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Ipv6 hostname in dhclient.conf

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Anjali Krishna

Ipv6 hostname in dhclient.conf

I am using an embedded board with hostname "test_dut"[same under /etc/hostname]. I am testing ipv6 ans ipv4 using dhcpd on server side with - 6, - 4 options and client side I am using dhclient with - 6 and - 4 option for ipv6 and ipv4 respectively.

Both the cases Ip assignment is happening without any trouble. But in order to extend our application feature we are providing the information of the connected devices to the user such as mac id, ip, hostname/client name etc. In ipv4 these information are provided under dhcpd.leases file. In case of ipv6 I am not able to find the hostname (test_dut) under the dhcpd6.leases files

I tried with adding various options under dhclient.conf such as send host-name "test_dut" and edited the dhclient-script under /sbin and called set_hostname call under bound-renew-reboot section of ipv6. Still the server lease file is not updating the hostname for ipv6 . But hostname is updating for ipv4 connection.

How can I resolve this issue?

Regards,

Anjali

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Bill Shirley-2

Re: Ipv6 hostname in dhclient.conf

You can save your own variables in the leases file for non-static leases:
on commit { if static {# set is-static = " --> STATIC"; } else { set is-static = ""; set my_duid = option dhcp6.client-id; set my_duid_hex = pick-first-value(binary-to-ascii(16, 8, ":", option dhcp6.client-id), ""); set my_given_hostname = option fqdn.hostname; }}
Lease:
ia-na "mbl\022\000\001\000\001\025Yy\267lbm\207\267\370" { cltt 0 2020/07/12 12:45:07; iaaddr 2001:xxxx:yyyy:40:50f7::ee { binding state active; preferred-life 9000; max-life 14400; ends 0 2020/07/12 16:45:07; set ddns-rev-name = "<redacted>"; set ddns-dhcid = "\000\002\001\320F0\342\231\334\262\211\351u\023\260\207\200\240%\230\004ZD\035\370\221f\367E\225\245e\234\2154"; set ddns-fwd-name = "Karen-PC.example.com"; set my_MAC = "6c:62:6d:87:b7:f8"; set my_given_hostname = "Karen-PC"; set my_duid_hex = "0:1:0:1:15:59:79:b7:6c:62:6d:87:b7:f8"; set my_duid = "\000\001\000\001\025Yy\267lbm\207\267\370"; set member_of = "Microsoft"; set pool_type = "Microsoft"; }}
Hope this helps,
Bill

On 7/27/2020 8:04 AM, Anjali Krishna wrote:

Hi

I am using an embedded board with hostname "test_dut"[same under /etc/hostname]. I am testing ipv6 ans ipv4 using dhcpd on server side with - 6, - 4 options and client side I am using dhclient with - 6 and - 4 option for ipv6 and ipv4 respectively.

Both the cases Ip assignment is happening without any trouble. But in order to extend our application feature we are providing the information of the connected devices to the user such as mac id, ip, hostname/client name etc. In ipv4 these information are provided under dhcpd.leases file. In case of ipv6 I am not able to find the hostname (test_dut) under the dhcpd6.leases files

I tried with adding various options under dhclient.conf such as send host-name "test_dut" and edited the dhclient-script under /sbin and called set_hostname call under bound-renew-reboot section of ipv6. Still the server lease file is not updating the hostname for ipv6 . But hostname is updating for ipv4 connection.

How can I resolve this issue?

Regards,

Anjali
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

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Anjali Krishna

Re: Ipv6 hostname in dhclient.conf

Hi Bill Shirley,

Thank you for the reply

The code snippet which you have shared I tried under dhcpd.conf

The my_duid_hex and my_duid variables are updating with the values

I tried with "send fqdn.hostname "test_dut" " in dhclient.conf file.

But the hostname is not still updating in the lease file

What am I missing in client side?

On Tue, 28 Jul 2020, 1:49 am Bill Shirley, <[hidden email]> wrote:

You can save your own variables in the leases file for non-static leases:
on commit { if static {# set is-static = " --> STATIC"; } else { set is-static = ""; set my_duid = option dhcp6.client-id; set my_duid_hex = pick-first-value(binary-to-ascii(16, 8, ":", option dhcp6.client-id), ""); set my_given_hostname = option fqdn.hostname; }}
Lease:
ia-na "mbl\022\000\001\000\001\025Yy\267lbm\207\267\370" { cltt 0 2020/07/12 12:45:07; iaaddr 2001:xxxx:yyyy:40:50f7::ee { binding state active; preferred-life 9000; max-life 14400; ends 0 2020/07/12 16:45:07; set ddns-rev-name = "<redacted>"; set ddns-dhcid = "\000\002\001\320F0\342\231\334\262\211\351u\023\260\207\200\240%\230\004ZD\035\370\221f\367E\225\245e\234\2154"; set ddns-fwd-name = "Karen-PC.example.com"; set my_MAC = "6c:62:6d:87:b7:f8"; set my_given_hostname = "Karen-PC"; set my_duid_hex = "0:1:0:1:15:59:79:b7:6c:62:6d:87:b7:f8"; set my_duid = "\000\001\000\001\025Yy\267lbm\207\267\370"; set member_of = "Microsoft"; set pool_type = "Microsoft"; }}
Hope this helps,
Bill

On 7/27/2020 8:04 AM, Anjali Krishna wrote:
Hi

I am using an embedded board with hostname "test_dut"[same under /etc/hostname]. I am testing ipv6 ans ipv4 using dhcpd on server side with - 6, - 4 options and client side I am using dhclient with - 6 and - 4 option for ipv6 and ipv4 respectively.

Both the cases Ip assignment is happening without any trouble. But in order to extend our application feature we are providing the information of the connected devices to the user such as mac id, ip, hostname/client name etc. In ipv4 these information are provided under dhcpd.leases file. In case of ipv6 I am not able to find the hostname (test_dut) under the dhcpd6.leases files

I tried with adding various options under dhclient.conf such as send host-name "test_dut" and edited the dhclient-script under /sbin and called set_hostname call under bound-renew-reboot section of ipv6. Still the server lease file is not updating the hostname for ipv6 . But hostname is updating for ipv4 connection.

How can I resolve this issue?

Regards,

Anjali
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

dhcp-users mailing list
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https://lists.isc.org/mailman/listinfo/dhcp-users
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Bill Shirley-2

Re: Ipv6 hostname in dhclient.conf

On the server, did you implement?:
set my_given_hostname = option fqdn.hostname;
It should be in the lease file even if it is blank.

Run tcpdump on the dhcp server to see exactly what is sent/received:
tcpdump -vv -e -n -i eth0 portrange 67-68For IPv6.
tcpdump -X -l -vv -e -n -i eth0 portrange 546-547
Bill

On 7/28/2020 4:27 AM, Anjali Krishna wrote:

Hi Bill Shirley,

Thank you for the reply

The code snippet which you have shared I tried under dhcpd.conf

The my_duid_hex and my_duid variables are updating with the values

I tried with "send fqdn.hostname "test_dut" " in dhclient.conf file.

But the hostname is not still updating in the lease file

What am I missing in client side?
On Tue, 28 Jul 2020, 1:49 am Bill Shirley, <[hidden email]> wrote:
You can save your own variables in the leases file for non-static leases:
on commit { if static {# set is-static = " --> STATIC"; } else { set is-static = ""; set my_duid = option dhcp6.client-id; set my_duid_hex = pick-first-value(binary-to-ascii(16, 8, ":", option dhcp6.client-id), ""); set my_given_hostname = option fqdn.hostname; }}
Lease:
ia-na "mbl\022\000\001\000\001\025Yy\267lbm\207\267\370" { cltt 0 2020/07/12 12:45:07; iaaddr 2001:xxxx:yyyy:40:50f7::ee { binding state active; preferred-life 9000; max-life 14400; ends 0 2020/07/12 16:45:07; set ddns-rev-name = "<redacted>"; set ddns-dhcid = "\000\002\001\320F0\342\231\334\262\211\351u\023\260\207\200\240%\230\004ZD\035\370\221f\367E\225\245e\234\2154"; set ddns-fwd-name = "Karen-PC.example.com"; set my_MAC = "6c:62:6d:87:b7:f8"; set my_given_hostname = "Karen-PC"; set my_duid_hex = "0:1:0:1:15:59:79:b7:6c:62:6d:87:b7:f8"; set my_duid = "\000\001\000\001\025Yy\267lbm\207\267\370"; set member_of = "Microsoft"; set pool_type = "Microsoft"; }}
Hope this helps,
Bill

On 7/27/2020 8:04 AM, Anjali Krishna wrote:
Hi

I am using an embedded board with hostname "test_dut"[same under /etc/hostname]. I am testing ipv6 ans ipv4 using dhcpd on server side with - 6, - 4 options and client side I am using dhclient with - 6 and - 4 option for ipv6 and ipv4 respectively.

Both the cases Ip assignment is happening without any trouble. But in order to extend our application feature we are providing the information of the connected devices to the user such as mac id, ip, hostname/client name etc. In ipv4 these information are provided under dhcpd.leases file. In case of ipv6 I am not able to find the hostname (test_dut) under the dhcpd6.leases files

I tried with adding various options under dhclient.conf such as send host-name "test_dut" and edited the dhclient-script under /sbin and called set_hostname call under bound-renew-reboot section of ipv6. Still the server lease file is not updating the hostname for ipv6 . But hostname is updating for ipv4 connection.

How can I resolve this issue?

Regards,

Anjali
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

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Anjali Krishna

Re: Ipv6 hostname in dhclient.conf

Hi Bill,

Thank you for the support

The hostname is updating in the lease file after updating this line in dhclient

send fqdn.fqdn "hostname.example.com."

The dot after the com was missing after this change it did work.

On Tue, 28 Jul 2020, 4:28 pm Bill Shirley, <[hidden email]> wrote:

On the server, did you implement?:
set my_given_hostname = option fqdn.hostname;
It should be in the lease file even if it is blank.

Run tcpdump on the dhcp server to see exactly what is sent/received:
tcpdump -vv -e -n -i eth0 portrange 67-68For IPv6.
tcpdump -X -l -vv -e -n -i eth0 portrange 546-547
Bill

On 7/28/2020 4:27 AM, Anjali Krishna wrote:
Hi Bill Shirley,

Thank you for the reply

The code snippet which you have shared I tried under dhcpd.conf

The my_duid_hex and my_duid variables are updating with the values

I tried with "send fqdn.hostname "test_dut" " in dhclient.conf file.

But the hostname is not still updating in the lease file

What am I missing in client side?
On Tue, 28 Jul 2020, 1:49 am Bill Shirley, <[hidden email]> wrote:
You can save your own variables in the leases file for non-static leases:
on commit { if static {# set is-static = " --> STATIC"; } else { set is-static = ""; set my_duid = option dhcp6.client-id; set my_duid_hex = pick-first-value(binary-to-ascii(16, 8, ":", option dhcp6.client-id), ""); set my_given_hostname = option fqdn.hostname; }}
Lease:
ia-na "mbl\022\000\001\000\001\025Yy\267lbm\207\267\370" { cltt 0 2020/07/12 12:45:07; iaaddr 2001:xxxx:yyyy:40:50f7::ee { binding state active; preferred-life 9000; max-life 14400; ends 0 2020/07/12 16:45:07; set ddns-rev-name = "<redacted>"; set ddns-dhcid = "\000\002\001\320F0\342\231\334\262\211\351u\023\260\207\200\240%\230\004ZD\035\370\221f\367E\225\245e\234\2154"; set ddns-fwd-name = "Karen-PC.example.com"; set my_MAC = "6c:62:6d:87:b7:f8"; set my_given_hostname = "Karen-PC"; set my_duid_hex = "0:1:0:1:15:59:79:b7:6c:62:6d:87:b7:f8"; set my_duid = "\000\001\000\001\025Yy\267lbm\207\267\370"; set member_of = "Microsoft"; set pool_type = "Microsoft"; }}
Hope this helps,
Bill

On 7/27/2020 8:04 AM, Anjali Krishna wrote:
Hi

I am using an embedded board with hostname "test_dut"[same under /etc/hostname]. I am testing ipv6 ans ipv4 using dhcpd on server side with - 6, - 4 options and client side I am using dhclient with - 6 and - 4 option for ipv6 and ipv4 respectively.

Both the cases Ip assignment is happening without any trouble. But in order to extend our application feature we are providing the information of the connected devices to the user such as mac id, ip, hostname/client name etc. In ipv4 these information are provided under dhcpd.leases file. In case of ipv6 I am not able to find the hostname (test_dut) under the dhcpd6.leases files

I tried with adding various options under dhclient.conf such as send host-name "test_dut" and edited the dhclient-script under /sbin and called set_hostname call under bound-renew-reboot section of ipv6. Still the server lease file is not updating the hostname for ipv6 . But hostname is updating for ipv4 connection.

How can I resolve this issue?

Regards,

Anjali
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

dhcp-users mailing list
[hidden email]
https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information.

dhcp-users mailing list
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_______________________________________________
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Anjali Krishna

Re: Ipv6 namservers and dhclient-script

In reply to this post by Anjali Krishna

Hi,

I am behind the dhclient-script for past the two days which updates the /etc/resolv.conf. Let me explain the scenario

The dhcp server is sending the ipv6 dhcp nams server to the client. The dhcp server has the name server in the sever conf file as below

subnet6 2001:470:108:4::2/64 {

...........…......................................

option dhcp6.name-servers 2001:470:108:4::10;

..................................................

}

The dhclient has "dhcp6.name-servers" string under request in dhclient.conf

In dhclient-script under dhcpv6 section the name servers are being updated in /etc/resolv.conf. The default behaviour of the script is to write the new name-servers to the resolv.conf file overwriting the old contents. The overwriting of this file is not acceptable since it is having nameserver IP updated or used by LTE, ethernet in my testing environment.

So I tried to tweak the script a bit by removing the mv command and appending the dhcp6 name servers using echo command directly to resolv.conf than writing to a temp file.

Within the make_resolv_conf function as the last statement I displayed the content of resolv.conf. I executed the dhclient with - 6 and - v enabled. The client fetched the the new ip and print shows the nameserver is appended(cat /etc/resolv.conf)

By default the /etc/resolv.conf content was

nameserver 8.8.8.8

nameserver 8.8.4.4

The print (cat /etc/resolv.conf) showed the content as

namserver 2001:470:108:4::10

nameserver 8.8.8.8

nameserver 8.8.4.4

Once the dhclient stops successfully I opened the resolv.conf and the new servers were missing. It is having default IPs. What could be the reason for this behaviour.?

Who is refreshing the /etc/resolv.conf. I checked the dhclient-script but couldn't find any clue for this.

To confirm no other process updates the file, I killed the LTE process but the result was same. Other than dhclient-script how the resolv.conf is getting overwritten all the time? What am I missing?

Any help would be much appreciated

On Mon, 27 Jul 2020, 5:34 pm Anjali Krishna, <[hidden email]> wrote:

Hi

I am using an embedded board with hostname "test_dut"[same under /etc/hostname]. I am testing ipv6 ans ipv4 using dhcpd on server side with - 6, - 4 options and client side I am using dhclient with - 6 and - 4 option for ipv6 and ipv4 respectively.
Both the cases Ip assignment is happening without any trouble. But in order to extend our application feature we are providing the information of the connected devices to the user such as mac id, ip, hostname/client name etc. In ipv4 these information are provided under dhcpd.leases file. In case of ipv6 I am not able to find the hostname (test_dut) under the dhcpd6.leases files

I tried with adding various options under dhclient.conf such as send host-name "test_dut" and edited the dhclient-script under /sbin and called set_hostname call under bound-renew-reboot section of ipv6. Still the server lease file is not updating the hostname for ipv6 . But hostname is updating for ipv4 connection.

How can I resolve this issue?

Regards,
Anjali