Multiple instances of pihole-FTL running

Coro · July 2, 2020, 7:44am

Does this now work? It certainly works for me in a very quick test:

Concerning the latter, that might be a false-positive, they opened a PR to fix this yesterday:

github.com/pi-hole/pi-hole

Fix pihole status to not rely on a TCP port test

development ← fix/status_checking

opened 04:45PM - 01 Jul 20 UTC

DL6ER

+37 -6

**By submitting this pull request, I confirm the following:** - [X] I have r…ead and understood the [contributors guide](https://github.com/pi-hole/pi-hole/blob/master/CONTRIBUTING.md), as well as this entire template. - [X] I have made only one major change in my proposed changes. - [X] I have commented my proposed changes within the code. - [X] I have tested my proposed changes, and have included unit tests where possible. - [X] I am willing to help maintain this change if there are issues with it later. - [X] I give this submission freely and claim no ownership. - [X] It is compatible with the [EUPL 1.2 license](https://opensource.org/licenses/EUPL-1.1) - [X] I have squashed any insignificant commits. ([`git rebase`](http://gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html)) --- **What does this PR aim to accomplish?:** The current test can fail even when there is no error i case the max. number of TCP workers is reached. **How does this PR accomplish the above?:** Actually test if there is a `pihole*` process running on port 53. If so, analyze if we bound to IPv4/6 and UDP/TCP. If all four sockets are accepting/listening, we report that the DNS service is running. If some are missing, we report this, too. If no `pihole*` process is listening on port 53, then this is the new (better) criterion for saying: it is not running Example for when everything is fine: ``` $ pihole status [✓] DNS service is listening [✓] Pi-hole blocking is enabled ``` When, e.g., IPv6 is not available: ``` $ pihole status [✗] DNS service is partially listening [✓] UDP (IPv4) [✓] TCP (IPv4) [✗] UDP (IPv6) [✗] TCP (IPv6) [✓] Pi-hole blocking is enabled ``` Or, when FTL is offline: ``` $ pihole status [✗] DNS service is NOT listening ``` **What documentation changes (if any) are needed to support this PR?:** None

Ah, this reminds me of a discussion I've seen on Github yesterday, let's go into this more:

Yes, this:

This very much sounds like this (link to a specific comment in there, also from yesterday):

https://github.com/pi-hole/FTL/issues/816#issuecomment-652525050

TL;DR: Pi-hole imposes an upper limit of 20 concurrently running TCP workers at the same time as measure against a resource-exhaustion attack (after all, many Pi-hole are reachable from the public Internet, even when this is really not a good idea).

I checked git blame and this limit has always (at least since 2004) been there and is unchanged. Given the substantial improvement in memory and computing power since 2004, rising this limit is likely necessary!

@webdevelopers Maybe you want to increase the limit of concurrently allowed TCP connections from 20 to something substantially larger?
When more and more (I can only assume IoT) devices use "steady" TCP connections for their DNS, this seems a necessity. dnsmasq (and hence Pi-hole) rejects new TCP connections when the maximum number is reached. This doesn't seem to be the proper way of things (even when I understand why this is technically).