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#1 2015-09-27 11:41:38

lyovushka
Member
Registered: 2015-09-27
Posts: 5

[Solved] Problems with wired connection

Hi all,

I am having problems connecting to wired network of my uni. The problems started yesterday and were not a result of an update. The other computer in the household which runs windows 7 connects just fine, so I presume the problem can be fixed on my side.

I normally use netctl and get a dynamic ip from the network. But now it fails and when I run 

sudo dhcpcd enp0s20u4u1

I get

enp0s20u4u1: adding address fe80::3060:ac8b:7239:45e5
enp0s20u4u1: waiting for carrier
enp0s20u4u1: carrier acquired
DUID 00:01:00:01:1c:7b:a7:72:00:23:56:6c:39:46
enp0s20u4u1: IAID 4c:b8:03:23
enp0s20u4u1: carrier lost
enp0s20u4u1: carrier acquired
enp0s20u4u1: adding address fe80::3060:ac8b:7239:45e5
enp0s20u4u1: IAID 4c:b8:03:23
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: soliciting an IPv6 router
enp0s20u4u1: offered 10.38.186.129 from 163.1.158.81
enp0s20u4u1: probing static address 10.38.186.129/23
enp0s20u4u1: ignoring offer of 192.168.1.101 from 192.168.1.254
enp0s20u4u1: NAK: wrong server-ID from 192.168.1.254
enp0s20u4u1: message: wrong server-ID
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 10.38.186.129 from 163.1.158.81
enp0s20u4u1: probing static address 10.38.186.129/23
enp0s20u4u1: ignoring offer of 192.168.1.101 from 192.168.1.254
enp0s20u4u1: NAK: wrong server-ID from 192.168.1.254
enp0s20u4u1: message: wrong server-ID
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.101 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.186.129 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81
enp0s20u4u1: message: requested address not available
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.101 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.186.129 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81
enp0s20u4u1: message: requested address not available

So I tried dhclient and when I run 

 sudo dhclient -v enp0s20u4u1

I get

Internet Systems Consortium DHCP Client 4.3.3
Copyright 2004-2015 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/enp0s20u4u1/00:e0:4c:b8:03:23
Sending on   LPF/enp0s20u4u1/00:e0:4c:b8:03:23
Sending on   Socket/fallback
DHCPREQUEST on enp0s20u4u1 to 255.255.255.255 port 67
DHCPNAK from 10.38.187.254
DHCPDISCOVER on enp0s20u4u1 to 255.255.255.255 port 67 interval 4
DHCPREQUEST on enp0s20u4u1 to 255.255.255.255 port 67
DHCPOFFER from 192.168.1.254
DHCPNAK from 10.38.187.254
DHCPACK from 192.168.1.254
bound to 192.168.1.101 -- renewal in 39056 seconds.

Now I get an address. But then I can ping 192.168.1.254 but when I ping 8.8.8.8 I get

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
From 192.168.1.254 icmp_seq=1 Destination Net Unreachable
From 192.168.1.254 icmp_seq=2 Destination Net Unreachable
From 192.168.1.254 icmp_seq=3 Destination Net Unreachable

So I can't access the Internet. Any help is much appreciated.

Last edited by lyovushka (2015-10-01 19:27:18)

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#2 2015-09-27 16:17:04

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 20,349

Re: [Solved] Problems with wired connection

Hello, and welcome to Arch Linux smile

lyovushka wrote:

I normally use netctl and get a dynamic ip from the network. But now it fails and when I run 

sudo dhcpcd enp0s20u4u1

I get....

You should not run dhcpcd or dhclient when using netctl.   Netctl will invoke dhcpcd (or dhclient) when it needs them.  If there is a service running that provides dhcp client services, they will wrestle for control of the network.

Please post the output of find /etc/systemd
and of systemctl status[ --no-pager

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#3 2015-09-27 16:37:35

lyovushka
Member
Registered: 2015-09-27
Posts: 5

Re: [Solved] Problems with wired connection

I get the same result when I invoke dhcpcd or dhclient through netctl. I run them manually to get their detailed output. Here is the result of commands you requested.

find /etc/systemd

/etc/systemd
/etc/systemd/network
/etc/systemd/system
/etc/systemd/system/multi-user.target.wants
/etc/systemd/system/multi-user.target.wants/remote-fs.target
/etc/systemd/system/getty.target.wants
/etc/systemd/system/getty.target.wants/getty@tty1.service
/etc/systemd/system/display-manager.service
/etc/systemd/user
/etc/systemd/system.conf
/etc/systemd/user.conf
/etc/systemd/journald.conf
/etc/systemd/coredump.conf
/etc/systemd/bootchart.conf
/etc/systemd/logind.conf
/etc/systemd/journal-remote.conf
/etc/systemd/journal-upload.conf
/etc/systemd/timesyncd.conf
/etc/systemd/resolved.conf
systemctl status --no-pager

● timbaka
    State: degraded
     Jobs: 0 queued
   Failed: 1 units
    Since: Sat 2015-09-26 18:25:33 BST; 23h ago
   CGroup: /
           ├─1 /sbin/init
           ├─system.slice
           │ ├─dbus.service
           │ │ └─306 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
           │ ├─system-netctl.slice
           │ │ └─netctl@wlp2s0\x2dsvolach.service
           │ │   ├─7817 wpa_supplicant -q -B -P /run/wpa_supplicant_wlp2s0.pid -i wlp2s0 -D nl80211,wext -c/run/net...
           │ │   └─7906 dhcpcd -4 -q -t 30 -L wlp2s0
           │ ├─systemd-journald.service
           │ │ └─167 /usr/lib/systemd/systemd-journald
           │ ├─udisks2.service
           │ │ └─435 /usr/lib/udisks2/udisksd --no-debug
           │ ├─upower.service
           │ │ └─455 /usr/lib/upower/upowerd
           │ ├─systemd-logind.service
           │ │ └─307 /usr/lib/systemd/systemd-logind
           │ ├─systemd-udevd.service
           │ │ └─191 /usr/lib/systemd/systemd-udevd
           │ ├─polkit.service
           │ │ └─383 /usr/lib/polkit-1/polkitd --no-debug
           │ └─sddm.service
           │   ├─312 /usr/bin/sddm
           │   └─322 /usr/lib/xorg-server/Xorg -nolisten tcp -auth /var/run/sddm/{46f7ea2c-05f6-4be0-883f-f802162b2...
           └─user.slice
             ├─user-1000.slice
             │ ├─user@1000.service
             │ │ ├─345 /usr/lib/systemd/systemd --user
             │ │ └─346 (sd-pam)
             │ └─session-c2.scope
             │   ├─ 344 /usr/lib/sddm/sddm-helper --socket /tmp/sddm-auth18c1ca9c-6e94-4394-982f-f24e1481b755 --id ...
             │   ├─ 349 lxqt-session
             │   ├─ 357 dbus-launch --sh-syntax --exit-with-session
             │   ├─ 358 /usr/bin/dbus-daemon --fork --print-pid 5 --print-address 15 --session
             │   ├─ 375 openbox
             │   ├─ 378 /usr/bin/xss-lock -- xscreensaver-command -lock
             │   ├─ 382 pcmanfm-qt --desktop --profile=lxqt
             │   ├─ 384 lxqt-globalkeysd
             │   ├─ 385 lxqt-notificationd
             │   ├─ 386 lxqt-panel
             │   ├─ 387 lxqt-policykit-agent
             │   ├─ 389 lxqt-runner
             │   ├─ 391 /usr/bin/xscreensaver -no-splash
             │   ├─ 405 /usr/lib/menu-cache/menu-cached /tmp/.menu-cached-:0-levon
             │   ├─ 409 /usr/lib/gvfs/gvfsd
             │   ├─ 415 /usr/lib/gvfs/gvfsd-fuse /run/user/1000/gvfs -f -o big_writes
             │   ├─ 421 /usr/lib/gvfs/gvfs-udisks2-volume-monitor
             │   ├─ 445 /usr/lib/gvfs/gvfs-gphoto2-volume-monitor
             │   ├─ 449 /usr/lib/gvfs/gvfs-afc-volume-monitor
             │   ├─ 476 lxqt-powermanagement
             │   ├─ 481 /usr/bin/urxvt
             │   ├─ 482 bash
             │   ├─ 725 /usr/bin/firefox
             │   ├─ 746 /usr/lib/at-spi2-core/at-spi-bus-launcher
             │   ├─ 755 /usr/bin/thunderbird
             │   ├─ 810 /usr/lib32/skype/skype
             │   ├─5944 dhclient -v enp0s20u4u1
             │   └─7926 systemctl status --no-pager
             └─user-997.slice
               ├─user@997.service
               │ ├─329 /usr/lib/systemd/systemd --user
               │ └─330 (sd-pam)
               └─session-c1.scope
                 ├─340 dbus-launch --autolaunch 9232fd1708c442da90b2b435d7a91f77 --binary-syntax --close-stderr
                 └─341 /usr/bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session

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#4 2015-09-27 17:18:17

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 20,349

Re: [Solved] Problems with wired connection

Processes 7906 and 5944 will conflict with each other.

Try this.  Stop the netctl@wlp2s0\x2dsvolach service.  (Also, it appears you started that service by hand.  Did you?)
kill 5944 and any other dhcpcd or dhclient services that are running.

Then try just a sudo dhcpcd and see what happens.

Now.  There is something very odd about your network.   You said it is a university, so I am thinking this might be a 10.0.0.0/8 network.  But I note that there are multiple machines on the network acting as DHCP servers.

enp0s20u4u1: offered 10.38.186.129 from 163.1.158.81
enp0s20u4u1: probing static address 10.38.186.129/23
enp0s20u4u1: ignoring offer of 192.168.1.101 from 192.168.1.254
enp0s20u4u1: NAK: wrong server-ID from 192.168.1.254
enp0s20u4u1: message: wrong server-ID
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.101 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.186.129 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81
enp0s20u4u1: message: requested address not available
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.101 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.186.129 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81

So, 163.1.158.81 is offering 10.38.186.129.     192.168.1.254 is offering 192.168.1.101, but you think it has a wrong server-ID, so it is ignored.
Unfortunately, the address 163.1.158.81 offered, 10.38.186.129, is not available.  Your system probed it, but there is a computer out there with that address already.

Do you know what the addressing scheme is supposed to be?  Do you know which is the real DHCP server? 
If 163.1.158.81 insists on that address for you, and someone else is squatting on that address (as a static address), you may be out of luck.   You might have to talk to the IT folk.

The only other thing you might try would be to hand delete your leases and try again


Edit:

Oh, then dhclient

Listening on LPF/enp0s20u4u1/00:e0:4c:b8:03:23
Sending on   LPF/enp0s20u4u1/00:e0:4c:b8:03:23
Sending on   Socket/fallback
DHCPREQUEST on enp0s20u4u1 to 255.255.255.255 port 67
DHCPNAK from 10.38.187.254
DHCPDISCOVER on enp0s20u4u1 to 255.255.255.255 port 67 interval 4
DHCPREQUEST on enp0s20u4u1 to 255.255.255.255 port 67
DHCPOFFER from 192.168.1.254
DHCPNAK from 10.38.187.254
DHCPACK from 192.168.1.254
bound to 192.168.1.101 -- renewal in 39056 seconds.

You did accept an address from 192.168.1.254.  Not from 10.38.187.254. 
I think that  192.168.1.254 is a rogue server that has given you a bogus address and default route.

Last edited by ewaller (2015-09-27 17:23:30)

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#5 2015-09-27 18:07:38

lyovushka
Member
Registered: 2015-09-27
Posts: 5

Re: [Solved] Problems with wired connection

netctl@wlp2s0\x2dsvolach is the service for the wireless network I am currently on. I turn it off every time I try a wired connection. I've tried killing all dhcpcd and dhclient processes before attempting sudo dhcpcd enp0s20u4u1 but I got similar results, i.e. an offer of 10.38.186.129 and a NAK.

I checked the settings on the windows computer. It's DHCP server is 163.1.158.81 and it's IP begins with 10.38. So I'm guessing 10.38.186.129 is the right IP.

Could you please tell me more about hand deleting my leases? I might try that before going to IT people.

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#6 2015-09-27 18:20:51

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 20,349

Re: [Solved] Problems with wired connection

For dhcpcd, the leases are at /var/lib/dhcpcd/    Just delete them from the command line as root.  Before you do, take a look at the names of the files in there.  The names may provide some insight.

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#7 2015-09-27 20:12:51

lyovushka
Member
Registered: 2015-09-27
Posts: 5

Re: [Solved] Problems with wired connection

Things got a bit more interesting here. I checked the directory /var/lib/dhcpcd/ and all the filenames began with dhcpcd-wlp2s0 which is my wireless interface. So I though it wouldn't have any effect but decided to move these files from /var/lib/dhcpcd. To my surprise sudo dhcpcd enp0s20u4u1 then did indeed manage to assign an address, but it was the same address 10.38.186.129. Then I disconnected and tried again. This time I could not get an address. This happened couple of more time and now it is back to not get an address all the time.

Then I figured that if it keeps offering me the same address, it must be because of my mac address. Now the interface enp0s20u4u1 comes from a USB to Ethernet dongle. And I have a spare dongle which would have a different mac address. So I tried this one and indeed I am being offered a different address, but still there is a NAK request.

sudo dhcpcd enp0s20u4u1

DUID 00:01:00:01:1c:7b:a7:72:00:23:56:6c:39:46
enp0s20u4u1: IAID 56:6c:39:46
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.223 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.187.14 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81
enp0s20u4u1: message: requested address not available
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 10.38.187.14 from 163.1.158.81
enp0s20u4u1: probing static address 10.38.187.14/23
enp0s20u4u1: ignoring offer of 192.168.1.223 from 192.168.1.254
enp0s20u4u1: soliciting an IPv6 router
enp0s20u4u1: NAK: wrong server-ID from 192.168.1.254
enp0s20u4u1: message: wrong server-ID
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.223 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.187.14 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81
enp0s20u4u1: message: requested address not available
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.223 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.187.14 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81
enp0s20u4u1: message: requested address not available
enp0s20u4u1: soliciting a DHCP lease
enp0s20u4u1: offered 192.168.1.223 from 192.168.1.254
enp0s20u4u1: ignoring offer of 10.38.187.14 from 163.1.158.81
enp0s20u4u1: NAK: requested address not available from 163.1.158.81
enp0s20u4u1: message: requested address not available

I think it is unlikely that someone is using both of my IP addresses. Could it be that the rogue server at 192.168.1.254 is NAK-ing perfectly good IP addresses? Is there a way to tell dhcpcd to ignore it completely? At the moment I am using the IP address statically and it seems to work fine.

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#8 2015-10-01 19:26:47

lyovushka
Member
Registered: 2015-09-27
Posts: 5

Re: [Solved] Problems with wired connection

It turns out I was getting the same IP not because of my MAC address, but the DHCP Client Identifier. I deleted the file /etc/dhcpcd.duid and now everything works fine. Thanks ewaller for all the help.

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