How to get only one public IPv6 address

Installing and Using OpenWrt Network and Wireless Configuration
1

I am using openwrt 24.10.4. My ISP provides dynamic IPv6 address.
For one of the client, I set static IPv4 address and IPv6-Suffix (hex) as below,

image
image967×478 23.9 KB

root@OpenWrt:~# cat /etc/config/dhcp

config dnsmasq
        option domainneeded '1'
        option localise_queries '1'
        option rebind_protection '0'
        option local '/lan/'
        option domain 'lan'
        option expandhosts '1'
        option cachesize '1000'
        option authoritative '1'
        option readethers '1'
        option leasefile '/tmp/dhcp.leases'
        option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
        option localservice '1'
        option ednspacket_max '1232'
        option confdir '/tmp/dnsmasq.d'
        list server '8.8.8.8'
        list server '1.1.1.1'

config dhcp 'lan'
        option interface 'lan'
        option start '200'
        option limit '50'
        option leasetime '12h'
        option dhcpv4 'server'
        option dhcpv6 'server'
        option ra 'server'
        list ra_flags 'managed-config'
        list ra_flags 'other-config'
        option leastime '12h'

config dhcp 'wan'
        option interface 'wan'
        option ignore '1'
        option start '100'
        option limit '150'
        option leasetime '12h'

config odhcpd 'odhcpd'
        option maindhcp '0'
        option leasefile '/tmp/hosts/odhcpd'
        option leasetrigger '/usr/sbin/odhcpd-update'
        option loglevel '4'

config host
        option name 'mypc'
        option ip '192.168.0.215'
        list mac 'F8:xx:xx:xx:xx:C1'
        option duid '00010001xxxxxxxxxxxxxxxxx0788f6'
        option hostid '65'

And on the client (windows 10),

PS C:\Users\xxx_x> ipconfig /all

Ethernet adapter Ethernet 2:

   Connection-specific DNS Suffix  . : lan
   Description . . . . . . . . . . . : ASIX USB to Gigabit Ethernet Family Adapter
   Physical Address. . . . . . . . . : F8-xx-xx-xx-xx-C1
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   IPv6 Address. . . . . . . . . . . : 2xxx:xxxx:51:xxxx::65(Preferred)
   Lease Obtained. . . . . . . . . . : Wednesday, October 15, 2025 1:21:34 PM
   Lease Expires . . . . . . . . . . : Thursday, October 16, 2025 1:21:34 AM
   IPv6 Address. . . . . . . . . . . : 2xxx:xxxx:51:xxxx::325(Preferred)
   Lease Obtained. . . . . . . . . . : Wednesday, October 15, 2025 12:17:45 PM
   Lease Expires . . . . . . . . . . : Thursday, October 16, 2025 12:17:45 AM
   IPv6 Address. . . . . . . . . . . : 2xxx:xxxx:51:xxxx:fae4:3bff:fee8:84c1(Preferred)
   IPv6 Address. . . . . . . . . . . : fd96:870e:ded0::65(Preferred)
   Lease Obtained. . . . . . . . . . : Wednesday, October 15, 2025 1:21:35 PM
   Lease Expires . . . . . . . . . . : Thursday, October 16, 2025 1:21:33 AM
   IPv6 Address. . . . . . . . . . . : fd96:870e:ded0:0:fae4:3bff:fee8:84c1(Preferred)
   Temporary IPv6 Address. . . . . . : 2xxx:xxxx:51:xxxx:f462:f015:8556:9a8c(Preferred)
   Temporary IPv6 Address. . . . . . : fd96:870e:ded0:0:f462:f015:8556:9a8c(Preferred)
   Link-local IPv6 Address . . . . . : fe80::fae4:3bff:fee8:84c1%17(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.0.215(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Wednesday, October 15, 2025 1:16:03 PM
   Lease Expires . . . . . . . . . . : Thursday, October 16, 2025 1:21:27 AM
   Default Gateway . . . . . . . . . : fe80::dea6:32ff:fe4a:cecb%17
                                       192.168.0.2
   DHCP Server . . . . . . . . . . . : 192.168.0.2
   DHCPv6 IAID . . . . . . . . . . . : 65xxxxxx63
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-xx-xx-xx-xx-xx-xx-xx-xx-xx-F6
   DNS Servers . . . . . . . . . . . : fd96:870e:ded0::1
                                       192.168.0.2
                                       fd96:870e:ded0::1
   NetBIOS over Tcpip. . . . . . . . : Enabled

As you can see there are many public IPv6 address starting 2xxx

And external systems see me as,

PS C:\Users\xxx_x> curl.exe -6 ifconfig.co
2xxx:xxxx:51:xxxx:f462:f015:8556:9a8c

Is there a way, I can get only the first public IPv6 address (2xxx:xxxx:51:xxxx::65)? So that external systems see that as my address?

2

This is a Windows question. If the OS allows you to turn off IPv6 Privacy, then yes.

(My other suggestion is against RFCs and Windows-specific, it will actually break connectivity for various other OSes.)

(Took a couple seconds on a standard web search.)

3

Search for "Windows IPv6 privacy extension"

1 Like