hosts time.google.com

– sourcejedi
2 days ago














To gain a working configuration, I guess you could try an ugly hack with two separate server lines. server -4 time.google.com and server -6 time.google.com.

– sourcejedi
2 days ago






To gain a working configuration, I guess you could try an ugly hack with two separate server lines. server -4 time.google.com and server -6 time.google.com.

– sourcejedi
2 days ago











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