feat: Allow specifying vmnet network UUID to disable DHCP #140

pallotron · 2025-10-08T10:30:31Z

What

This commit introduces a new --vmnet-network-uuid command-line option to allow setting the vmnet_network_identifier_key for vmnet.

This property is only applicable to a vmnet_interface in VMNET_HOST_MODE.

If this property is set, the vmnet_interface is added to an isolated network with the specified identifier.

No DHCP service is provided on this network.

Why

This is useful for certain applications where the users need an isolated network and are running their own dhcp to assign IPs in such network.

See issue #139

Testing

Printed new --help

❯ make
cc -O3 -Wall -Wextra -pedantic -DVERSION=\"a7cc880.m\" -c cli.c -o cli.o
cc -O3 -Wall -Wextra -pedantic -DVERSION=\"a7cc880.m\" -o socket_vmnet  -framework vmnet cli.o main.o


❯ sudo ./socket_vmnet --help
Usage: ./socket_vmnet [OPTION]... SOCKET
vmnet.framework support for rootless QEMU.
socket_vmnet does not require QEMU to run as the root user, but socket_vmnet itself has to run as the root, in most cases.

--socket-group=GROUP                socket group name (default: "staff")
--vmnet-mode=(host|shared|bridged)  vmnet mode (default: "shared")
--vmnet-interface=INTERFACE         interface used for --vmnet=bridged, e.g., "en0"
--vmnet-gateway=IP                  gateway used for --vmnet=(host|shared), e.g., "192.168.105.1" (default: decided by macOS)
                                    the next IP (e.g., "192.168.105.2") is used as the first DHCP address
--vmnet-dhcp-end=IP                 end of the DHCP range (default: XXX.XXX.XXX.254)
                                    requires --vmnet-gateway to be specified
--vmnet-mask=MASK                   subnet mask (default: "255.255.255.0")
                                    requires --vmnet-gateway to be specified
--vmnet-interface-id=UUID           vmnet interface ID (default: random)
--vmnet-network-identifier=UUID     vmnet network identifier (UUID string, "random", or "")
                                    When vmnet mode is "host" and --vmnet-gateway is not set, the internal DHCP will be disabled.
                                    (default: "random")
--vmnet-nat66-prefix=PREFIX::       The IPv6 prefix to use with shared mode.
                                    The prefix must be a ULA i.e. start with fd00::/8.
                                    (default: random)
-p, --pidfile=PIDFILE               save pid to PIDFILE
-h, --help                          display this help and exit
-v, --version                       display version information and exit

version: a7cc880.m

Ran locally in host mode w/p network UUID provided -> DHCP enabled, backward compatible

❯ sudo ./socket_vmnet "/opt/homebrew/var/run/socket_vmnet" --vmnet-mode=host
INFO | Initializing vmnet.framework (mode 1000)
INFO | * vmnet_write_max_packets: 256
INFO | * vmnet_read_max_packets: 256
INFO | * vmnet_subnet_mask: 255.255.255.0
INFO | * vmnet_mtu: 1500
INFO | * vmnet_end_address: 192.168.111.254
INFO | * vmnet_start_address: 192.168.111.1
INFO | * vmnet_interface_id: 493B7D05-7098-462E-A535-9A09E9F23015
INFO | * vmnet_max_packet_size: 1514
INFO | * vmnet_mac_address: be:03:14:a1:76:2f

Ran locally in shared mode -> DHCP enabled, backward compatible

❯ sudo ./socket_vmnet "/opt/homebrew/var/run/socket_vmnet" --vmnet-gateway=192.168.111.1
INFO | Initializing vmnet.framework (mode 1001)
INFO | * vmnet_write_max_packets: 256
INFO | * vmnet_read_max_packets: 256
INFO | * vmnet_subnet_mask: 255.255.255.0
INFO | * vmnet_mtu: 1500
INFO | * vmnet_end_address: 192.168.111.254
INFO | * vmnet_start_address: 192.168.111.1
INFO | * vmnet_interface_id: 7C36E6A4-9462-41C1-9102-32052F371566
INFO | * vmnet_max_packet_size: 1514
INFO | * vmnet_nat66_prefix: fd44:1114:5237:b1c3::
INFO | * vmnet_mac_address: c6:fd:21:f7:7d:52

Ran local in host mode + random network identifier: no dhcp, new behavior

❯ sudo ./socket_vmnet "/opt/homebrew/var/run/socket_vmnet" --vmnet-mode=host --vmnet-network-identifier=random
INFO | Initializing vmnet.framework (mode 1000)
INFO | Using network identifier "BBE66D8F-61C8-4393-82F8-7FAE5FE9706D" and no vmnet gateway -> NO DHCP will be enabled on this vmnet
INFO | * vmnet_write_max_packets: 256
INFO | * vmnet_read_max_packets: 256
INFO | * vmnet_subnet_mask: 0.0.0.0
INFO | * vmnet_mtu: 1500
INFO | * vmnet_end_address: 255.255.255.254
INFO | * vmnet_start_address: 0.0.0.0
INFO | * vmnet_interface_id: 98B26815-84E6-4064-98B5-EB9D21A91082
INFO | * vmnet_max_packet_size: 1514
INFO | * vmnet_mac_address: e6:ce:e1:2a:75:af

pallotron · 2025-10-08T14:23:56Z

let me know if you want to create a correspondent io.github.lima-vm.socket_vmnet.host_dhcp.plist in launchd/ and relative modications to the Makefile.

pallotron · 2025-10-10T07:56:16Z

@AkihiroSuda hey can you guys let me know what you think of this when you get a chance? :)

AkihiroSuda · 2025-10-10T08:09:21Z

Thanks, but please sign the commit for DCO
https://github.com/apps/dco

(run git commit -a -s --amend, and make sure that the Signed-off-by: NAME <EMAIL> line with your real name is included in the commit message)

cli.h

README.md

pallotron

thanks for the comments, and sorry about the signature mishap.
I was using my corporate laptop and the setup there is a bit messy. Will fix.

pallotron · 2025-10-10T09:37:23Z

Thanks, but please sign the commit for DCO https://github.com/apps/dco

(run git commit -a -s --amend, and make sure that the Signed-off-by: NAME <EMAIL> line with your real name is included in the commit message)

I think my commits are all good yet but I dunno why DCO is failing now :(

pallotron · 2025-10-10T09:46:17Z

my last commit has the sign-off but I dunno why DCO is failing... :(
do I need to squash all commits?

commit f7bdb95a66ed3093ac5893e41a373a357bb945fc (HEAD -> feature/no_dhcp_issue_139, origin/feature/no_dhcp_issue_139)
Good "git" signature for pallotron@gmail.com with ED25519 key SHA256:bCGybCKH6mAgRuXgyjQSoTKIlRJOyIxRny1Gmg/3MmI
Author: Angelo Failla <pallotron@gmail.com>
Date:   Fri Oct 10 10:26:15 2025 +0100

    fix comment as per review

    Signed-off-by: Angelo Failla <pallotron@gmail.com>

commit f912515d2d431d939f5a77afcf073cdfd99ef4ec
Good "git" signature for pallotron@gmail.com with ED25519 key SHA256:bCGybCKH6mAgRuXgyjQSoTKIlRJOyIxRny1Gmg/3MmI
Author: Angelo Failla <pallotron@gmail.com>
Date:   Thu Oct 9 08:27:13 2025 +0100

    Better logic + esplicitely printing when DHCP is going to be disabled

commit 20d8ee1e7aac111c6329f90bfa876ffe26488769
Good "git" signature for pallotron@gmail.com with ED25519 key SHA256:bCGybCKH6mAgRuXgyjQSoTKIlRJOyIxRny1Gmg/3MmI
Author: Angelo Failla <pallotron@gmail.com>
Date:   Wed Oct 8 16:22:03 2025 +0100

    README.md: add some explanation

AkihiroSuda · 2025-10-10T09:47:29Z

squash

Yes, please
https://lima-vm.io/docs/dev/git/#squashing-commits

pallotron · 2025-10-10T09:50:33Z

ok I fixed DCO, squashes all commits and made sure there is sign off.

cli.h

AkihiroSuda

Looks like a breaking change

#140 (comment)

…ost network only) This commit introduces a new `--vmnet-network-uuid` command-line option to allow setting the `vmnet_network_identifier_key` for vmnet. This property is only applicable to a vmnet_interface in VMNET_HOST_MODE. If this property is set, the vmnet_interface is added to an isolated network with the specified identifier. No DHCP service is provided on this network. This is useful for certain applications where the users need an isolated network and are running their own dhcp to assign IPs in such network. See issue [lima-vm#139](lima-vm#139) Signed-off-by: Angelo (pallotron) Failla <pallotron@gmail.com>

AkihiroSuda · 2025-10-11T08:10:37Z

README.md

-  - [IP address is not assigned](#ip-address-is-not-assigned)
- [Links](#links)
- [Troubleshooting](#troubleshooting)
+- [socket_vmnet: vmnet.framework support for rootless and VDE-less QEMU](#socket_vmnet-vmnetframework-support-for-rootless-and-vde-less-qemu)


AkihiroSuda · 2025-10-11T08:10:42Z

README.md


-> [!TIP]
-> `sudo make install` is also available in addition to `sudo make install.bin`.
+> [!TIP] > `sudo make install` is also available in addition to `sudo make install.bin`.


AkihiroSuda · 2025-10-11T08:11:12Z

README.md

+- Create a host network where all VMs have static IPs.
+- Run a custom DHCP server on one VM to assign IPs to others on the same network.
+
+To disable the MacOS DHCP you must use `--vmnet-mode=host` and provide a `--vmnet-network-idenfitier` UUID.


Suggested change

To disable the MacOS DHCP you must use `--vmnet-mode=host` and provide a `--vmnet-network-idenfitier` UUID.

To disable the macOS DHCP you must use `--vmnet-mode=host` and provide a `--vmnet-network-idenfitier` UUID.

AkihiroSuda · 2025-10-11T08:12:04Z

cli.c

+         "or \"\")\n"
+         "                                    When vmnet mode is \"host\" and --vmnet-gateway is "
+         "not set, the internal DHCP will be disabled.\n"
+         "                                    (default: \"random\")\n");


default should be an empty string

pallotron · 2025-10-11T08:18:43Z

made a mess with jj started a clean PR in #141

pallotron changed the title ~~feat: Allow specifying vmnet network UUID to disable DHCP (on vmnet.h…~~ feat: Allow specifying vmnet network UUID to disable DHCP Oct 8, 2025

pallotron force-pushed the feature/no_dhcp_issue_139 branch 6 times, most recently from c49d5b0 to 9de6fa5 Compare October 8, 2025 11:01

pallotron force-pushed the feature/no_dhcp_issue_139 branch 7 times, most recently from df1f00b to f912515 Compare October 9, 2025 08:03

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AkihiroSuda added this to the v1.2.2 milestone Oct 10, 2025

AkihiroSuda linked an issue Oct 10, 2025 that may be closed by this pull request

Feature Request: Support for disabling DHCP on vmnet-host networks #139

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pallotron commented Oct 10, 2025

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pallotron deleted the feature/no_dhcp_issue_139 branch October 11, 2025 08:16

pallotron restored the feature/no_dhcp_issue_139 branch October 11, 2025 08:17

AkihiroSuda removed this from the v1.2.2 milestone Oct 11, 2025

	To disable the MacOS DHCP you must use `--vmnet-mode=host` and provide a `--vmnet-network-idenfitier` UUID.
	To disable the macOS DHCP you must use `--vmnet-mode=host` and provide a `--vmnet-network-idenfitier` UUID.

feat: Allow specifying vmnet network UUID to disable DHCP #140

feat: Allow specifying vmnet network UUID to disable DHCP #140

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What

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Testing

Printed new --help

Ran locally in host mode w/p network UUID provided -> DHCP enabled, backward compatible

Ran locally in shared mode -> DHCP enabled, backward compatible

Ran local in host mode + random network identifier: no dhcp, new behavior

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