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20 votes
Accepted

Can clients learn their time zone on a network configured using RA?

Stateless address autoconfiguration doesn't provide any way to transmit time zone information, but DHCPv6 does. The DHCPv4 options 100 and 101 correspond to the DHCPv6 options 41 and 42 respectively. ...
Michael Hampton's user avatar
18 votes
Accepted

IPv4 To IPv6 Migration Advice

This seemed like overkill to me, we already wont come close to filling the single /64 but this might be my IPv4 mindset confusing me. Stop counting hosts, that's IPv4 thinking. Subnets come in one ...
John Mahowald's user avatar
9 votes
Accepted

Why is a /128 IPv6 address assigned via DHCPv6 in Ubuntu?

Yes, this is the normal behaviour. DHCPv6 servers give out addresses (with the IA_NA option) but don't tell the client anything about the subnet. The client therefore just configures the separate ...
Sander Steffann's user avatar
9 votes
Accepted

How can IPv6 clients find servers such as NTP, SIP

DNS can be taken care of by router advertisements, but as for all other options, you're basically stuck with DHCP. However, a stateless DHCPv6 server is one valid deployment, where the DHCPv6 server ...
Stuggi's user avatar
  • 3,576
9 votes

IPv4 To IPv6 Migration Advice

First: get that /48. For security and manageability not putting everything in a single broadcast domain (VLAN) is good practice. Second: for servers just configure the addresses statically. You can ...
Sander Steffann's user avatar
8 votes
Accepted

How to get a proper prefix length from DHCPv6 server?

As per the DHCPd documentation: In a properly functioning system the client should use a prefix length of 128 and get any on-link information from the RAs from a router. Since you are using two ...
Tommiie's user avatar
  • 5,685
6 votes

How do I enable IPv6 on Fedora 28 on Amazon EC2

This happens because the current cloud-init version (I tested with 17.1) does not regenerate network settings on every boot. Network settings are only generated on the first instance boot. You can ...
bennofs's user avatar
  • 161
6 votes

How can DHCPv6 server allocate fixed IPv6 addresses to clients if it's not allowed to interpret DUID?

You're reading it wrong. They're allowed to compare if DUID's are equal to a stored value. They should not try to interpret the content of it in any other way, e.g. to try to retrieve the MAC address ...
vidarlo's user avatar
  • 9,729
4 votes
Accepted

Run script when ipv6 address changes

You can use the ip -6 monitor address command to feed an event loop. This could look like this in shell. Probably an other language than shell might be easier: ip -6 monitor | while read word1 ...
A.B's user avatar
  • 12.9k
4 votes
Accepted

How can DHCPv6 server allocate fixed IPv6 addresses to clients if it's not allowed to interpret DUID?

A client should not change its DUID between reboots, so once you have assigned a specific IPv6 address to a client it should get the configured address every time. The advantage of the DUID is that it ...
Sander Steffann's user avatar
4 votes

IPv4 To IPv6 Migration Advice

Alternatively I have the option to ask the ISP for a /48, should I do that and advertise a single /64 for local clients to get connectivity and different /64 for static servers? Absolutely ask ...
Kevin Keane's user avatar
3 votes

IPv6 on Amazon VPC: missing default route in Ubuntu

Your routing table does not look correct. This line looks very wrong: default dev eth0 metric 1024 This line says that the entire internet is connected directly to your eth0 interface without ...
kasperd's user avatar
  • 30.8k
3 votes

ipv6: low level technical explanation of Stateless address autoconfiguration

Link-local addresses are addresses that can only be used on the local network, and every network uses the same addresses. You might compare them to the 169.254.0.0/16 APIPA addresses in IPv4 with the ...
Sander Steffann's user avatar
2 votes

DHCPv6 not working when UFW is enabled (Ubuntu 16.04 LTS)

I see an existing rule for a DHCP client: # allow dhcp client to work -A ufw6-before-input -p udp -s fe80::/10 --sport 547 -d fe80::/10 --dport 546 -j ACCEPT I think you need to reverse the source/...
tjvr's user avatar
  • 121
2 votes
Accepted

IPv6 on Amazon VPC: missing default route in Ubuntu

It turned out I missed a step in the migration guide. When enabling IPv6 on an existing VPC some things, like route tables and security groups, have to be manually updated if you've made ...
Martijn Heemels's user avatar
2 votes
Accepted

Is it common for DHCPv6 and RA to provide IPv6 addr in the same subnet?

It's common not to hand out addresses with DHCPv6 at all. In the cases where DHCPv6 is used to configure addresses the A-flag is usually turned off. But what you describe is possible too. I have seen ...
Sander Steffann's user avatar
2 votes

rfc 6939 support for dhcpv6 relay

If you have a pretty flat network without DHCPv6 relay just look at dhcpy6d (https://dhcpy6d.ifw-dresden.de). It takes MAC addresses from neighbor cache and not from link local address so they are ...
user388449's user avatar
2 votes
Accepted

How to disable IPv6 dhcpstaticipcoexistence on Server 2019

Try test command from PowerShell Set-NetIPInterface -InterfaceIndex 3 -addressFamily IPv6 -dhcp Disabled
Spanner's user avatar
  • 36
2 votes
Accepted

Simple stateful DHCPv6 using ISC DHCP and RADVD. Doesnt work?

Apparently enp1s0 prefix length should be: 64 is just a warning and not the cause of the issue. In my particular case the reason this wasn't working was that the client wasn't accepting RAs. To accept ...
carloslockward's user avatar
2 votes
Accepted

Is SLAAC generation affected by non 64 bit size network prefix?

In https://datatracker.ietf.org/doc/html/rfc4862#section-5.5.3 it is specified that: If the sum of the prefix length and interface identifier length does not equal 128 bits, the Prefix Information ...
Sander Steffann's user avatar
1 vote

Netplan- How to configure a static IPv6-address and SLACC

Yes, It is possible. You should edit the netpplan configuration file (etc/netplan/config.yaml) and here is a example to achieve your goal. dhcp4: no dhcp6: no addresses: - "YOUR_IPV6&...
AmirD12's user avatar
  • 44
1 vote

How does Windows DHCPv6 server prevent conflicts with other DHCPv6 servers?

Assign different scopes to each DHCP server, each being its own /64. Say for example 2001:db8:8721:d001::/64 and 2001:db8:8721:d002::/64. Overlap is impossible which each has their own space out of ...
John Mahowald's user avatar
1 vote
Accepted

systemd-networkd not launching DHCPv6 client

Ok, it seems WithoutRA=solicit is the setting needed under [DHCPv6]. I might file an issue with the docs, as this seems contradictory to statement in the [Network] section.
Coops's user avatar
  • 6,125
1 vote
Accepted

How to configure DHCPv6 in Proxmox without bridge?

Turns out I was doing some things a bit overcomplicated, now I have managed to answer the question for myself. First off, let me link to the external resource which was the most helpful for this ...
Paul Stelian's user avatar
1 vote
Accepted

What is default IPv6 configuration on routers

It depends. You generally have a few modes: SLAAC. Clients pick their own IP, based on a announced subnet, which must be a /64. They get subnet and route from the RA announcements. DHCP6. Clients get ...
vidarlo's user avatar
  • 9,729
1 vote
Accepted

Is there a DHCPv6 equivalent of DHCPv4's private-use options?

After investigating this further myself... It would be better to use vendor-specific options rather than private-use options. (Eg I'm interested in making a network device which can query the DHCP ...
Craig McQueen's user avatar
1 vote
Accepted

Linux DHCPv6 server for PD on ppp interfaces

dhcpy6d works, but you need at least 0.7.2.99-5 version (at the moment of writing all the needed features are in beta) https://dhcpy6d.ifw-dresden.de/download/
Karol Jędrzejczyk's user avatar
1 vote

Windows Server 2016 IPv6 Hell

Depending on the size of the Enterprise, kill DNS scavenging, if it is a smaller environment. If it is larger, than that solution could be a bit messy and you may want to run a script occasionally ...
Techknow's user avatar
  • 166
1 vote

Unnamed devices in server 2012 dhcpv6

You can try looking up there mac address at this site. http://aruljohn.com/mac.pl It will tell you the manufacturer of the device. This may or may not be helpful but I have used it before to identify ...
George's user avatar
  • 11
1 vote
Accepted

How to set up IPv6 with Prefix Delegation (PD) on a Cisco ASA?

It turns out that the ASA firmware received support for DHCP6-PD (Prefix Delegation) in firmware 9.6. Unfortunately our ASA 5505 doesn't get anything newer than 9.2 so we'll need to upgrade to an ASA ...
Martijn Heemels's user avatar

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