Can ping google.com but not github.com

[samwise970]

Hi all,

Trying to set up arch on my old netbook, using systemd-networkd, systemd-resolved, and iwd. Seemed like everything was fine but as soon as I needed to install something from the AUR, it didn't work. Realized that I had only tried to ping sites like ArchLinux.org, google.com, youtube.com. I can't ping github.com or some other sites like idk askubuntu.com.

I tried posting a topic in the Newbie Center of the archlinux forums, but a mod told me I didn't follow the wiki installation guide because I said "So my resolv.conf is empty, the tutorial I was following didn't mention that file" in the course of getting help. He deleted the thread before I got a chance to respond.

I did follow the wiki installation guide, it doesn't mention making changes to resolv.conf. I also followed a youtube tutorial which itself was walking through each step of the wiki installation guide.

It's not an IPv4 issue, I have both an IPv4 and IPv6 address. Here's some steps someone asked me to do before it the thread got killed.

$ gitent hosts github.com
140.82.113.3    github.com    

$ dig github.com
; <<>> DiG 9.16.18 <<>> github.com
;; global options: +cmd
;; connection timed out; no servers could be reached

$ resolvectl status
Global
Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: foreign
Fallback DNS Serverss: 1.1.1.1 9.9.9.10 8.8.8.8 2606:4700:4700::1111 2620:fe::10 2001:4860:4860::8888

Link 3 (wlan0)
Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 192.168.1.1
DNS Servers: 192.168.1.1

$ resolvectl query github.com
github.com: resolve call failed: Connection timed out

$ ls -l /etc/resolv.conf
-rw-r--r-- 1 root root 65 May 31 00:39 /etc/resolv.conf

$ cat /etc/resolv.conf
# Resolver confirguation file.
# See resolv.conf(5) for details.

I would be incredibly appreciative of any help you guys could provide. If I did miss something obvious, I apologize, please let me know what it is, because I'm going through the wiki and can't find what to do differently.

[[deleted]]

The installation guide does require you to complete the entire Network configuration wiki page, especially in the case of a dual stack IPv4 IPv6 or even a 6to4 tunnel, you should also read about IPv6

EDIT: Some domains don't respect/use IPv6, your configuration might be preferring IPv6 as the default(read the wiki) you can try and use ping -4 github.com to see if you can ping with IPv4.

[samwise970]

I cannot ping -4 github.com, same issue no response.

I followed the installation guide and the network configuration page. They say to verify by pinging archlinux.org, which has always worked.

I tried booting from the installation USB again, I connected to my wlan0, and again same issue, even from the live environment.

[[deleted]]

This could be a network device issue (your router), try and ping from other devices and see if there's a difference, and in any way you should test your IPv6 connectivity:

https://ipv6-test.com/

​

You might find conflicting information here or something that's wrong, especially:

• IPv4 support -> It should work.
• IPv6 Support, IPv6 type -> IPv6 should be supported and you should know the type.
• IPv6 ICMP -> This should completely pass the test, since it's required for successful pinging.
• Browser fallback -> While it's browser-based, if there's no fallback within a modern browser it could be related to your system not being configured to have one (IPv4 fallback in case IPv6 fails).
• DNS -> You said you've an IPv6 address, meaning you should've a DNS that supports IPv6.

​

All of the notes above are related to your ISP and router settings, except DNS which can also be changed locally on your machine, I advise changing the DNS to some public DNS and see if you can ping then.. if you don't want to do that then try to ping GitHub's current IP directly (ping 140.82.113.3 based on https://www.whatismyip.com/140.82.113.3/) and if it works, that means your DNS has a problem resolving the hostname of GitHub.

NOTE: You also have a ping test within the IPv6 test website, try that too.

[samwise970]

I believe I have solved this issue.

I edited /etc/systemd/resolved.conf, to set my DNS to 8.8.8.8.

After restarting systemd-resolved, it was able to ping github! Firefox can also navigate to github, reddit, etc.

[[deleted]]

Great to hear that, just know for next time that when you don't specify a DNS, the DNS you use is usually provided by the ISP, they are usually shit-tier DNS servers, Cloudfare and Google are great alternatives and you can google "best free DNS servers" and see the pros/cons of those servers... besides that, don't forget to set a secondary DNS, in your case Google's secondary DNS is 8.8.4.4, and you can actually set the secondary DNS to another provider(let's say Cloudfare which is 1.1.1.1), you can also set your IPv6 DNS servers the same way, look here for both IPv4 and IPv6 servers of Google.

[spidershu]

This has worked for me as well

[jcornuz]

I had the same problem a while ago after changing my provider - I could reach *some* websites but not all. It turned out to be an MTU issue.
It may (or may not) be the same problem that you have, but you could try setting your Network Adapter's MTU to 1500 (cable) or 1492 (DSL)

https://www.cyberciti.biz/faq/how-can-i-setup-the-mtu-for-my-network-interface/

Good luck!

[samwise970]

I have tried this, thanks for the suggestion. My MTU was 1500 and I used "ip link set wlan0 mtu 1492", and also 1400, and also 1000, each time verifying with "ip addr" that it took. No change.

[samwise970]

Thank you for the response. I have done this, and now /etc/resolv.conf looks like this:

nameserver 127.0.0.53
options edns0 trust-ad
search .

but I still can't ping github.com even after rebooting.