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feat: Allow specifying vmnet network UUID to disable DHCP (when in Host mode) #141

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57 changes: 36 additions & 21 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -12,27 +12,28 @@ Unlike `vde_vmnet`, `socket_vmnet` does not depend on VDE.
<!-- START doctoc generated TOC please keep comment here to allow auto update -->
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Install](#install)
- [From binary](#from-binary)
- [From source](#from-source)
- [From Homebrew](#from-homebrew)
- [From MacPorts](#from-macports)
- [Usage](#usage)
- [QEMU](#qemu)
- [Lima](#lima)
- [Advanced usage](#advanced-usage)
- [Multi VM](#multi-vm)
- [Bridged mode](#bridged-mode)
- [FAQs](#faqs)
- [Why does `socket_vmnet` require root?](#why-does-socket_vmnet-require-root)
- [Is it possible to run `socket_vmnet` with SETUID?](#is-it-possible-to-run-socket_vmnet-with-setuid)
- [Install](#install)
- [From binary](#from-binary)
- [From source](#from-source)
- [From Homebrew](#from-homebrew)
- [From MacPorts](#from-macports)
- [Usage](#usage)
- [QEMU](#qemu)
- [Lima](#lima)
- [Advanced usage](#advanced-usage)
- [Multi VM](#multi-vm)
- [Bridged mode](#bridged-mode)
- [FAQs](#faqs)
- [Why does `socket_vmnet` require root?](#why-does-socket_vmnet-require-root)
- [Is it possible to run `socket_vmnet` with SETUID?](#is-it-possible-to-run-socket_vmnet-with-setuid)
- [How is socket_vmnet related to vde_vmnet?](#how-is-socket_vmnet-related-to-vde_vmnet)
- [How is socket_vmnet related to QEMU-builtin vmnet support?](#how-is-socket_vmnet-related-to-qemu-builtin-vmnet-support)
- [How to use static IP addresses?](#how-to-use-static-ip-addresses)
- [How to reserve DHCP addresses?](#how-to-reserve-dhcp-addresses)
- [IP address is not assigned](#ip-address-is-not-assigned)
- [Links](#links)
- [Troubleshooting](#troubleshooting)
- [How is socket_vmnet related to QEMU-builtin vmnet support?](#how-is-socket_vmnet-related-to-qemu-builtin-vmnet-support)
- [How to use static IP addresses?](#how-to-use-static-ip-addresses)
- [How to reserve DHCP addresses?](#how-to-reserve-dhcp-addresses)
- [IP address is not assigned](#ip-address-is-not-assigned)
- [How to setup a vmnet host network without DHCP?](#how-to-setup-a-vmnet-host-network-without-dhcp)
- [Links](#links)
- [Troubleshooting](#troubleshooting)

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@nirs nirs Oct 16, 2025

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The new toc looks wrong. This was not part of the top before:

- [socket_vmnet: vmnet.framework support for rootless and VDE-less QEMU](#socket_vmnet-vmnetframework-support-for-rootless-and-vde-less-qemu)

And the rest of the options are over indented now.

You should should be only:

+ - [How to setup a vmnet host network without DHCP?](#how-to-setup-a-vmnet-host-network-without-dhcp)

Maybe the instructions for running doctor are not correct, or you are running a different version?

Lets separate the README.md change to another PR. We ned to find how to update the README.md without adding unwanted changes.

<!-- END doctoc generated TOC please keep comment here to allow auto update -->

Expand Down Expand Up @@ -122,7 +123,7 @@ Run the following command to start the daemon:
sudo /opt/socket_vmnet/bin/socket_vmnet --vmnet-gateway=192.168.105.1 /var/run/socket_vmnet
```

> [!TIP]
> [!TIP]
> `sudo make install` is also available in addition to `sudo make install.bin`.
> The former one installs the launchd service (see below) too.

Expand Down Expand Up @@ -430,6 +431,20 @@ sudo /usr/libexec/ApplicationFirewall/socketfilterfw --add /usr/libexec/bootpd
/usr/libexec/ApplicationFirewall/socketfilterfw --unblock /usr/libexec/bootpd
```

### How to setup a vmnet host network without DHCP?

Some users may need to disable the vmnet framework's DHCP for various scenarios, such as:

- 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.

Disabling macOS DHCP only works in `--vmnet-mode=host` if you provide a `--vmnet-network-idenfitier`.
For example, to create a host network without DHCP on `socket_vmnet`:

```bash
sudo /opt/socket_vmnet/bin/socket_vmnet --vmnet-mode=host --vmnet-network-identifier=$(uuidgen)
```

## Links

- https://developer.apple.com/documentation/vmnet
Expand Down
40 changes: 27 additions & 13 deletions cli.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,12 @@ static void print_usage(const char *argv0) {
"specified\n");
printf("--vmnet-interface-id=UUID vmnet interface ID (default: "
"random)\n");
printf("--vmnet-network-identifier=UUID The identifier(uuid) to uniquely identify the network. \n"
" This property is only applicable to a vmnet_interface\n"
" in VMNET_HOST_MODE.\n"
" If this property is set, the vmnet_interface is added to \n"
" an isolated network with the specified\n"
" identifier. No DHCP service is provided on this network.\n");
printf("--vmnet-nat66-prefix=PREFIX:: The IPv6 prefix to use with "
"shared mode.\n");
printf(" The prefix must be a ULA i.e. "
Expand All @@ -72,6 +78,7 @@ enum {
CLI_OPT_VMNET_MASK,
CLI_OPT_VMNET_INTERFACE_ID,
CLI_OPT_VMNET_NAT66_PREFIX,
CLI_OPT_VMNET_NETWORK_IDENTIFIER,
};

struct cli_options *cli_options_parse(int argc, char *argv[]) {
Expand All @@ -82,18 +89,19 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
}

const struct option longopts[] = {
{"socket-group", required_argument, NULL, CLI_OPT_SOCKET_GROUP },
{"vmnet-mode", required_argument, NULL, CLI_OPT_VMNET_MODE },
{"vmnet-interface", required_argument, NULL, CLI_OPT_VMNET_INTERFACE },
{"vmnet-gateway", required_argument, NULL, CLI_OPT_VMNET_GATEWAY },
{"vmnet-dhcp-end", required_argument, NULL, CLI_OPT_VMNET_DHCP_END },
{"vmnet-mask", required_argument, NULL, CLI_OPT_VMNET_MASK },
{"vmnet-interface-id", required_argument, NULL, CLI_OPT_VMNET_INTERFACE_ID},
{"vmnet-nat66-prefix", required_argument, NULL, CLI_OPT_VMNET_NAT66_PREFIX},
{"pidfile", required_argument, NULL, 'p' },
{"help", no_argument, NULL, 'h' },
{"version", no_argument, NULL, 'v' },
{0, 0, 0, 0 },
{"socket-group", required_argument, NULL, CLI_OPT_SOCKET_GROUP },
{"vmnet-mode", required_argument, NULL, CLI_OPT_VMNET_MODE },
{"vmnet-interface", required_argument, NULL, CLI_OPT_VMNET_INTERFACE },
{"vmnet-gateway", required_argument, NULL, CLI_OPT_VMNET_GATEWAY },
{"vmnet-dhcp-end", required_argument, NULL, CLI_OPT_VMNET_DHCP_END },
{"vmnet-mask", required_argument, NULL, CLI_OPT_VMNET_MASK },
{"vmnet-interface-id", required_argument, NULL, CLI_OPT_VMNET_INTERFACE_ID },
{"vmnet-nat66-prefix", required_argument, NULL, CLI_OPT_VMNET_NAT66_PREFIX },
{"vmnet-network-identifier", required_argument, NULL, CLI_OPT_VMNET_NETWORK_IDENTIFIER},
{"pidfile", required_argument, NULL, 'p' },
{"help", no_argument, NULL, 'h' },
{"version", no_argument, NULL, 'v' },
{0, 0, 0, 0 },
};
int opt = 0;
while ((opt = getopt_long(argc, argv, "hvp:", longopts, NULL)) != -1) {
Expand Down Expand Up @@ -134,6 +142,12 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
case CLI_OPT_VMNET_NAT66_PREFIX:
res->vmnet_nat66_prefix = strdup(optarg);
break;
case CLI_OPT_VMNET_NETWORK_IDENTIFIER:
if (uuid_parse(optarg, res->vmnet_network_identifier) < 0) {
ERRORF("Failed to parse network identifier UUID \"%s\"", optarg);
goto error;
}
break;
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@nirs nirs Oct 16, 2025

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Lets replace the section with:

    case CLI_OPT_VMNET_NETWORK_IDENTIFIER:
        if (uuid_parse(optarg, res->vmnet_network_identifier) < 0) {
            ERRORF("Failed to parse UUID \"%s\"", optarg);
            goto error;
        }
        break;

case 'p':
res->pidfile = strdup(optarg);
break;
Expand Down Expand Up @@ -191,7 +205,7 @@ struct cli_options *cli_options_parse(int argc, char *argv[]) {
goto error;
}
if (res->vmnet_gateway == NULL) {
if (res->vmnet_mode != VMNET_BRIDGED_MODE) {
if (res->vmnet_mode != VMNET_BRIDGED_MODE && res->vmnet_mode != VMNET_HOST_MODE) {
WARN("--vmnet-gateway=IP should be explicitly specified to "
"avoid conflicting with other applications");
}
Expand Down
2 changes: 2 additions & 0 deletions cli.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ struct cli_options {
char *vmnet_mask;
// --vmnet-interface-id, corresponds to vmnet_interface_id_key
uuid_t vmnet_interface_id;
// --vmnet-network-identifier, corresponds to vmnet_network_identifier_key
uuid_t vmnet_network_identifier;
// --vmnet-nat66-prefix, corresponds to vmnet_nat66_prefix_key
char *vmnet_nat66_prefix;
// -p, --pidfile; writes pidfile using permissions of socket_vmnet
Expand Down
5 changes: 5 additions & 0 deletions main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -230,6 +230,11 @@ static interface_ref start(struct state *state, struct cli_options *cliopt) {
INFOF("Using network interface \"%s\"", cliopt->vmnet_interface);
xpc_dictionary_set_string(dict, vmnet_shared_interface_name_key, cliopt->vmnet_interface);
}

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@nirs nirs Oct 16, 2025

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It will be better to keep the block setting the gateway address as is. vmnet docs do not mention that you must not use gateway address and network identifier together, and the purpose of the new flag is not to disable DHCP, but to expose additional vment option, that can be used to disable DHCP.

if (!uuid_is_null(cliopt->vmnet_network_identifier)) {
xpc_dictionary_set_uuid(dict, vmnet_network_identifier_key, cliopt->vmnet_network_identifier);
}

if (cliopt->vmnet_gateway != NULL) {
xpc_dictionary_set_string(dict, vmnet_start_address_key, cliopt->vmnet_gateway);
xpc_dictionary_set_string(dict, vmnet_end_address_key, cliopt->vmnet_dhcp_end);
Expand Down