Re: IPv6 networking problems in 14.3

dhcpcd already has this behaviour.


Good luck!


Roy

 
 

 
 ---- On Mon, 15 Sep 2025 18:59:15 +0100  Karl Denninger<karl@denninger.net> wrote ----


 
 
   
   
    On 9/15/2025 13:20, Chris Ross wrote:
 
    
 
    
 
       
         
          On Sep 15, 2025, at 08:59, Karl Denninger 
            mailto:karl@denninger.net  wrote:
 
          
 
           
            
 
             
              Hmmmmm.... just came in via git pull:
 
                  dhclient: improve UDP checksum handling
 
                
 
                This could potentially apply to other bpf-using things 
                -- which includes dhcpcd.  And you have tso/lro turned 
                on.
 
              It is a patch to dhclient, not dhcpcd but does the same 
                issue potentially apply?
 
            
 
          
 
        
 
        
 
        
 
        I don’t know, but I think that isn’t my problem.  It seems like 
        the NS that
 
      dhcpcd is sending is alright, and tcpdump doesn’t see an NA 
        coming
 
      back in at all.
 
      
 
      
 
      - Chris
 
      
 
      
 
    
 
    Unfortunately without being able to snoop on the ONT's glass side 
      that's hard to diagnose; are they sending it at all, are they 
      sending it to the wrong place, does the ONT have a map that's 
      wrong between its fiber interface and the MAC connected to it, 
      etc.
 
    Fortunately the ISP I'm connected to when this sort of thing 
      happened to me had people who actually knew what they were doing 
      and were able to snoop the packets coming and going on their side 
      when I was on the phone with them.  Good luck getting a large ISP 
      like Verizon to connect you to someone with the appropriate level 
      of access into their gear to be able to do that.  It took me a 
      couple of rounds with KUB here before they went beyond "we cleared 
      our ARP table entry for your ONT but we don't know why it did 
      that" to getting someone on the line that actually was willing and 
      able to snoop the traffic and determine WHY it happened.
 
    The interesting part in this case (but probably the fortunate 
      part!) was that their infrastructure for delegating an IPv4 
      (single address, you do the NAT) and /56 IPv6 is apparently 
      entirely distinct thus that one had a hissy fit didn't prevent the 
      other from coming up and functioning.
 
    -- 
 
      Karl Denninger
 
      mailto:karl@denninger.net 
 
      The Market Ticker
 
      [S/MIME encrypted email preferred]