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Bug 1861488 - [RHEL 8.2] Can not configure a DHCP Address
Summary: [RHEL 8.2] Can not configure a DHCP Address
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: NetworkManager
Version: ---
Hardware: s390x
OS: Linux
unspecified
medium
Target Milestone: rc
: 8.0
Assignee: Beniamino Galvani
QA Contact: Desktop QE
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2020-07-28 17:54 UTC by Thiago Sales
Modified: 2023-12-15 18:40 UTC (History)
10 users (show)

Fixed In Version: NetworkManager-1.26.0-3.el8
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2020-11-04 01:47:57 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker NMT-1000 0 None None None 2023-12-15 18:40:16 UTC

Description Thiago Sales 2020-07-28 17:54:28 UTC 
Description of problem:

After the upgrade the system from RHEL 8.1 4.18.0-147 to RHEL 8.2 4.18.0-193 or 4.18.0-222.el8.s390x, the NetworkManager can not get a DHCP Address for the interface.

If we configure the file "/etc/NetworkManager/NetworkManager.conf" with the parameter dhcp=dhclient under the key [main]:

# cat /etc/NetworkManager/NetworkManager.conf
[main]
dhcp=dhclient

When we set NetworkManager to use dhclient the server can configure the IPV4 on the interface.
Also, if we use the network.service instead of NetworkManager the server will configure the IPv4 address in the interface normally.

The issue only reproduce using NetworkManager.


Version-Release number of selected component (if applicable):

First scenario that the problem occurred:

RHEL 8.2 4.18.0-193.1.2.el8_2.s390x
NetworkManager-1.22.8-4.el8.s390x                           Wed Jun 24 11:59:56 2020
NetworkManager-libnm-1.22.8-4.el8.s390x                     Wed Jun 24 11:59:56 2020
NetworkManager-team-1.22.8-4.el8.s390x                      Wed Jun 24 12:00:15 2020
NetworkManager-tui-1.22.8-4.el8.s390x                       Wed Jun 24 12:00:16 2020
dracut-network-049-70.git20200228.el8.s390x                 Wed Jun 24 12:00:07 2020
network-scripts-10.00.6-1.el8.s390x                         Wed Jun 24 11:59:48 2020
network-scripts-team-1.29-1.el8.s390x                       Wed Jun 24 12:00:00 2020

Second scenario that the problem occurred:

RHEL 8 devel kernel 4.18.0-222.el8.s390x
NetworkManager-1.22.8-5.el8_2.s390x                         Wed Jul 15 08:28:32 2020
NetworkManager-config-server-1.22.8-5.el8_2.noarch          Wed Jul 15 08:28:32 2020
NetworkManager-libnm-1.22.8-5.el8_2.s390x                   Wed Jul 15 08:28:31 2020
NetworkManager-team-1.22.8-5.el8_2.s390x                    Wed Jul 15 08:28:32 2020
NetworkManager-tui-1.22.8-5.el8_2.s390x                     Wed Jul 15 08:28:32 2020
dracut-network-049-70.git20200228.el8.s390x                 Tue Jun 30 13:16:14 2020
network-scripts-10.00.6-1.el8.s390x                         Tue Jun 30 13:15:53 2020
network-scripts-team-1.29-1.el8.s390x                       Tue Jun 30 13:16:05 2020

How reproducible:

Upgrade the RHEL 8.1 4.18.0-147.5.1.el8_1.s390x to RHEL 8.2 4.18.0-193.1.2.el8_2.s390x or later

Steps to Reproduce:
1. Upgrade the RHEL 8.1 4.18.0-147.5.1.el8_1.s390x to RHEL 8.2 4.18.0-193.1.2.el8_2.s390x or later
2. Reboot the system
3. The server will start and won't get a DHCP Address

Actual results:

The customer is work around the using:
# cat /etc/NetworkManager/NetworkManager.conf
[main]
dhcp=dhclient


Expected results:
As the network.service will be deprecated the customer expect to get a DHCP using NetworkManager.

Additional info:

In the beginning we think that this was the same issue as in BZ 1843357 - NetworkManager doesn't reconnect after DHCP failure [rhel-8.2.0.z]. But is not, this is a different issue.

Attach in this BZ the "/var/log/messages" and "/var/log/dmesg" file from the server.
Comment 3 Thomas Haller 2020-07-28 21:11:07 UTC 
in the SOS report at https://access.redhat.com/support/cases/#/case/02682336?attachmentId=a092K000025It8IQAS , in file [1] we see how the internal/nettools DHCP client is used.

We see that the client repeatedly sends 

  dhcp4 (enc350): send DISCOVER to 255.255.255.255

without reply.

[1] ./sos_commands/logs/journalctl_--no-pager_--catalog_--boot



From the provided information, it cannot be seen why it wouldn't work.

Please capture a package trace, with tcpdump. You don't need to reboot, just start run tcpdump while reactivating the profile (and wait long enough, to see whether there are any responses).

  tcpdump -s 0 -i any -w /tmp/my-capture.pcap



Since the difference is apparently the DHCP implementation, it would be most helpful to retry this also with the dhclient plugin.



Btw, the dhclient plugin is still fully supported. So, it is a reasonable workaround to use dhcp=dhclient in this case.
Comment 4 Thiago Sales 2020-07-30 12:56:15 UTC 
(In reply to Thomas Haller from comment #3)
> in the SOS report at
> https://access.redhat.com/support/cases/#/case/
> 02682336?attachmentId=a092K000025It8IQAS , in file [1] we see how the
> internal/nettools DHCP client is used.
> 
> We see that the client repeatedly sends 
> 
>   dhcp4 (enc350): send DISCOVER to 255.255.255.255
> 
> without reply.
> 
> [1] ./sos_commands/logs/journalctl_--no-pager_--catalog_--boot
> 
> 
> 
> From the provided information, it cannot be seen why it wouldn't work.
> 
> Please capture a package trace, with tcpdump. You don't need to reboot, just
> start run tcpdump while reactivating the profile (and wait long enough, to
> see whether there are any responses).
> 
>   tcpdump -s 0 -i any -w /tmp/my-capture.pcap
> 
> 
> 
> Since the difference is apparently the DHCP implementation, it would be most
> helpful to retry this also with the dhclient plugin.
> 
> 
> 
> Btw, the dhclient plugin is still fully supported. So, it is a reasonable
> workaround to use dhcp=dhclient in this case.


Hi I'm attaching the captures in the BZ.
Comment 6 Thomas Haller 2020-07-30 15:35:39 UTC 
Thanks Thiago.

The package trace shows that the server sends DHCP offers. By looking at the capture, I don't see anything wrong with it, which would cause the DHCP client to reject the packets. I'll ask Beniamino for his opinion.

You already established that dhclient works. Did you ever test `dhcp=systemd` plugin in that environment? Does that implementation work? That would be interesting to know, to have some comparison.
Comment 7 Beniamino Galvani 2020-08-03 18:35:36 UTC 
Fix for the internal DHCP client:

https://github.com/nettools/n-dhcp4/pull/19
Comment 8 Beniamino Galvani 2020-08-04 15:00:24 UTC 
Hi, we found an issue in the internal DHCP client and pushed a fix upstream. Until the fix reaches RHEL, you should switch to dhcp=dhclient.
Comment 21 errata-xmlrpc 2020-11-04 01:47:57 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (NetworkManager bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:4499
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