SLAAC versus DHCPv6
-
I have debated SLAAC vs. DHCPv6 myself. At the end, I prefer SLAAC as it's "hands off" easy management.
The issue I have ran into is with RA. When I enable SLAAC (fully disable DHCPv6) and set the router priority to HIGH and advertise my Pihole instance for IPv4 + IPv6 DNS server, the Pihole instance gets inundated with new IPv6 clients to the point of where there will be thousands of clients registered in Pihole, bogging it down, even though there are only ~30 devices on my network. Is this due to the SLAAC privacy IP rotation?
I have never been able to solve this. I have no issues when I leave RA DNS servers as default (router).
-
@Jung-Fernmelder Honestly, IPv6 client side is just not industry mature yet. It works fine - if you can control everything on the clients, but there are WAY to many options/standards or OS/vendor specific issues to make IPv6 really easy to use AND manage.
It’s a pita that they cock’ed up IPv6 so much. There was a lot of potential in IPv6 before all the petty squables and lack of unified standards broke everything.
As long as an IPv4 address is required to reach all corners of the Internet, just disable IPv6, and make your life A LOT easier.
Love the no fuss of using the official appliances :-)
-
I think the real issue is that for consumers SLAAC was supposed to make provisioning of single segment home networks "just work". But then ISP's being the center of all control didn't follow the outlined best practice that a /54 or /60 is the base prefix and allowing the IPv6 addresses to be "persistent". Too many ISP's only will issue a /64 for one segment, expire the address every 24 hours forcing the network and devices to re-address each time.
If things were different, I would have engineered IPv6 internet where I pay per year for a block of IPv6 addresses /54 and that would be portable to any ISP and the ISP just becomes a pipe. The ISP shouldn't have the power to revoke address's based on a policy that blows in the wind.
One the client side there would be only two rules SLAAC or DHCPv6 assisted by SLAAC for router and DNS information for static addressing.
-
@keyser said in SLAAC versus DHCPv6:
It’s a pita that they cock’ed up IPv6 so much.
No. It was Google that didn't enable DHCPv6 on Android or Chrome devices.
-
@JKnott said in SLAAC versus DHCPv6:
No. It was Google that didn't enable DHCPv6 on Android or Chrome devices.
It’s a little more complicated than that - I have yet to successfully directly attach pfSense to an ISP and have IPv6 working (tried 4 different ISPs that all “supports” IPv6 now). If you set it up behind the ISPs router where they have made sure basic Windows/Linux clients work, then pfSense will also work. But anything directly linked to the ISP fiber/bridgemode box is a PITA to get IPv6 working properly.
The problems comes from the MILLIONS of options both the SLAAC and the DHCP 6 proces offers, and if the client does not send the right parameters, use the correct intervals or accepts persistence, something/everything IPv6 related stops working.
On top of that the DHCP6c Client in pfSense doesn’t support many of the DHCPv6 options that I have seen ISP’s require to get IPv6 going - Or it doesn’t support the specific combo of settings/intervals needed to keep it going after the intial lease is accepted.Granted - this is mainly the ISPs that are cock’ing up things, but the fact that it CAN require so much special config with very specific settings and configurations to get basic DHCPv6 going just shows it’s not matured yet (or standardized properly)
-
@ronv42 said in SLAAC versus DHCPv6:
Too many ISP's only will issue a /64 for one segment, expire the address every 24 hours forcing the network and devices to re-address each time.
If things were different, I would have engineered IPv6 internet where I pay per year for a block of IPv6 addresses /54
You are describing the difference between a static and dynamic IP address.
-
Static is better for a public or at least internet accessible server (dynamic Domain name not required)
-
Dynamic is better for user privacy (IP with mask shows ISP user has used to access internet rather than which user internet account was used).
-
-
@Patch said in SLAAC versus DHCPv6:
You are describing the difference between a static and dynamic IP address.
If the ISP honours the DUID the prefix should be essentially static. I've had the same prefix for well over 5 years. That's "static" enough for me.
-
@JKnott
Not sure why that was addressed to me. I was describing the different use case for static and dynamic IP, not how to get a static IP. -
Well, I did respond to your post. However, the last line about dynamic is better for privacy is wrong. With SLAAC you get up to 7 privacy addresses, based on a random number. You get a new one every day, with the oldest falling off the list. The most recent is the address used for outgoing connections. The consistent address, which can be based on either the MAC address or a random number, can be used for things like VPN access to your network. Unless the DHCPv6 address changes every day, it's actually worse for privacy.
-
@JKnott I don't know if you have Comcast or not. I am fighting them for a site I just hooked up in Northbrook, Illinois. Every 24 hours they re-allocate the darn IPv6. They are handing out a /60 but it's a PITA I will be removing their Xfinity gateway and going with a vanilla cable modem and seeing if this gets rid of the IP address swaps they are doing. Comcast plays so many games to upsell features you will never use though their crappy gateway to get a discount.
-
I'm on Rogers and they use the same equipment as Comcast. However, there is a setting in pfSense that may affect this. It's System / Advanced / Networking / Do not allow PD/Address release. If that's not selected, the prefix will change frequently.
-
@JKnott said in SLAAC versus DHCPv6:
line about dynamic is better for privacy is wrong. With SLAAC you get up to 7 privacy addresses, based on a random number.
they are all in the same range provided by the ISP, readily revealed by masking the address of any one of these addresses.
- A dynamic ISP address range publishes which ISP the user is connected to the internet by
- A static ISP address publishes your personal address range
Then if one of the devices on your network has location services enabled for "Network & Wireless" or through your browser then the "privacy" addresses have your street address encoded in every internet communication.
Recording addresses over time is likely to reveal what the 7 "private" addresses are for each device.
So a static IP address range is not really very private at all in my opinion.
-
@Patch said in SLAAC versus DHCPv6:
they are all in the same range provided by the ISP, readily revealed by masking the address of any one of these addresses.
A dynamic ISP address range publishes which ISP the user is connected to the internet by
A static ISP address publishes your personal address range
recording addresses over time is likely to reveal what the 7 "private" addresses are for each deviceMy WAN address is provided by DHCPv6, along with my prefix. It makes no difference whether I use SLAAC or DHCPv6 on my LAN, with regard to my prefix. It will be the same either way. The only issue is whether the ISP will honour the DUID.
One other thing, with the huge address block within a /64, an attacker would have a hard time finding something to attack, even if they knew the prefix. A single /64 contains 18.4 billion, billion addresses. Compare this to a bit over 4 billion for the entire IPv4 address range. Of course there's a firewall called pfSense that goes a long way to keeping attackers out!
-
@JKnott said in SLAAC versus DHCPv6:
One other thing, with the huge address block within a /64, an attacker would have a hard time finding something to attack, even if they knew the prefix. A single /64 contains 18.4 billion, billion addresses. Compare this to a bit over 4 billion for the entire IPv4 address range. Of course, there's a firewall called pfSense that goes a long way to keeping attackers out!
Now do the math with a /60: 16 x 18.4 billion - There is a reason I never see IPv6 address scans, but I still see port scans once a nefarious site logs your IPv6 they have the basic IP subnet, and it would take forever to scan through all those addresses.
-
With my /56, it's 256 /64s. Yeah, it would take a while. I mentioned privacy addresses. They have a lifetime of 7 days. After that, they'd have to start over to find another address.
-
Here is the guy who started the conversation. Thank you very much for all the information and the discussion. This helps me.
Conclusion:
Use SLAAC for clients and DHCPv6 for servers.@keyser said in SLAAC versus DHCPv6:
is a PITA to get IPv6 working properly
+1
IPv6 is much more complicated than IPv4. And that's okay. Everybody involved in networking should be able to learn the IPv6 basics.
But the ISPs have messed it up, espceially with frequent prefix renewals which are heavy to handle and unnecessary. Three or four IPv6 prefix renewals per year would be enough. -
@JKnott said in SLAAC versus DHCPv6:
It makes no difference whether I use SLAAC or DHCPv6 on my LAN, with regard to my prefix
Correct
@JKnott said in SLAAC versus DHCPv6:
One other thing, with the huge address block within a /64, an attacker would have a hard time finding something to attack
That is not an address privacy issue, but it maybe part of a network servers exposure to the internet. Network protection by obfuscation is not really a good approach, as it fails repidly if someone takes the time to look especially if they can get a hint were to look from another source (human engineering, traffic monitoring etc). Direct protection using a decent firewall is far better.
@JKnott said in SLAAC versus DHCPv6:
With SLAAC you get up to 7 privacy addresses, based on a random number.
As I have tried to explain, 7 networks addresses is a tiny number and everyone of these addresses has the same prefix.
-
If your ISP is giving you a static prefix, the the prefix will almost certainly encode / reveal your street address every time you make an internet connection from any device on your local network. My interpretation of which is the "SLAAC Privacy addresses" you are using maybe making you feel you have achieved something but they actually provide almost no privacy functionality.
-
If your ISP is giving you a dynamic prefix, the prefix will encode / reveal what ISP you are using but not which service or your street address. If you then add some randomisation of the lower order bits for each device you may achieved some privacy (not as much as a VPN or routing randomisation Tor tries to achieve).
@Jung-Fernmelder said in SLAAC versus DHCPv6:
ISPs have messed it up, espceially with frequent prefix renewals which are heavy to handle and unnecessary.
They are offering some internet privacy to those user who like some privacy. If you don't value privacy then perusing the options for a static IP address would be appropriate for you.
-
-
@keyser said in SLAAC versus DHCPv6:
is a PITA to get IPv6 working properly
Well could you, or someone else, explain for non native english speakers what "PITA" in this context means. If i g00gle it i just learn what i already know, PITA is nice greek food. But for sure you don't talk about nice greek food but more about something like a pain ;-)
-
@eagle61 said in SLAAC versus DHCPv6:
@keyser said in SLAAC versus DHCPv6:
is a PITA to get IPv6 working properly
Well could you, or someone else, explain for non native english speakers what "PITA" in this context means. If i g00gle it i just learn what i already know, PITA is nice greek food. But for sure you don't talk about nice greek food but more about something like a pain ;-)
PITA = Pain In The As* -
@keyser said in SLAAC versus DHCPv6:
PITA = Pain In The As*
Thanks very much. And yes food also may some times result in PITA, but more likely not greek food, but maybe very spicy food from India or other south east Asia countries ;-)
I know its off topic - sorry for that.
