Ubuntu Isc-Dhcp 4.2.4 and disable IPv6 !

[CpServiceSPb .]

I have isc-dhcp-server installed at ubuntu 14.04 x64.

Its version is 4.2.4

 

I have fully disabled IPv6 at OS.

Also I have "-4" option for dhcp server startup.

 

But there is one IPv6 listened address by netstat -anupt.

Port is dyynamic.

 

 

What is this dynamically defined port intended for ?

 

And how is to fully disable IPv6 listening ?

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[Nicolas C.]

Le 16/03/2016 23:05, CpServiceSPb . a écrit :
> I have isc-dhcp-server installed at ubuntu 14.04 x64.
> Its version is 4.2.4
> I have fully disabled IPv6 at OS.
> Also I have "-4" option for dhcp server startup.
> But there is one IPv6 listened address by netstat -anupt.
> Port is dyynamic.
> What is this dynamically defined port intended for ?
> And how is to fully disable IPv6 listening ?

Hello,

What makes you think that this is caused by the DHCP server? Can you
give us the output of your "netstat" command? Is the dhcpd service
listening to an IPv6 address? Maybe a "ps -ef | grep dhcpd" will give us
a hint.

Try disabling IPv6 by adding "ipv6.disable=1" on the
GRUB_CMDLINE_LINUX_DEFAULT variable in the /etc/default/grub file, then
run "update-grub" and reboot. But there's little chance that the DHCP
server has anything to do with your problem because it is not dual-stack
: it can operate only for one protocol at the time (DHCPv4 *or* DHCPv6).

Have a nice day,
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[Marc Haber]

Hi,

On Thu, Mar 17, 2016 at 01:05:32AM +0300, CpServiceSPb . wrote:
> I have fully disabled IPv6 at OS.

Nosy question, I know. Why are you disabling a protocol that is
mandatory member of the IP stack, instead of using it?

Greetings
Marc

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[CpServiceSPb .]

Hi.

Output of netstat command made me think.

Let' s look:

 

tcp        0      0 127.0.0.1:5038          0.0.0.0:*               LISTEN      27158/asterisk
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      911/apache2
tcp        0      0 10.10.0.254:82          0.0.0.0:*               LISTEN      911/apache2
tcp        0      0 127.0.0.1:82            0.0.0.0:*               LISTEN      911/apache2
tcp        0      0 10.10.0.254:53          0.0.0.0:*               LISTEN      2167/named
tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      2167/named
tcp        0      0 10.10.0.254:5432        0.0.0.0:*               LISTEN      1635/postgres
tcp        0      0 127.0.0.1:5432          0.0.0.0:*               LISTEN      1635/postgres
tcp        0      0 127.0.0.1:953           0.0.0.0:*               LISTEN      2167/named
tcp        0      0 127.0.0.1:5432          127.0.0.1:59125         ESTABLISHED 27198/postgres: ast
tcp        0      0 127.0.0.1:59125         127.0.0.1:5432          ESTABLISHED 27158/asterisk
udp        0      0 0.0.0.0:5060            0.0.0.0:*                           27158/asterisk
udp        0      0 127.0.0.1:41958         127.0.0.1:41958         ESTABLISHED 1635/postgres
udp        0      0 0.0.0.0:40895           0.0.0.0:*                           12116/dhcpd
udp        0      0 10.10.0.254:53          0.0.0.0:*                           2167/named
udp        0      0 127.0.0.1:53            0.0.0.0:*                           2167/named
udp        0      0 0.0.0.0:67              0.0.0.0:*                           12116/dhcpd
udp   125440      0 0.0.0.0:68              0.0.0.0:*                           10681/charon
udp        0      0 10.10.0.254:123         0.0.0.0:*                           1290/ntpd
udp        0      0 127.0.0.1:123           0.0.0.0:*                           1290/ntpd
udp6       0      0 :::39873                :::*                                12116/dhcpd

 

 

I will try to change grubconf.

But I turned off IPv6 completely by sysctl.d.

 

With wishes of many good things.

2016-03-17 15:39 GMT+03:00 Nicolas C. <[hidden email]>:

Le 16/03/2016 23:05, CpServiceSPb . a écrit :

I have isc-dhcp-server installed at ubuntu 14.04 x64.
Its version is 4.2.4
I have fully disabled IPv6 at OS.
Also I have "-4" option for dhcp server startup.
But there is one IPv6 listened address by netstat -anupt.
Port is dyynamic.
What is this dynamically defined port intended for ?
And how is to fully disable IPv6 listening ?

Hello,

What makes you think that this is caused by the DHCP server? Can you give us the output of your "netstat" command? Is the dhcpd service listening to an IPv6 address? Maybe a "ps -ef | grep dhcpd" will give us a hint.

Try disabling IPv6 by adding "ipv6.disable=1" on the GRUB_CMDLINE_LINUX_DEFAULT variable in the /etc/default/grub file, then run "update-grub" and reboot. But there's little chance that the DHCP server has anything to do with your problem because it is not dual-stack : it can operate only for one protocol at the time (DHCPv4 *or* DHCPv6).

Have a nice day,

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dhcp-users mailing list
[hidden email]
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[Nicolas C.]

Le 17/03/2016 15:38, CpServiceSPb . a écrit :
> Hi. Output of netstat command made me think. Let' s look:
>
> [...]
>
> *udp6 0 0 :::39873 :::* 12116/dhcpd

According to this bug report, it's caused by the nsupdate capability of
dhcpd :

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=712503

It probably means that even though dhcpd is running in DHCPv4 mode, it
will perform DDNS (dynamic updates of DNS zones) with nsupdate either on
IPv4 or IPv6 protocol. So this is why you see dhcpd listening in IPv6.

My personal opinion is that's not really a bug : if the DHCP server has
an IPv6 connectivity with the DNS server, why not use IPv6 regardless of
the type of addresses that are being updated ?

Regards,

Nicolas
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[CpServiceSPb .]

Hi again.

Adding of GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1"

to /etc/default/grub allowed to avoid listening of ipv6 port by dhcpd.

 

Thanks.

 

With wishes of many good things.

2016-03-17 17:38 GMT+03:00 CpServiceSPb . <[hidden email]>:

Hi.

Output of netstat command made me think.

Let' s look:

 

tcp        0      0 127.0.0.1:5038          0.0.0.0:*               LISTEN      27158/asterisk
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      911/apache2
tcp        0      0 10.10.0.254:82          0.0.0.0:*               LISTEN      911/apache2
tcp        0      0 127.0.0.1:82            0.0.0.0:*               LISTEN      911/apache2
tcp        0      0 10.10.0.254:53          0.0.0.0:*               LISTEN      2167/named
tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      2167/named
tcp        0      0 10.10.0.254:5432        0.0.0.0:*               LISTEN      1635/postgres
tcp        0      0 127.0.0.1:5432          0.0.0.0:*               LISTEN      1635/postgres
tcp        0      0 127.0.0.1:953           0.0.0.0:*               LISTEN      2167/named
tcp        0      0 127.0.0.1:5432          127.0.0.1:59125         ESTABLISHED 27198/postgres: ast
tcp        0      0 127.0.0.1:59125         127.0.0.1:5432          ESTABLISHED 27158/asterisk
udp        0      0 0.0.0.0:5060            0.0.0.0:*                           27158/asterisk
udp        0      0 127.0.0.1:41958         127.0.0.1:41958         ESTABLISHED 1635/postgres
udp        0      0 0.0.0.0:40895           0.0.0.0:*                           12116/dhcpd
udp        0      0 10.10.0.254:53          0.0.0.0:*                           2167/named
udp        0      0 127.0.0.1:53            0.0.0.0:*                           2167/named
udp        0      0 0.0.0.0:67              0.0.0.0:*                           12116/dhcpd
udp   125440      0 0.0.0.0:68              0.0.0.0:*                           10681/charon
udp        0      0 10.10.0.254:123         0.0.0.0:*                           1290/ntpd
udp        0      0 127.0.0.1:123           0.0.0.0:*                           1290/ntpd
udp6       0      0 :::39873                :::*                                12116/dhcpd

 

 

I will try to change grubconf.

But I turned off IPv6 completely by sysctl.d.

 

With wishes of many good things.

2016-03-17 15:39 GMT+03:00 Nicolas C. <[hidden email]>:

Le 16/03/2016 23:05, CpServiceSPb . a écrit :

I have isc-dhcp-server installed at ubuntu 14.04 x64.
Its version is 4.2.4
I have fully disabled IPv6 at OS.
Also I have "-4" option for dhcp server startup.
But there is one IPv6 listened address by netstat -anupt.
Port is dyynamic.
What is this dynamically defined port intended for ?
And how is to fully disable IPv6 listening ?

Hello,

What makes you think that this is caused by the DHCP server? Can you give us the output of your "netstat" command? Is the dhcpd service listening to an IPv6 address? Maybe a "ps -ef | grep dhcpd" will give us a hint.

Try disabling IPv6 by adding "ipv6.disable=1" on the GRUB_CMDLINE_LINUX_DEFAULT variable in the /etc/default/grub file, then run "update-grub" and reboot. But there's little chance that the DHCP server has anything to do with your problem because it is not dual-stack : it can operate only for one protocol at the time (DHCPv4 *or* DHCPv6).

Have a nice day,

_______________________________________________
dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users