network/dhcp: add IPv6 only mode support #29472

yuwata · 2023-10-06T05:57:23Z

split-out of #29063.
replaces #28950.

yuwata · 2023-10-06T10:29:10Z

@ssahani Sorry for late. Finally I added several test cases. The basic implementation for DHCP server side is equivalent to yours. But the implementation for the client side is quite different. Please take a look.

ssahani · 2023-10-07T08:45:38Z

Looks pretty good. Thanks a ton working on this.

yuwata · 2023-10-07T12:37:30Z

CentOS CI failure is unrelated (TEST-50-DISSECT).

src/libsystemd-network/dhcp-protocol.h

src/libsystemd-network/sd-dhcp-server.c

src/libsystemd-network/sd-dhcp-client.c

yuwata · 2023-10-11T06:14:56Z

@poettering Thank you for the review. Addressed the above suggestions. Upgrading the green label.

This makes sd-dhcp-server send IPv6 only preferred option (RFC 8925). Co-authored-by: Yu Watanabe <[email protected]>

Co-authored-by: Yu Watanabe <[email protected]>

This makes sd-dhcp-client optionally request IPv6 only preferred option (RFC 8925).

Co-authored-by: Susant Sahani <[email protected]>

For [DHCPv4] IPv6OnlyMode= and [DHCPServer] IPv6OnlyPreferredSec=.

evverx · 2023-10-12T07:37:54Z

Looks like in IPv6-only mode networkctl renew iface leads to assert_return

systemd-networkd[350]: Assertion 'sd_dhcp_client_is_running(client)' failed at src/libsystemd-network/sd-dhcp-client.c:2158, function sd_dhcp_client_send_renew(). Ignoring.

It's expected that it should fail but I'm not sure it should look like this.

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd#29472 (comment).

yuwata · 2023-10-12T09:41:04Z

@evverx Thanks. Fix is waiting in #29544.

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd/systemd#29472 (comment). (cherry picked from commit 9bd91e3)

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd/systemd#29472 (comment). (cherry picked from commit 9bd91e3) (cherry picked from commit f453cbc)

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd/systemd#29472 (comment). (cherry picked from commit 9bd91e3) (cherry picked from commit f453cbc) (cherry picked from commit 073d2db)

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd#29472 (comment).

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd/systemd#29472 (comment). (cherry picked from commit 9bd91e3) (cherry picked from commit f453cbc) (cherry picked from commit 073d2db)

Leseratte10 · 2023-12-30T09:02:56Z

As I already commented over at #23674 , I'm not 100% sure if this current implementation matches the RFC8925 spec.

The RFC says that this parameter should be sent by "IPv6-only-capable hosts", and defines that term with the following description:

IPv6-only-capable host: A host that does not require an IPv4 address and can operate on IPv6-only networks. More precisely, IPv6-only capability is specific to a given interface of the host: if some applications on a host require IPv4 and the 464XLAT CLAT (customer-side translator) [RFC6877] is only enabled on one interface, the host is IPv6-only capable if connected to a NAT64 network via that interface.

This sounds to me like this flag should only be advertised on hosts that are only running IPv6-capable software, or on hosts running a 464XLAT (#23674). By turning this flag on by default, this means that any Linux machine with systemd, running in a network that uses / supports that flag, the Linux machine will not request an IPv4 from the DHCP server, breaking all functionality for IPv4-only applications.

According to the RFC, if I'm interpreting it correctly, this parameter should only be sent when there's a working 464XLAT (or when the administrator is 100% sure there's only IPv6-capable software on the machine and manually turns it on, but not by default). Can this be updated to switch the default value for IPv6OnlyMode back to False until 464XLAT is implemented and available?

yuwata added network tests dhcp labels Oct 6, 2023

github-actions bot added the documentation label Oct 6, 2023

This was referenced Oct 6, 2023

network: introduce test mode #29470

Merged

test-network: move get_dbus_dhcp_client_state() and friends to global #29471

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yuwata force-pushed the network-dhcp-ipv6-only-mode branch from 9ed7a5f to bfe58e2 Compare October 6, 2023 09:52

yuwata force-pushed the network-dhcp-ipv6-only-mode branch 2 times, most recently from 8b28148 to 51a8394 Compare October 6, 2023 13:04

yuwata marked this pull request as ready for review October 6, 2023 13:15

yuwata added new-feature please-review PR is ready for (re-)review by a maintainer labels Oct 6, 2023

yuwata force-pushed the network-dhcp-ipv6-only-mode branch 2 times, most recently from dbacd59 to bd095ff Compare October 7, 2023 06:27

yuwata force-pushed the network-dhcp-ipv6-only-mode branch from bd095ff to 38e24d5 Compare October 9, 2023 05:32

poettering reviewed Oct 9, 2023

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poettering added good-to-merge/with-minor-suggestions and removed please-review PR is ready for (re-)review by a maintainer labels Oct 9, 2023

yuwata force-pushed the network-dhcp-ipv6-only-mode branch from 38e24d5 to 4094215 Compare October 11, 2023 06:14

yuwata added good-to-merge/waiting-for-ci 👍 PR is good to merge, but CI hasn't passed at time of review. Please merge if you see CI has passed and removed good-to-merge/with-minor-suggestions labels Oct 11, 2023

bluca added ci-fails/needs-rework 🔥 Please rework this, the CI noticed an issue with the PR and removed good-to-merge/waiting-for-ci 👍 PR is good to merge, but CI hasn't passed at time of review. Please merge if you see CI has passed labels Oct 11, 2023

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ssahani and others added 5 commits October 11, 2023 21:42

sd-dhcp-server: support IPv6 only mode

14bd102

This makes sd-dhcp-server send IPv6 only preferred option (RFC 8925). Co-authored-by: Yu Watanabe <[email protected]>

network/dhcp-server: allow to configure IPv6 only preferred option

34bea0a

Co-authored-by: Yu Watanabe <[email protected]>

sd-dhcp-client: support IPv6 only mode

a91b888

This makes sd-dhcp-client optionally request IPv6 only preferred option (RFC 8925).

network/dhcp4: support IPv6 only mode (RFC 8925)

fc35a9f

Co-authored-by: Susant Sahani <[email protected]>

test-network: add tests for DHCP IPv6 only mode

46f2eb5

For [DHCPv4] IPv6OnlyMode= and [DHCPServer] IPv6OnlyPreferredSec=.

yuwata force-pushed the network-dhcp-ipv6-only-mode branch 2 times, most recently from 2b06738 to 46f2eb5 Compare October 11, 2023 12:48

yuwata merged commit 9a551cc into systemd:main Oct 12, 2023
46 checks passed

yuwata deleted the network-dhcp-ipv6-only-mode branch October 12, 2023 04:06

github-actions bot removed the good-to-merge/waiting-for-ci 👍 PR is good to merge, but CI hasn't passed at time of review. Please merge if you see CI has passed label Oct 12, 2023

yuwata added a commit to yuwata/systemd that referenced this pull request Oct 12, 2023

network: restart dhcp4 client when renewing lease is requested but th…

9bd91e3

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd#29472 (comment).

yuwata mentioned this pull request Oct 12, 2023

network: several fixlets for DBus methods for DHCP client and server #29544

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zajdee mentioned this pull request Oct 22, 2023

464XLAT support #23674

Open

ssahani pushed a commit to ssahani/systemd that referenced this pull request Nov 23, 2023

network: restart dhcp4 client when renewing lease is requested but th…

acde83f

…e client is stopped Follow-up for fc35a9f. Fixes the issue systemd#29472 (comment).

pemensik mentioned this pull request Dec 6, 2023

Please support RFC 8925 IPv6-Only Preferred Option for DHCPv4 (Option 108) #24624

Closed

Leseratte10 mentioned this pull request Jan 11, 2024

network/dhcp: RFC8925 violation (IPv6OnlyMode) resulting in broken IPv4 in IPv6-preferring networks #30891

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network/dhcp: add IPv6 only mode support #29472

network/dhcp: add IPv6 only mode support #29472

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network/dhcp: add IPv6 only mode support #29472

network/dhcp: add IPv6 only mode support #29472

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