2021-08-03 Emacs Wiki and IPv6

Here’s something weird: I can no longer connect to Emacs Wiki. At first, I thought it was only a problem on my iPhone or iPad, but apparently it’s more widespread.

Could not connect to the server. NSURLErrorDomain

This is for Firefox and Safari which makes me think it’s a problem with the networking layer in the operating system, not the browser. I can connect just fine to the other domains hosted on the same machine (alike this one).

On my laptop, using traceroute:

alex@melanobombus ~> traceroute -n www.emacswiki.org
traceroute to www.emacswiki.org (178.209.50.237), 30 hops max, 60 byte packets
…
12  178.209.50.237  7.562 ms  7.605 ms  4.772 ms
alex@melanobombus ~> traceroute -n -4 emacswiki.org
traceroute to emacswiki.org (178.209.50.237), 30 hops max, 60 byte packets
…
12  178.209.50.237  2.809 ms  5.176 ms  5.716 ms
alex@melanobombus ~> traceroute -n -6 www.emacswiki.org
www.emacswiki.org: Name or service not known
Cannot handle "host" cmdline arg `www.emacswiki.org' on position 1 (argc 3)
alex@melanobombus ~> traceroute -n -6 emacswiki.org
traceroute to emacswiki.org (2a02:418:6a04:178:209:50:237:1), 30 hops max, 80 byte packets
…
12  2a02:418:6a04:178:209:50:237:1  8.651 ms  9.542 ms  7.917 ms

Apparently, there’s an IPv6 problem for www.emacswiki.org but not for emacswiki.org?

Checking DNS…

@ 10800 IN SOA ns1.gandi.net. hostmaster.gandi.net. 1589061328 10800 3600 604800 10800
@ 10800 IN A 178.209.50.237
@ 10800 IN AAAA 2a02:418:6a04:178:209:50:237:1
@ 10800 IN MX 10 aspmx1.migadu.com.
@ 10800 IN MX 20 aspmx2.migadu.com.
@ 10800 IN TXT "openpgp4fpr:df9446eb7b7846387ccc018bc78ca29bacecfeae"
@ 10800 IN TXT "v=spf1 a mx include:spf.migadu.com ~all"
_dmarc 10800 IN TXT "v=DMARC1; p=reject"
default._domainkey 10800 IN TXT "v=DKIM1; k=rsa; s=email; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCmaqj01Yu19QPNpkSbuQJNZ8OIe4h3gYw3WPqdDxC0OIN5HMxlNFE3AWcpgdmjgjBF2a3X63Ux8PExP6f0qPBoiMO0wvV3MhSwF1kXwuzuhTgtlwf+3v7EIGytQJ8+Y88+bgRfRhaRQfkTeEw1EI2/5yLeEWpqZOdV3tYyvx8dawIDAQAB"
www 10800 IN A 178.209.50.237

That’s right: no AAAA record for www!

For the moment, dig is reporting it’s OK:

alex@melanobombus ~> dig -t AAAA www.emacswiki.org

; <<>> DiG 9.11.5-P4-5.1+deb10u5-PureOS <<>> -t AAAA www.emacswiki.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12984
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;www.emacswiki.org.		IN	AAAA

;; ANSWER SECTION:
www.emacswiki.org.	10800	IN	AAAA	2a02:418:6a04:178:209:50:237:1

;; Query time: 24 msec
;; SERVER: …
;; WHEN: Tue Aug 03 07:40:42 CEST 2021
;; MSG SIZE  rcvd: 74

alex@melanobombus ~> dig -6 -t AAAA www.emacswiki.org

; <<>> DiG 9.11.5-P4-5.1+deb10u5-PureOS <<>> -6 -t AAAA www.emacswiki.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7984
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;www.emacswiki.org.		IN	AAAA

;; ANSWER SECTION:
www.emacswiki.org.	10631	IN	AAAA	2a02:418:6a04:178:209:50:237:1

;; Query time: 4 msec
;; SERVER: …
;; WHEN: Tue Aug 03 07:43:31 CEST 2021
;; MSG SIZE  rcvd: 74

Well, that alone does not fix it. How strange.

alex@melanobombus ~> traceroute -n -6 www.emacswiki.org
www.emacswiki.org: Name or service not known
Cannot handle "host" cmdline arg `www.emacswiki.org' on position 1 (argc 3)

Firefox also seems to be caching the info somewhere. I always suspect that it has its own DNS subsystem somewhere. In any case, setting “network.dnsCacheExpiration” and “network.dnsCacheExpirationGracePeriod” both to 0 and then back to 60 did not help.

But yeah, something is still amiss. It’s not just Firefox – curl is doing it, too:

alex@melanobombus ~> curl -I https://emacswiki.org
HTTP/1.1 301 Moved Permanently
Date: Tue, 03 Aug 2021 05:36:31 GMT
Server: Apache
Permissions-Policy: interest-cohort=()
Location: https://www.emacswiki.org/
Content-Type: text/html; charset=iso-8859-1

alex@melanobombus ~> curl -I https://www.emacswiki.org
curl: (7) Failed to connect to www.emacswiki.org port 443: Connection refused

Comments

Looks like we’re back! I wonder why this happened. Did somebody switch on IPv6 and no other Emacs Wiki user ever used IPv6?

– Alex 2021-08-03 06:55 UTC


Firefox might be using DoH (DNS over HTTP) with a default server at CloudFlare. You can either force it back to using normal DNS, or (like I finally did) run your own DoH service because that’s the new hipster, secure thing to do or some $#!? like that.

Sean Conner 2021-08-04 02:11 UTC


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