ULA prefix lifetime

[Paul D]

I proposed a 'fix' or, at least, a new feature to specify prefix lifetimes about a half-year ago which @Ansuel just reviewed a few days ago. 

See

[RFC PATCH 08/14] router: clamp prefix valid_lt to interface valid_lifetime

which... ideally should go in a separate patch (but this version depended on changes in the named patch-set)

It's in his inbox for further review/merge.

Otherwise prefixes stick around forever and start fucking shit up in your environment. I triggered a DoS in some systems which I won't name because of this >:)




On 2024-11-20 16:54, chriss wrote:
> Hi
> 
> I have the following scenario:
> 
> - a router with openwrt
> 
> - a (german) VDSL connection with IPv4 and IPv6
> 
> - a delegated IPv6 prefix (/56) that I use in my internal LAN segments
> 
> My problem:
> 
> I happens that I have to reconnect my VDSL (update of router, tripped over cable, whatever) - with that I get a new IPv6 prefix delegated. Now my clients have 2 prefixes/addresses. The old one (before the router reboot/reconnect) and a new one. That's bad because the old one won't route anymore. simple solution: set the lifetime to sth like 5min or so and the old addresses gets deprecated fast enough.
> 
> Now my ULA addresses have also a lifetime of 5min - which is bad because after 5 min of router downtime (update) I lose my local delivery between clients.
> 
> My solution (to this very specific and edge case problem) would be to set a large lifetime for ULA prefixes and use a short one for WAN delegated.
> 
> My idea would be to allow the user to set (optional) a ULA lifetime where one can specify the ULA prefix. The odhcpd process would then use this config entry and send RA with the respective lifetime.
> 
> 
> I write to gather feedback and maybe alternative solutions and if a path / PR for my solution would be accepted.
> 
> 
> 
> kind regards
> 
> //chriss
> 
> 
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