Re: [solved] Re: Network suddenly stopped working
On Mon, Jul 12, 2021 at 02:32:12PM +0200, Michael Lange wrote: > Hi, > > On Mon, 12 Jul 2021 13:16:13 +0200 > wrote: > > (...) > > Your network clearly *thinks* it is up [...] > well, as you may have guessed I am completely stupid when it comes to > networking :) Most of us are. I know I am. > The symptom, as far as I can tell, is that just any attempt to connect to > the internet failed. Trying to ping my desktop machine from the laptop > just gave me "Destination Host Unreachable" messages. With ifconfig I > could see that no IPv4 address seemed to be assigned. And trying ifdown > followed by ifup was not possible, because ifdown seemingly refused to > work. When you posted ifconfig's output here, your interface seemed to be up, so /something/ must have changed on the way... [...] > So either one of these commands did some magic or something running in > the background fixed whatever issue there was. Proceed with fingers crossed :-) Cheers - t signature.asc Description: Digital signature
[solved] Re: Network suddenly stopped working
Hi, On Mon, 12 Jul 2021 13:16:13 +0200 wrote: (...) > Your network clearly *thinks* it is up. What makes you think your net > doesn't work? (not that I'm doubting your perception, but a more precise > symptom description might shed some light on the problem). well, as you may have guessed I am completely stupid when it comes to networking :) The symptom, as far as I can tell, is that just any attempt to connect to the internet failed. Trying to ping my desktop machine from the laptop just gave me "Destination Host Unreachable" messages. With ifconfig I could see that no IPv4 address seemed to be assigned. And trying ifdown followed by ifup was not possible, because ifdown seemingly refused to work. > > What does (either) "/sbin/route -n" or "ip route show" say? Oddly, now, without me consciously doing something, except running the commands Reco and you suggested, the network seems to work again. So either one of these commands did some magic or something running in the background fixed whatever issue there was. The network still works after a reboot (I had tried rebooting several times before, without effect), so I guess I'll never now what caused these troubles and how they were fixed. (the output of your commands looks normal now I think, so there is no point in posting it here). Thanks, and best regards Michael
Re: Network suddenly stopped working
On Mon, Jul 12, 2021 at 01:00:08PM +0200, Michael Lange wrote: > Does that tell something? Yep. First, your interface name is "enp2s0" has not changed. Second, someone (another instance of dhclient probably) have obtained a lease, as indicated by both tcpdump and "ip a" outputs. Reco
Re: Network suddenly stopped working
On Mon, Jul 12, 2021 at 01:00:08PM +0200, Michael Lange wrote: [...] > 2: enp2s0: mtu 1500 qdisc pfifo_fast state > UP group default qlen 1000 > link/ether 50:e5:49:d8:51:94 brd ff:ff:ff:ff:ff:ff > inet 192.168.178.27/24 brd 192.168.178.255 scope global dynamic enp2s0 >valid_lft 863861sec preferred_lft 863861sec > inet6 fe80::52e5:49ff:fed8:5194/64 scope link >valid_lft forever preferred_lft forever > > Does that tell something? Your network clearly *thinks* it is up. What makes you think your net doesn't work? (not that I'm doubting your perception, but a more precise symptom description might shed some light on the problem). What does (either) "/sbin/route -n" or "ip route show" say? Cheers - t signature.asc Description: Digital signature
Re: Network suddenly stopped working
Hi, On Mon, 12 Jul 2021 13:32:48 +0300 Reco wrote: (...) > does not add up. > > If, for some reason, an interface name had changed - you won't see > "enp2s0" in the ifconfig output. thanks for the clarification. > > > > some sources I found suggest to look at > > /etc/udev/rules.d/70-persistent-net.rules but there is nothing in that > > file that is not commented out, so I guess that this mechanism may be > > outdated. > > It is outdated, and that file should not be present at all. Ok, thanks. (...) > Troubleshooting steps: > > 1) Obtain tcpdump unless it's installed already. > 2) As root, run "tcpdump -pni any udp port 67 or udp port 68", and let > it run for a while. > 3) As root, run "dhclient enp2s0". > 4) Wait for a minute or so, terminate both tcpdump and dhclient. > 5) Post the output of steps 2 and 3, plain text preferred, add an output > of "ip a" for a good measure please. Ok, here is what I get: # tcpdump -pni any udp port 67 or udp port 68 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on any, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes 12:45:25.021291 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:45:40.099508 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:45:59.837396 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:45:59.839837 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:46:04.723115 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:46:04.725104 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:46:42.878014 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:47:00.290058 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:47:23.566465 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 12:47:55.826397 IP 192.168.178.1.67 > 192.168.178.27.68: BOOTP/DHCP, Reply, length 548 ^C 10 packets captured 10 packets received by filter 0 packets dropped by kernel # dhclient enp2s0 RTNETLINK answers: File exists (this command always returns immediately; when I enter it a new entry to the tcpdump output is added) # ip a 1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: enp2s0: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 50:e5:49:d8:51:94 brd ff:ff:ff:ff:ff:ff inet 192.168.178.27/24 brd 192.168.178.255 scope global dynamic enp2s0 valid_lft 863861sec preferred_lft 863861sec inet6 fe80::52e5:49ff:fed8:5194/64 scope link valid_lft forever preferred_lft forever Does that tell something? Regards Michael
Re: Network suddenly stopped working
Hi. On Mon, Jul 12, 2021 at 12:16:59PM +0200, Michael Lange wrote: This: > With ifconfig the enp2s0 interface appears to be up, combined with this: > I suspected udev to have for some reason changed the interface name; does not add up. If, for some reason, an interface name had changed - you won't see "enp2s0" in the ifconfig output. > some sources I found suggest to look at > /etc/udev/rules.d/70-persistent-net.rules but there is nothing in that > file that is not commented out, so I guess that this mechanism may be > outdated. It is outdated, and that file should not be present at all. > The output of `systemctl status networking.service` looks like this: In other words, it is useless. A usual thing, nothing unexpected. Troubleshooting steps: 1) Obtain tcpdump unless it's installed already. 2) As root, run "tcpdump -pni any udp port 67 or udp port 68", and let it run for a while. 3) As root, run "dhclient enp2s0". 4) Wait for a minute or so, terminate both tcpdump and dhclient. 5) Post the output of steps 2 and 3, plain text preferred, add an output of "ip a" for a good measure please. Reco
Network suddenly stopped working
Hi, since yesterday the network on my buster system all of a sudden refuses to work. I am using systemd, no network-manager is running. The /etc/network/interfaces file looks (as it did before) like: auto lo iface lo inet loopback allow-hotplug enp2s0 iface enp2s0 inet dhcp With ifconfig the enp2s0 interface appears to be up, the line that should look similar to inet 192.168.178.33 netmask 255.255.255.0 broadcast 192.168.178.255 misses, though. Trying `ifdown enp2s0` the command seems to never return. I suspected udev to have for some reason changed the interface name; some sources I found suggest to look at /etc/udev/rules.d/70-persistent-net.rules but there is nothing in that file that is not commented out, so I guess that this mechanism may be outdated. The output of `systemctl status networking.service` looks like this: ● networking.service - Raise network interfaces Loaded: loaded (/lib/systemd/system/networking.service; enabled; vendor preset: enabled) Active: active (exited) since Mon 2021-07-12 10:40:20 CEST; 1h 27min ago Docs: man:interfaces(5) Process: 7545 ExecStart=/sbin/ifup -a --read-environment (code=exited, status=0/SUCCESS) Main PID: 7545 (code=exited, status=0/SUCCESS) Jul 12 10:40:19 miniac systemd[1]: Starting Raise network interfaces... Jul 12 10:40:20 miniac systemd[1]: Started Raise network interfaces. I a not sure what to make of all this, does anyone have a clue what else I might try? Thanks in advance Michael
