Comment by throw0101a | Hacker News Reader

Comment by throw0101a | Hacker News Reader

Parent Full thread

Actually it seems that it is not renegotiating everyday: it is expiring and re-requesting.

The way DHCP 'should' work is that when a client is part-way through the lease it should try to renew the IP it already has:

* https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Pro...

* https://tools.ietf.org/html/rfc2131#section-4.4.5

This allows the client to (hopefully) keep extending the IP it has so that a re-IP does not cause current connections to drop. If the modem is not doing this (can the OP log into it in someway to see logs?), then it is acting as a 'non-ideal' DHCP client.

Until this is sorted out, try rebooting the modem an an 'odd' hour that will not disrupt you during the day. This is no guarantee though: the DHCP server may remember the old/current DHCP lease and simply re-issue it with the same expiration time.

I'm on DSL/PPPoE, so this may not apply, but: my Asus router has a setting that allows it to automatically reboot. I do this at ~04h00 to get a new IP every day so help with privacy concerns. I generally surf with cookies disabled, so these two things help with the low-hanging fruit of simple tracking techniques. (My DSL modem is bridged.)

I had this exact issue in 2008 in SF on Comcast Business.

The lease would be dropped and renegotiated every few hours, we could notice it because our SSH tunnels would get torn down.

What was annoying was that the business plan had a static IP associated with it, presumably managed by their DHCP setup.

It took weeks to convince Comcast the issue wasn’t in our building, and moments for them to fix once they “got it”.

I saw this daily drop on several small biz Comcast setups. I recall I found it while looking through all the settings on the router, though I do recall having to call Comcast and they set something so it never happened again. It was the Comcast device with built in wifi. Hardwired didn't glitch, just wifi.

What piece of evidence or logs finally convinced Comcast that the issue was on their side?

Honestly my memory is not that good! I remember a few tech visits as they replaced modems, etc, and I eventually got to some “3rd level support person” that said something akin to “oh, that issue again”.

Did you try saying shibboleet?

https://xkcd.com/806/

c.f. Judges 12:5-6 (https://www.bible.com/bible/114/JDG.12.5-6.NKJV):

> The Gileadites seized the fords of the Jordan before the Ephraimites arrived. And when any Ephraimite who escaped said, “Let me cross over,” the men of Gilead would say to him, “Are you an Ephraimite?” If he said, “No,” then they would say to him, “Then say, ‘Shibboleth’!” And he would say, “Sibboleth,” for he could not pronounce it right. Then they would take him and kill him at the fords of the Jordan. There fell at that time forty-two thousand Ephraimites.

Haha - This is and the comment above are awesome. But not really a backdoor.

I could be wrong but this sounds more like NAT port issue given the frequency and static lease agreement on IP.

Reply on news.ycombinator.com