Inconsistent Issues With Wired Connection [SOLVED]

dancan12345 · 2017-07-04 14:53:40

Over the past day, I have experienced an issue whereby I'm unable to connect to webpages following (I believe) an update. It appears to be inconsistent though, affecting Firefox, pacman, ping and w3m but not google-chrome (from the AUR) and only on my current Arch install, not affecting my Xubuntu dual-boot. I am still able to ping IP addresses though domain names aren't resolved.

This led me to think that there must be some problem with the DNS, but drill returns the right IP addresses without any errors and, as I said, Chrome works fine and the rest of the network functions fine too so I don't know what to try next as the webpages don't report back any error numbers for me to go on.

UPDATE: I've also now reset my firewall but there is still no change in symptoms

lspci -k reports:

01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 0c)
	Subsystem: Gigabyte Technology Co., Ltd Onboard Ethernet
	Kernel driver in use: r8169
	Kernel modules: r8169

Any help or suggestions would be greatly appreciated.

Last edited by dancan12345 (2017-07-06 19:26:06)

seth · 2017-07-06 12:13:29

there must be some problem with the DNS

How do you configure your network?

systemctl list-units | grep -iE '(net|wicd|dhcp|conn)'

dancan12345 · 2017-07-06 14:41:36

I don't believe there to be an issue with my DNS as

drill google.com

returns

;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 42489
;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 
;; QUESTION SECTION:
;; google.com.	IN	A

;; ANSWER SECTION:
google.com.	299	IN	A	216.58.198.110

;; AUTHORITY SECTION:

;; ADDITIONAL SECTION:

;; Query time: 38 msec
;; SERVER: 8.8.4.4
;; WHEN: Thu Jul  6 15:38:42 2017
;; MSG SIZE  rcvd: 44

Your command returns:

sys-devices-pci0000:00-0000:00:1c.0-0000:01:00.0-net-enp1s0.device                        loaded active plugged   RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (Onboard Ethernet)
sys-subsystem-net-devices-enp1s0.device                                                   loaded active plugged   RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (Onboard Ethernet)
sys-fs-fuse-connections.mount                                                             loaded active mounted   FUSE Control File System                                                    
dhcpcd.service                                                                            loaded active running   dhcpcd on all interfaces                                                    
systemd-timesyncd.service                                                                 loaded active running   Network Time Synchronization                                                
network-pre.target                                                                        loaded active active    Network (Pre)                                                               
network.target                                                                            loaded active active    Network

seth · 2017-07-06 15:15:36

There're different resolving functions and sytemd-resolved doesn't operate on /etc/resolve.conf (leading to this particular split behavior) but you're just using dhcpcd, so the should really not be a problem.

ping uses libresolv, drill uses libldns. You'll find that

strace ping www.google.com 2>&1 | grep etc

doesn't touch /etc/resolv.conf while

strace drill www.google.com 2>&1 | grep etc

does.
What does /etc/nsswitch.conf look like, does it altered?

pacman -Qkk filesystem

dancan12345 · 2017-07-06 15:44:34

I don't have strace installed but pacman -Qkk filesystem reports:

backup file: filesystem: /etc/nsswitch.conf (Modification time mismatch)
backup file: filesystem: /etc/nsswitch.conf (Size mismatch)

Which is also reported for a number of other files as well (fstab, group, gshadow, hosts, passwd, resolv.conf, shadow and shells)

seth · 2017-07-06 15:49:44

What does /etc/nsswitch.conf look like?

There's likely a pacnew file you might want to diff.

(You don't need to strace the processes if you trust that I'm not making a fool out of myself ;-)

dancan12345 · 2017-07-06 15:58:59

I've checked - following the wiki instructions - and there aren't any pacnew files for /etc/nsswitch.conf. There is one for php.ini and the mirrorlist, but they weren't from recently.

seth · 2017-07-06 16:20:47

You can either (and preferably) compare it to the file in the package or upload it for inspection.

dancan12345 · 2017-07-06 16:44:12

tar -xOf /var/cache/pacman/pkg/filesystem-2017.03-2-x86_64.pkg.tar.xz etc/nsswitch.conf | diff /etc/nsswitch.conf -

Returns:

9,11c9
< hosts: files mymachines resolve [!UNAVAIL=return] mdns_minimal 
< [NOTFOUND=return] dns 
< myhostname
---
> hosts: files mymachines resolve [!UNAVAIL=return] dns myhostname

I presume I've done this right?

seth · 2017-07-06 18:50:03

Yes, and it's terribly suspicious.
Did you configure the "mdns_minimal [NOTFOUND=return]" in there or did this "happen" - do you have use for avahi hostname resolution?

In any case, try to replace the file with the stock version and test the resulting behavior (in doubt do a reboot)
In case that's it, the bug/problem is somewhere in avahi.

dancan12345 · 2017-07-06 19:22:13

No, I've never done anything with the file and I haven't got the Avahi daemon enabled.

Replacing the file worked and all applications using a network connection are working again; I ran the following command:

tar -xOf /var/cache/pacman/pkg/filesystem-2017.03-2-x86_64.pkg.tar.xz etc/nsswitch.conf > /etc/nsswitch.conf

Is there anything I should keep an eye out for or anything else I should do to make sure the issue doesn't come back?

dancan12345 · 2017-07-06 19:24:02

No, I've never done anything with the file and I haven't got the Avahi daemon enabled.

Replacing the file worked and all applications using a network connection are working again; I ran the following command:

tar -xOf /var/cache/pacman/pkg/filesystem-2017.03-2-x86_64.pkg.tar.xz etc/nsswitch.conf > /etc/nsswitch.conf

Is there anything I should keep an eye out for or anything else I should do to make sure the issue doesn't come back?

seth · 2017-07-06 19:29:20

Well, it's not much of a surprise that resolution failed if avahi wasn't even running.
You could check "pacman -Qi avahi" for the things that depend on it and maybe you recall related interaction with any of them, but I've really no idea what could injecting the mdns responder "implicitly" (because arch does not "implicitly") - maybe some AUR package?

dancan12345 · 2017-07-06 19:38:00

I recently build a printer driver (epson-inkjet-printer-201202w) in order to connect wirelessly to a printer and I got Google Chrome, GPodder and Spotify off it a while back, but apart from that, my builds off the AUR don't use the internet.

VLC and Mono are the only applications using Avahi as a dependancy so I don't know what might have caused it.

Arch Linux

#1 2017-07-04 14:53:40

Inconsistent Issues With Wired Connection [SOLVED]

#2 2017-07-06 12:13:29

Re: Inconsistent Issues With Wired Connection [SOLVED]

#3 2017-07-06 14:41:36

Re: Inconsistent Issues With Wired Connection [SOLVED]

#4 2017-07-06 15:15:36

Re: Inconsistent Issues With Wired Connection [SOLVED]

#5 2017-07-06 15:44:34

Re: Inconsistent Issues With Wired Connection [SOLVED]

#6 2017-07-06 15:49:44

Re: Inconsistent Issues With Wired Connection [SOLVED]

#7 2017-07-06 15:58:59

Re: Inconsistent Issues With Wired Connection [SOLVED]

#8 2017-07-06 16:20:47

Re: Inconsistent Issues With Wired Connection [SOLVED]

#9 2017-07-06 16:44:12

Re: Inconsistent Issues With Wired Connection [SOLVED]

#10 2017-07-06 18:50:03

Re: Inconsistent Issues With Wired Connection [SOLVED]

#11 2017-07-06 19:22:13

Re: Inconsistent Issues With Wired Connection [SOLVED]

#12 2017-07-06 19:24:02

Re: Inconsistent Issues With Wired Connection [SOLVED]

#13 2017-07-06 19:29:20

Re: Inconsistent Issues With Wired Connection [SOLVED]

#14 2017-07-06 19:38:00

Re: Inconsistent Issues With Wired Connection [SOLVED]

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