Read port forwards from per-VM forwards.conf files

A QEMU config file section cannot hold more than one hostfwd entry, so
the forwards move out of the ini files into qemu/<vm>/forwards.conf, one
"LABEL HOST_PORT GUEST_PORT" rule per line. The new vmforwards.py parses
them, skips rules whose host port is taken and builds the -netdev
argument, which every launcher now passes instead of relying on a
netdev section in the ini or on -nic.

The ini files move to qemu/<vm>/config.ini and qemu/<vm>/<os>-<arch>.ini.
The *_SSH_PORT / *_RDP_PORT variables and --rdp-port / --ssh-port still
replace the host port of the SSH and RDP rules.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

README.md

@@ -26,12 +26,12 @@ original qcow2 image as its backing file. The base image therefore stays
 unchanged. Run `./run-debian13.py --help` for the supported environment
 variables.
 
-The Debian VM hardware (8G memory, 8 CPUs, drives, network) is
+The Debian VM hardware (8G memory, 8 CPUs, drives) is
-defined in the QEMU config file `qemu/debian13.ini`; the machine type and
+defined in the QEMU config file `qemu/debian13/config.ini`; the machine type and
-architecture-specific devices are in `qemu/debian13-<os>-<arch>.ini`
+architecture-specific devices are in `qemu/debian13/<os>-<arch>.ini`
 (os `linux` or `darwin`, arch `amd64` or `arm64`), together with the
 accelerators. Edit these files to change the settings. The
-launcher fills in the `${...}` file path placeholders of `qemu/debian13.ini`,
+launcher fills in the `${...}` file path placeholders of `qemu/debian13/config.ini`,
 writes the result to `vm/debian13/qemu.ini` and starts QEMU with
 `-readconfig` for that file followed by the one for the host system and guest architecture.
 QEMU arguments given after `--` override the config files, for example
@@ -122,9 +122,9 @@ On the first boot, cloud-init updates package metadata and installs Fedora's
 GNOME package group through its native package module, then reboots the guest.
 Keep the VM running until this initial installation and reboot have completed.
 
-Like the Debian VM, the Fedora VM hardware (8G memory, 8 CPUs, drives, SSH
+Like the Debian VM, the Fedora VM hardware (8G memory, 8 CPUs, drives) is
-port `2224`) is defined in `qemu/fedora44.ini`, with the accelerators, machine type and
+defined in `qemu/fedora44/config.ini`, with the accelerators, machine type and
-platform-specific devices in `qemu/fedora44-<os>-<arch>.ini`. Other Fedora settings use the `FEDORA_VM_` prefix.
+platform-specific devices in `qemu/fedora44/<os>-<arch>.ini`. Other Fedora settings use the `FEDORA_VM_` prefix.
 Run `./run-fedora44.py --help` for the complete list of overrides.
 
 ## Ubuntu 26.04
@@ -150,9 +150,9 @@ On the first boot, cloud-init installs `ubuntu-desktop-minimal` (GNOME) and
 guest. Keep the VM running until this initial installation and reboot have
 completed.
 
-The VM hardware (8G memory, 8 CPUs, drives, SSH port `2225`) is defined in
+The VM hardware (8G memory, 8 CPUs, drives) is defined in
-`qemu/ubuntu2604.ini`, with the accelerators, machine type and platform-specific
+`qemu/ubuntu2604/config.ini`, with the accelerators, machine type and platform-specific
-devices in `qemu/ubuntu2604-<os>-<arch>.ini`. Other Ubuntu
+devices in `qemu/ubuntu2604/<os>-<arch>.ini`. Other Ubuntu
 settings use the `UBUNTU_VM_` prefix. Run `./run-ubuntu2604.py --help` for the
 complete list of overrides.
 
@@ -182,10 +182,10 @@ seed ISO also carries the host's SSH public key (`$SSH_PUBLIC_KEY_FILE`, else th
 first of `~/.ssh/id_ed25519.pub`, `id_ecdsa.pub`, `id_rsa.pub`) for passwordless
 administrator login.
 The Windows VM hardware (8G memory, 8 CPUs, system disk, devices)
-is defined in `qemu/windows11.ini`, with the accelerators and machine type in
+is defined in `qemu/windows11/config.ini`, with the accelerators and machine type in
-`qemu/windows11-<os>-<arch>.ini`; the launcher renders the former to
+`qemu/windows11/<os>-<arch>.ini`; the launcher renders the former to
 `vm/windows11/qemu.ini` and loads both with `-readconfig`. Only the network
-and the installation media are still set by the launcher. QEMU arguments after
+(see Port forwards) and the installation media are still set by the launcher. QEMU arguments after
 `--` override the config files, for example `./run-windows11.py -- -m 4G -smp 4`.
 The generated answer-file ISO is stored beside the disk as
 `vm/windows11/seed.iso`.
@@ -202,3 +202,24 @@ is elsewhere:
 ```bash
 WIN11_VM_TOOLS_ISO=/custom/path/virtio-win.iso ./run-windows11.py --install-from-iso
 ```
+
+## Port forwards
+
+The host ports forwarded to the guest are not in the QEMU config files (a
+config file section cannot hold more than one `hostfwd`) but in one file per
+VM, `qemu/<vm>/forwards.conf`, which the launcher turns into the `-netdev`
+argument. Each line is `LABEL HOST_PORT GUEST_PORT`; `#` starts a comment:
+
+```
+# qemu/windows11/forwards.conf
+RDP  3389  3389
+SSH  2222  22
+```
+
+Add a line to forward another port. A rule whose host port is already in use
+is skipped with a warning. `ALMA_VM_FORWARDS`, `FEDORA_VM_FORWARDS`,
+`UBUNTU_VM_FORWARDS`, `VM_FORWARDS` (Debian) and `WIN11_VM_FORWARDS` select
+another file. `ALMA_VM_SSH_PORT`, `WIN11_VM_RDP_PORT`, `WIN11_VM_SSH_PORT`
+and `--rdp-port`/`--ssh-port` still replace the host port of the rule with the
+label `SSH` or `RDP`. The launchers import `vmforwards.py` from the repository
+root.

qemu/almalinux10/forwards.conf

@@ -0,0 +1,2 @@
+# Host ports forwarded to the guest: LABEL HOST_PORT GUEST_PORT
+SSH  2223  22

qemu/debian13/config.ini

@@ -1,6 +1,6 @@
 # QEMU configuration for the Debian 13 virtual machine, shared by all
 # architectures. The accelerators, machine type and
-# platform-specific devices are in debian13-<os>-<arch>.ini (os is linux or darwin),
+# platform-specific devices are in <os>-<arch>.ini (os is linux or darwin),
 # which QEMU reads after this file.
 #
 # run-debian13.py fills in the file path placeholders below, writes the result
@@ -50,10 +50,9 @@
   driver = "virtio-blk-pci"
   drive = "seed0"
 
-# User-mode networking with guest SSH forwarded to the host.
+# The NIC is attached to the user-mode network "net0", which the launcher
-[netdev "net0"]
+# defines with -netdev from qemu/debian13/forwards.conf because a config file
-  type = "user"
+# section cannot hold more than one hostfwd.
-  hostfwd = "tcp::2222-:22"
 
 [device "nic0"]
   driver = "virtio-net-pci"

qemu/debian13/darwin-arm64.ini

@@ -1,4 +1,4 @@
-# macOS host, arm64 part of the Debian 13 QEMU configuration; read after debian13.ini.
+# macOS host, arm64 part of the Debian 13 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: HVF on macOS, else emulation.
 [accel]

qemu/debian13/forwards.conf

@@ -0,0 +1,2 @@
+# Host ports forwarded to the guest: LABEL HOST_PORT GUEST_PORT
+SSH  2222  22

qemu/debian13/linux-amd64.ini

@@ -1,4 +1,4 @@
-# Linux host, amd64 part of the Debian 13 QEMU configuration; read after debian13.ini.
+# Linux host, amd64 part of the Debian 13 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

qemu/debian13/linux-arm64.ini

@@ -1,4 +1,4 @@
-# Linux host, arm64 part of the Debian 13 QEMU configuration; read after debian13.ini.
+# Linux host, arm64 part of the Debian 13 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

qemu/fedora44/config.ini

@@ -1,6 +1,6 @@
 # QEMU configuration for the Fedora 44 virtual machine, shared by all
 # architectures. The accelerators, machine type and
-# platform-specific devices are in fedora44-<os>-<arch>.ini (os is linux or darwin),
+# platform-specific devices are in <os>-<arch>.ini (os is linux or darwin),
 # which QEMU reads after this file.
 #
 # run-fedora44.py fills in the file path placeholders below, writes the result
@@ -50,10 +50,9 @@
   driver = "virtio-blk-pci"
   drive = "seed0"
 
-# User-mode networking with guest SSH forwarded to the host.
+# The NIC is attached to the user-mode network "net0", which the launcher
-[netdev "net0"]
+# defines with -netdev from qemu/fedora44/forwards.conf because a config file
-  type = "user"
+# section cannot hold more than one hostfwd.
-  hostfwd = "tcp::2224-:22"
 
 [device "nic0"]
   driver = "virtio-net-pci"

qemu/fedora44/darwin-arm64.ini

@@ -1,4 +1,4 @@
-# macOS host, arm64 part of the Fedora 44 QEMU configuration; read after fedora44.ini.
+# macOS host, arm64 part of the Fedora 44 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: HVF on macOS, else emulation.
 [accel]

qemu/fedora44/forwards.conf

@@ -0,0 +1,2 @@
+# Host ports forwarded to the guest: LABEL HOST_PORT GUEST_PORT
+SSH  2224  22

qemu/fedora44/linux-amd64.ini

@@ -1,4 +1,4 @@
-# Linux host, amd64 part of the Fedora 44 QEMU configuration; read after fedora44.ini.
+# Linux host, amd64 part of the Fedora 44 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

qemu/fedora44/linux-arm64.ini

@@ -1,4 +1,4 @@
-# Linux host, arm64 part of the Fedora 44 QEMU configuration; read after fedora44.ini.
+# Linux host, arm64 part of the Fedora 44 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

qemu/ubuntu2604/config.ini

@@ -1,6 +1,6 @@
 # QEMU configuration for the Ubuntu 26.04 virtual machine, shared by all
 # architectures. The accelerators, machine type and
-# platform-specific devices are in ubuntu2604-<os>-<arch>.ini (os is linux or darwin),
+# platform-specific devices are in <os>-<arch>.ini (os is linux or darwin),
 # which QEMU reads after this file.
 #
 # run-ubuntu2604.py fills in the file path placeholders below, writes the result
@@ -50,10 +50,9 @@
   driver = "virtio-blk-pci"
   drive = "seed0"
 
-# User-mode networking with guest SSH forwarded to the host.
+# The NIC is attached to the user-mode network "net0", which the launcher
-[netdev "net0"]
+# defines with -netdev from qemu/ubuntu2604/forwards.conf because a config file
-  type = "user"
+# section cannot hold more than one hostfwd.
-  hostfwd = "tcp::2225-:22"
 
 [device "nic0"]
   driver = "virtio-net-pci"

qemu/ubuntu2604/darwin-arm64.ini

@@ -1,4 +1,4 @@
-# macOS host, arm64 part of the Ubuntu 26.04 QEMU configuration; read after ubuntu2604.ini.
+# macOS host, arm64 part of the Ubuntu 26.04 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: HVF on macOS, else emulation.
 [accel]

qemu/ubuntu2604/forwards.conf

@@ -0,0 +1,2 @@
+# Host ports forwarded to the guest: LABEL HOST_PORT GUEST_PORT
+SSH  2225  22

qemu/ubuntu2604/linux-amd64.ini

@@ -1,4 +1,4 @@
-# Linux host, amd64 part of the Ubuntu 26.04 QEMU configuration; read after ubuntu2604.ini.
+# Linux host, amd64 part of the Ubuntu 26.04 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

qemu/ubuntu2604/linux-arm64.ini

@@ -1,4 +1,4 @@
-# Linux host, arm64 part of the Ubuntu 26.04 QEMU configuration; read after ubuntu2604.ini.
+# Linux host, arm64 part of the Ubuntu 26.04 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

qemu/windows11/config.ini

@@ -1,5 +1,5 @@
 # QEMU configuration for the Windows 11 virtual machine. The accelerators and machine type
-# are in windows11-<os>-<arch>.ini (os is linux or darwin), which QEMU reads after
+# are in <os>-<arch>.ini (os is linux or darwin), which QEMU reads after
 # this file.
 #
 # run-windows11.py fills in the file path placeholders below, writes the result
@@ -30,8 +30,8 @@
 
 # System disk image; the device that exposes it (and the NIC, which is
 # attached to the user-mode network "net0" that the launcher defines with
-# -netdev because a config file section cannot hold more than one hostfwd) is in
+# -netdev from qemu/windows11/forwards.conf because a config file section cannot hold
-# the architecture file.
+# more than one hostfwd) is in the architecture file.
 [drive "system_disk"]
   if = "none"
   format = "qcow2"

qemu/windows11/darwin-arm64.ini

@@ -1,4 +1,4 @@
-# macOS host, arm64 part of the Windows 11 QEMU configuration; read after windows11.ini.
+# macOS host, arm64 part of the Windows 11 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: HVF on macOS, else emulation.
 [accel]

qemu/windows11/forwards.conf

@@ -0,0 +1,5 @@
+# Host ports forwarded to the guest: LABEL HOST_PORT GUEST_PORT
+# --rdp-port and --ssh-port (or WIN11_VM_RDP_PORT and WIN11_VM_SSH_PORT)
+# replace the host port of the RDP and SSH rules.
+RDP  3389  3389
+SSH  2222  22

qemu/windows11/linux-amd64.ini

@@ -1,4 +1,4 @@
-# Linux host, amd64 part of the Windows 11 QEMU configuration; read after windows11.ini.
+# Linux host, amd64 part of the Windows 11 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

qemu/windows11/linux-arm64.ini

@@ -1,4 +1,4 @@
-# Linux host, arm64 part of the Windows 11 QEMU configuration; read after windows11.ini.
+# Linux host, arm64 part of the Windows 11 QEMU configuration; read after config.ini.
 
 # Accelerators are tried in order: KVM on Linux, else emulation.
 [accel]

run-almalinux10.py

@@ -8,6 +8,8 @@ import subprocess
 import sys
 from pathlib import Path
 
+import vmforwards
+
 script_dir = Path(__file__).resolve().parent
 env = os.environ.get
 
@@ -55,7 +57,9 @@ state_dir = Path(env("ALMA_VM_STATE_DIR") or script_dir / "vm" / "almalinux10")
 disk_size = env("ALMA_VM_DISK_SIZE") or "20G"
 memory = env("ALMA_VM_MEMORY") or "8G"
 cpus = env("ALMA_VM_CPUS") or "8"
-ssh_port = env("ALMA_VM_SSH_PORT") or "2223"
+ssh_port = env("ALMA_VM_SSH_PORT")
+forwards_file = Path(
+    env("ALMA_VM_FORWARDS") or script_dir / "qemu" / "almalinux10" / "forwards.conf")
 
 
 def normalize_arch(arch):
@@ -127,6 +131,8 @@ Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--state-dir DIR] [
 Start an AlmaLinux 10 Generic Cloud virtual machine. The launcher obtains a
 missing base image through ../vm-images/download-images.sh and creates a
 writable overlay in the state directory, leaving the base image unchanged.
+Host port forwards, one "LABEL HOST_PORT GUEST_PORT" rule per line, are read
+from qemu/almalinux10/forwards.conf.
 
 Options:
   --daemon         Run in the background while keeping the graphical window
@@ -138,7 +144,9 @@ Options:
 Environment variables:
   ALMA_VM_MEMORY         Guest memory (default: 8G)
   ALMA_VM_CPUS           Virtual CPU count (default: 8)
-  ALMA_VM_SSH_PORT       Host port forwarded to guest SSH (default: 2223)
+  ALMA_VM_SSH_PORT       Host port of the SSH rule in the port forward file
+                         (default: from the file, 2223)
+  ALMA_VM_FORWARDS       Port forward file (default: qemu/almalinux10/forwards.conf)
   ALMA_VM_BASE_IMAGE     Base qcow2 image path (default: resolved by shared image helper)
   ALMA_VM_SEED_IMAGE     cloud-init seed ISO path (default: alongside the VM disk)
   ALMA_VM_STATE_DIR      Runtime state directory (default: vm/almalinux10)
@@ -240,6 +248,9 @@ if not disk_image.is_file():
 is_macos = platform.system() == "Darwin"
 display_backend = env("ALMA_VM_DISPLAY") or ("cocoa" if is_macos else "gtk")
 
+forwards = vmforwards.usable_forwards(vmforwards.load_forwards(
+    forwards_file, {"SSH": ssh_port} if ssh_port else None))
+
 qemu_args = [
     "-name", "almalinux10",
     "-machine", machine_type,
@@ -252,7 +263,8 @@ qemu_args = [
     "-device", "virtio-blk-pci,drive=disk0",
     "-drive", f"file={seed_image},if=none,id=seed0,format=raw,readonly=on",
     "-device", "virtio-blk-pci,drive=seed0",
-    "-nic", f"user,model=virtio-net-pci,hostfwd=tcp::{ssh_port}-:22",
+    "-netdev", vmforwards.netdev_argument(forwards),
+    "-device", "virtio-net-pci,netdev=net0",
 ]
 
 if machine_type == "virt":
@@ -274,8 +286,8 @@ else:
     qemu_args += ["-accel", "tcg", "-cpu", "max"]
     accelerator = "TCG"
 
-print(f"Starting AlmaLinux 10 ({host_arch}) with {accelerator} acceleration; "
+print(f"Starting AlmaLinux 10 ({host_arch}) with {accelerator} acceleration.", flush=True)
-      f"SSH is forwarded to localhost:{ssh_port}.", flush=True)
+vmforwards.print_forwards(forwards)
 
 if daemonize:
     log_file.write_text("")

run-debian13.py

@@ -3,13 +3,14 @@
 
 import os
 import platform
-import re
 import shutil
 import string
 import subprocess
 import sys
 from pathlib import Path
 
+import vmforwards
+
 script_dir = Path(__file__).resolve().parent
 env = os.environ.get
 
@@ -68,11 +69,13 @@ def normalize_arch(arch):
 native_arch = normalize_arch(platform.machine())
 host_arch = normalize_arch(env("VM_IMAGE_ARCH") or native_arch)
 qemu_binary = "qemu-system-aarch64" if host_arch == "arm64" else "qemu-system-x86_64"
-qemu_config_template = Path(env("VM_QEMU_CONFIG") or script_dir / "qemu" / "debian13.ini")
+qemu_config_template = Path(env("VM_QEMU_CONFIG") or script_dir / "qemu" / "debian13" / "config.ini")
 host_os = platform.system().lower()
 if host_os == "darwin" and host_arch == "amd64":
     die("amd64 guests are not supported on macOS hosts; use an arm64 image")
-qemu_platform_config = script_dir / "qemu" / f"debian13-{host_os}-{host_arch}.ini"
+qemu_platform_config = script_dir / "qemu" / "debian13" / f"{host_os}-{host_arch}.ini"
+forwards_file = Path(
+    env("VM_FORWARDS") or script_dir / "qemu" / "debian13" / "forwards.conf")
 
 
 def pick_firmware(override, *candidates):
@@ -125,10 +128,12 @@ Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--state-dir DIR] [
 
 Start the Debian 13 virtual machine. A writable overlay is created in the state
 directory (default: vm/debian13/), so the downloaded base image is never
-modified. The VM hardware (memory, CPUs, SSH port forward, ...) is defined in
+modified. The VM hardware (memory, CPUs, ...) is defined in
-qemu/debian13.ini, which is rendered to qemu.ini in the state directory and
+qemu/debian13/config.ini, which is rendered to qemu.ini in the state directory and
-loaded with QEMU's -readconfig, followed by qemu/debian13-<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64). Later
+loaded with QEMU's -readconfig, followed by qemu/debian13/<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64). Later
 QEMU arguments override them, e.g. `-- -m 4G -smp 4`.
+Host port forwards, one "LABEL HOST_PORT GUEST_PORT" rule per line, are
+read from qemu/debian13/forwards.conf.
 
 Options:
   --daemon         Run in the background while keeping the graphical window
@@ -148,7 +153,8 @@ Environment variables:
   VM_UEFI_VARS   UEFI variable-store template path (auto-detected for the selected architecture)
   VM_DISPLAY     QEMU display backend (default: cocoa on macOS, gtk elsewhere)
   VM_QEMU_CONFIG QEMU config template rendered into the state directory and
-                 passed to -readconfig (default: qemu/debian13.ini)
+                 passed to -readconfig (default: qemu/debian13/config.ini)
+  VM_FORWARDS    Port forward file (default: qemu/debian13/forwards.conf)
 """)
 
 
@@ -264,24 +270,24 @@ except (KeyError, ValueError) as error:
     die(f"invalid placeholder in {qemu_config_template}: {error}")
 qemu_config.write_text(qemu_config_text)
 
+forwards = vmforwards.usable_forwards(vmforwards.load_forwards(forwards_file))
+
 qemu_args = [
     "-readconfig", str(qemu_config),
     "-readconfig", str(qemu_platform_config),
     # "max" is the host CPU under KVM/HVF and the fullest model under TCG.
     "-cpu", "max",
-    # The config file's [netdev] does not stop QEMU from adding its default
+    # A config file section cannot hold two hostfwd entries, so the network
-    # NIC, a second user network without the SSH port forward.
+    # that the NIC in the config file uses is defined here. -nic none stops
+    # QEMU from adding its default NIC as well.
+    "-netdev", vmforwards.netdev_argument(forwards),
     "-nic", "none",
     "-display", display_backend,
 ]
 
 print(f"Starting {host_arch} VM from {qemu_config_template} "
       f"and {qemu_platform_config}.", flush=True)
-# The SSH port forward lives in the config file, e.g. hostfwd = "tcp::2222-:22".
+vmforwards.print_forwards(forwards)
-ssh_forward = re.search(r'hostfwd\s*=\s*"tcp:[^:"]*:(\d+)-[^:"]*:22"', qemu_config_text)
-if ssh_forward:
-    print(f"SSH is forwarded to localhost:{ssh_forward.group(1)}: "
-          f"ssh -p {ssh_forward.group(1)} guofang@localhost", flush=True)
 
 if daemonize:
     log_file.write_text("")

run-fedora44.py

@@ -3,13 +3,14 @@
 
 import os
 import platform
-import re
 import shutil
 import string
 import subprocess
 import sys
 from pathlib import Path
 
+import vmforwards
+
 script_dir = Path(__file__).resolve().parent
 env = os.environ.get
 
@@ -69,11 +70,13 @@ native_arch = normalize_arch(platform.machine())
 host_arch = normalize_arch(env("VM_IMAGE_ARCH") or native_arch)
 qemu_binary = "qemu-system-aarch64" if host_arch == "arm64" else "qemu-system-x86_64"
 qemu_config_template = Path(
-    env("FEDORA_VM_QEMU_CONFIG") or script_dir / "qemu" / "fedora44.ini")
+    env("FEDORA_VM_QEMU_CONFIG") or script_dir / "qemu" / "fedora44" / "config.ini")
 host_os = platform.system().lower()
 if host_os == "darwin" and host_arch == "amd64":
     die("amd64 guests are not supported on macOS hosts; use an arm64 image")
-qemu_platform_config = script_dir / "qemu" / f"fedora44-{host_os}-{host_arch}.ini"
+qemu_platform_config = script_dir / "qemu" / "fedora44" / f"{host_os}-{host_arch}.ini"
+forwards_file = Path(
+    env("FEDORA_VM_FORWARDS") or script_dir / "qemu" / "fedora44" / "forwards.conf")
 
 
 def pick_firmware(override, *candidates):
@@ -127,10 +130,12 @@ Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--state-dir DIR] [
 Start a Fedora 44 Cloud Base virtual machine. The launcher obtains a missing
 base image through the shared image helper and creates a writable overlay
 in the state directory, leaving the base image unchanged. The VM hardware
-(memory, CPUs, SSH port forward, ...) is defined in qemu/fedora44.ini, which is
+(memory, CPUs, ...) is defined in qemu/fedora44/config.ini, which is
 rendered to qemu.ini in the state directory and loaded with QEMU's -readconfig,
-followed by qemu/fedora44-<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64). Later QEMU arguments override them, e.g.
+followed by qemu/fedora44/<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64). Later QEMU arguments override them, e.g.
 `-- -m 4G -smp 4`.
+Host port forwards, one "LABEL HOST_PORT GUEST_PORT" rule per line, are
+read from qemu/fedora44/forwards.conf.
 
 Options:
   --daemon         Run in the background while keeping the graphical window
@@ -150,7 +155,8 @@ Environment variables:
   FEDORA_VM_UEFI_VARS      UEFI variable-store template path (auto-detected for the selected architecture)
   FEDORA_VM_DISPLAY        QEMU display backend (default: cocoa on macOS, gtk elsewhere)
   FEDORA_VM_QEMU_CONFIG    QEMU config template rendered into the state directory and
-                           passed to -readconfig (default: qemu/fedora44.ini)
+                           passed to -readconfig (default: qemu/fedora44/config.ini)
+  FEDORA_VM_FORWARDS       Port forward file (default: qemu/fedora44/forwards.conf)
 """)
 
 
@@ -266,24 +272,24 @@ except (KeyError, ValueError) as error:
     die(f"invalid placeholder in {qemu_config_template}: {error}")
 qemu_config.write_text(qemu_config_text)
 
+forwards = vmforwards.usable_forwards(vmforwards.load_forwards(forwards_file))
+
 qemu_args = [
     "-readconfig", str(qemu_config),
     "-readconfig", str(qemu_platform_config),
     # "max" is the host CPU under KVM/HVF and the fullest model under TCG.
     "-cpu", "max",
-    # The config file's [netdev] does not stop QEMU from adding its default
+    # A config file section cannot hold two hostfwd entries, so the network
-    # NIC, a second user network without the SSH port forward.
+    # that the NIC in the config file uses is defined here. -nic none stops
+    # QEMU from adding its default NIC as well.
+    "-netdev", vmforwards.netdev_argument(forwards),
     "-nic", "none",
     "-display", display_backend,
 ]
 
 print(f"Starting Fedora 44 ({host_arch}) from {qemu_config_template} "
       f"and {qemu_platform_config}.", flush=True)
-# The SSH port forward lives in the config file, e.g. hostfwd = "tcp::2224-:22".
+vmforwards.print_forwards(forwards)
-ssh_forward = re.search(r'hostfwd\s*=\s*"tcp:[^:"]*:(\d+)-[^:"]*:22"', qemu_config_text)
-if ssh_forward:
-    print(f"SSH is forwarded to localhost:{ssh_forward.group(1)}: "
-          f"ssh -p {ssh_forward.group(1)} guofang@localhost", flush=True)
 
 if daemonize:
     log_file.write_text("")

run-ubuntu2604.py

@@ -3,13 +3,14 @@
 
 import os
 import platform
-import re
 import shutil
 import string
 import subprocess
 import sys
 from pathlib import Path
 
+import vmforwards
+
 script_dir = Path(__file__).resolve().parent
 env = os.environ.get
 
@@ -69,11 +70,13 @@ native_arch = normalize_arch(platform.machine())
 host_arch = normalize_arch(env("VM_IMAGE_ARCH") or native_arch)
 qemu_binary = "qemu-system-aarch64" if host_arch == "arm64" else "qemu-system-x86_64"
 qemu_config_template = Path(
-    env("UBUNTU_VM_QEMU_CONFIG") or script_dir / "qemu" / "ubuntu2604.ini")
+    env("UBUNTU_VM_QEMU_CONFIG") or script_dir / "qemu" / "ubuntu2604" / "config.ini")
 host_os = platform.system().lower()
 if host_os == "darwin" and host_arch == "amd64":
     die("amd64 guests are not supported on macOS hosts; use an arm64 image")
-qemu_platform_config = script_dir / "qemu" / f"ubuntu2604-{host_os}-{host_arch}.ini"
+qemu_platform_config = script_dir / "qemu" / "ubuntu2604" / f"{host_os}-{host_arch}.ini"
+forwards_file = Path(
+    env("UBUNTU_VM_FORWARDS") or script_dir / "qemu" / "ubuntu2604" / "forwards.conf")
 
 
 def pick_firmware(override, *candidates):
@@ -126,11 +129,13 @@ Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--state-dir DIR] [
 
 Start an Ubuntu 26.04 LTS cloud image virtual machine. A writable overlay is
 created in the state directory (default: vm/ubuntu2604/), so the downloaded
-base image is never modified. The VM hardware (memory, CPUs, SSH port forward,
+base image is never modified. The VM hardware (memory, CPUs, ...) is defined
-...) is defined in qemu/ubuntu2604.ini, which is rendered to qemu.ini in the
+in qemu/ubuntu2604/config.ini, which is rendered to qemu.ini in the state directory
-state directory and loaded with QEMU's -readconfig, followed by
+and loaded with QEMU's -readconfig, followed by
-qemu/ubuntu2604-<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64). Later QEMU arguments override them, e.g.
+qemu/ubuntu2604/<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64). Later QEMU arguments override them, e.g.
 `-- -m 4G -smp 4`.
+Host port forwards, one "LABEL HOST_PORT GUEST_PORT" rule per line, are
+read from qemu/ubuntu2604/forwards.conf.
 
 Options:
   --daemon         Run in the background while keeping the graphical window
@@ -150,7 +155,8 @@ Environment variables:
   UBUNTU_VM_UEFI_VARS      UEFI variable-store template path (auto-detected for the selected architecture)
   UBUNTU_VM_DISPLAY        QEMU display backend (default: cocoa on macOS, gtk elsewhere)
   UBUNTU_VM_QEMU_CONFIG    QEMU config template rendered into the state directory and
-                           passed to -readconfig (default: qemu/ubuntu2604.ini)
+                           passed to -readconfig (default: qemu/ubuntu2604/config.ini)
+  UBUNTU_VM_FORWARDS       Port forward file (default: qemu/ubuntu2604/forwards.conf)
 """)
 
 
@@ -266,24 +272,24 @@ except (KeyError, ValueError) as error:
     die(f"invalid placeholder in {qemu_config_template}: {error}")
 qemu_config.write_text(qemu_config_text)
 
+forwards = vmforwards.usable_forwards(vmforwards.load_forwards(forwards_file))
+
 qemu_args = [
     "-readconfig", str(qemu_config),
     "-readconfig", str(qemu_platform_config),
     # "max" is the host CPU under KVM/HVF and the fullest model under TCG.
     "-cpu", "max",
-    # The config file's [netdev] does not stop QEMU from adding its default
+    # A config file section cannot hold two hostfwd entries, so the network
-    # NIC, a second user network without the SSH port forward.
+    # that the NIC in the config file uses is defined here. -nic none stops
+    # QEMU from adding its default NIC as well.
+    "-netdev", vmforwards.netdev_argument(forwards),
     "-nic", "none",
     "-display", display_backend,
 ]
 
 print(f"Starting Ubuntu 26.04 ({host_arch}) from {qemu_config_template} "
       f"and {qemu_platform_config}.", flush=True)
-# The SSH port forward lives in the config file, e.g. hostfwd = "tcp::2225-:22".
+vmforwards.print_forwards(forwards)
-ssh_forward = re.search(r'hostfwd\s*=\s*"tcp:[^:"]*:(\d+)-[^:"]*:22"', qemu_config_text)
-if ssh_forward:
-    print(f"SSH is forwarded to localhost:{ssh_forward.group(1)}: "
-          f"ssh -p {ssh_forward.group(1)} guofang@localhost", flush=True)
 
 if daemonize:
     log_file.write_text("")

run-windows11.py

@@ -4,12 +4,13 @@
 import os
 import platform
 import shutil
-import socket
 import string
 import subprocess
 import sys
 from pathlib import Path
 
+import vmforwards
+
 script_dir = Path(__file__).resolve().parent
 env = os.environ.get
 
@@ -34,17 +35,6 @@ def capture(command):
     return result.stdout.rstrip("\n")
 
 
-def port_in_use(port):
-    """True if a host TCP port cannot be bound, as QEMU does for a hostfwd rule."""
-    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as probe:
-        probe.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        try:
-            probe.bind(("", int(port)))
-        except OSError:
-            return True
-    return False
-
-
 def is_executable(path):
     return path.is_file() and os.access(path, os.X_OK)
 
@@ -63,10 +53,12 @@ def find_image_downloader():
 
 state_dir = Path(env("WIN11_VM_STATE_DIR") or script_dir / "vm" / "windows11")
 disk_size = env("WIN11_VM_DISK_SIZE") or "64G"
-rdp_port = env("WIN11_VM_RDP_PORT") or "3389"
+rdp_port = env("WIN11_VM_RDP_PORT")
-ssh_port = env("WIN11_VM_SSH_PORT") or "2222"
+ssh_port = env("WIN11_VM_SSH_PORT")
+forwards_file = Path(
+    env("WIN11_VM_FORWARDS") or script_dir / "qemu" / "windows11" / "forwards.conf")
 qemu_config_template = Path(
-    env("WIN11_VM_QEMU_CONFIG") or script_dir / "qemu" / "windows11.ini")
+    env("WIN11_VM_QEMU_CONFIG") or script_dir / "qemu" / "windows11" / "config.ini")
 
 
 def normalize_arch(arch):
@@ -95,8 +87,8 @@ Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--seed-only] [--vn
 If the system disk (DIR/disk.qcow2, see --state-dir) is missing, create it from
 the Windows 11 QCOW2 base image.
 The VM hardware (accelerator, memory, CPUs, drives, devices) is defined in
-qemu/windows11.ini, which is rendered to qemu.ini in the state directory and
+qemu/windows11/config.ini, which is rendered to qemu.ini in the state directory and
-loaded with QEMU's -readconfig, followed by qemu/windows11-<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64, chosen from the host system and
+loaded with QEMU's -readconfig, followed by qemu/windows11/<os>-<arch>.ini (os is linux or darwin, arch is amd64 or arm64, chosen from the host system and
 architecture, --arch or VM_IMAGE_ARCH). Later QEMU arguments override them, e.g. -- -m 4G -smp 4.
 Use --install-from-iso to perform an automatic ISO installation instead, or
 --install-from-img to install from a disk image built from the ISO.
@@ -124,10 +116,10 @@ Options:
                       host runs under slow TCG emulation
   --state-dir DIR     Directory for the VM disk, seed ISO and runtime files
                       (default: vm/windows11; overrides WIN11_VM_STATE_DIR)
-  --rdp-port PORT     Host port forwarded to guest RDP (default: 3389;
+  --rdp-port PORT     Host port of the RDP rule in the port forward file
-                      overrides WIN11_VM_RDP_PORT)
+                      (default: 3389; overrides WIN11_VM_RDP_PORT)
-  --ssh-port PORT     Host port forwarded to guest SSH (default: 2222;
+  --ssh-port PORT     Host port of the SSH rule in the port forward file
-                      overrides WIN11_VM_SSH_PORT)
+                      (default: 2222; overrides WIN11_VM_SSH_PORT)
   -h, --help          Show this help
 
 Environment variables:
@@ -135,8 +127,9 @@ Environment variables:
   WIN11_VM_INSTALL_ISO  Windows 11 installation ISO used with --install-from-iso
                         (--install-from-img uses the same path ending in .img)
   WIN11_VM_TOOLS_ISO    VirtIO Windows tools ISO (default: resolved by shared image helper)
-  WIN11_VM_RDP_PORT     Host RDP port (default: 3389)
+  WIN11_VM_RDP_PORT     Host RDP port (default: from the port forward file, 3389)
-  WIN11_VM_SSH_PORT     Host SSH port (default: 2222)
+  WIN11_VM_SSH_PORT     Host SSH port (default: from the port forward file, 2222)
+  WIN11_VM_FORWARDS     Port forward file (default: qemu/windows11/forwards.conf)
   WIN11_VM_STATE_DIR    Runtime directory (default: vm/windows11)
   WIN11_VM_DISK_IMAGE   System disk path
   WIN11_VM_DISK_SIZE    New system disk size (default: 64G)
@@ -144,7 +137,7 @@ Environment variables:
   WIN11_VM_UEFI_CODE    OVMF read-only firmware path (auto-detected if unset)
   WIN11_VM_UEFI_VARS    OVMF variable-store template path (auto-detected if unset)
   WIN11_VM_QEMU_CONFIG  QEMU config template passed to -readconfig
-                        (default: qemu/windows11.ini)
+                        (default: qemu/windows11/config.ini)
   WIN11_VM_DISPLAY      QEMU display backend (default: cocoa on macOS,
                         gtk elsewhere)
 """)
@@ -209,7 +202,7 @@ qemu_binary = "qemu-system-aarch64" if host_arch == "arm64" else "qemu-system-x8
 host_os = platform.system().lower()
 if host_os == "darwin" and host_arch == "amd64":
     die("amd64 guests are not supported on macOS hosts; use an arm64 image")
-qemu_platform_config = script_dir / "qemu" / f"windows11-{host_os}-{host_arch}.ini"
+qemu_platform_config = script_dir / "qemu" / "windows11" / f"{host_os}-{host_arch}.ini"
 
 
 def pick_firmware(override, *candidates):
@@ -430,18 +423,9 @@ except (KeyError, ValueError) as error:
     die(f"invalid placeholder in {qemu_config_template}: {error}")
 qemu_config.write_text(qemu_config_text)
 
-# QEMU refuses to start when a forwarded host port is taken, so warn and leave
+# Each rule of the port forward file is one hostfwd entry of the network.
-# that forward out instead.
+forwards = vmforwards.usable_forwards(vmforwards.load_forwards(
-forwards = []
+    forwards_file, {label: port for label, port in (("RDP", rdp_port), ("SSH", ssh_port)) if port}))
-forwarded_ports = []
-for label, host_port, guest_port in (("RDP", rdp_port, 3389), ("SSH", ssh_port, 22)):
-    in_use = port_in_use(host_port)
-    forwarded_ports.append((label, host_port, not in_use))
-    if in_use:
-        print(f"Warning: host port {host_port} is already in use; "
-              f"{label} will not be forwarded to the guest.", file=sys.stderr)
-    else:
-        forwards.append(f"hostfwd=tcp::{host_port}-:{guest_port}")
 
 # Neither Windows Setup nor the base image has the viogpudo driver yet, and
 # without it the virtio-gpu in the config file shows "display output is not
@@ -456,7 +440,7 @@ qemu_args += [
     # A config file section cannot hold two hostfwd entries, so the network
     # that the NIC in the config file uses is defined here. -nic none stops
     # QEMU from adding its default NIC as well.
-    "-netdev", ",".join(["user,id=net0", *forwards]),
+    "-netdev", vmforwards.netdev_argument(forwards),
     "-nic", "none",
     "-display", display_backend,
     # "-display", "none", "-spice", "port=5900,addr=127.0.0.1,disable-ticketing=on,agent-mouse=off", "-device", "virtio-vga",
@@ -499,7 +483,7 @@ elif installing:
 else:
     print("Starting Windows 11 normally.")
 print("Account: guofang / password; " + "; ".join(
-    f"{label}: 0.0.0.0:{port}" for label, port, forwarded in forwarded_ports if forwarded),
+    f"{forward.label}: 0.0.0.0:{forward.host_port}" for forward in forwards),
     flush=True)
 
 if daemonize:

vmforwards.py

@@ -0,0 +1,96 @@
+"""Host port forwards for the QEMU user-mode network, read from a .forwards file.
+
+Each line of the file is "LABEL HOST_PORT GUEST_PORT"; "#" starts a comment.
+A QEMU config file section cannot hold more than one hostfwd entry, so the
+launchers build the -netdev argument from these rules instead.
+"""
+
+import socket
+import sys
+from collections import namedtuple
+
+Forward = namedtuple("Forward", "label host_port guest_port")
+
+
+def _die(message):
+    print(f"Error: {message}", file=sys.stderr)
+    sys.exit(1)
+
+
+def _port(text, where):
+    if not (text.isascii() and text.isdigit() and 1 <= int(text) <= 65535):
+        _die(f"{where}: not a port number from 1 to 65535: {text}")
+    return int(text)
+
+
+def port_in_use(port):
+    """True if a host TCP port cannot be bound, as QEMU does for a hostfwd rule."""
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as probe:
+        probe.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        try:
+            probe.bind(("", int(port)))
+        except OSError:
+            return True
+    return False
+
+
+def load_forwards(path, host_port_overrides=None):
+    """Read the rules in a .forwards file.
+
+    host_port_overrides maps a label to a host port that replaces the one in
+    the file, e.g. {"SSH": "2200"}.
+    """
+    if not path.is_file():
+        _die(f"port forward file was not found: {path}")
+    forwards = []
+    for number, line in enumerate(path.read_text().splitlines(), 1):
+        fields = line.partition("#")[0].split()
+        if not fields:
+            continue
+        where = f"{path}:{number}"
+        if len(fields) != 3:
+            _die(f"{where}: expected LABEL HOST_PORT GUEST_PORT: {line.strip()}")
+        label, host_port, guest_port = fields
+        if any(forward.label == label for forward in forwards):
+            _die(f"{where}: duplicate label: {label}")
+        forwards.append(Forward(label, _port(host_port, where), _port(guest_port, where)))
+    for label, host_port in (host_port_overrides or {}).items():
+        if not any(forward.label == label for forward in forwards):
+            _die(f"{path} has no {label} rule to override the port of")
+        forwards = [forward._replace(host_port=_port(str(host_port), f"{label} port"))
+                    if forward.label == label else forward for forward in forwards]
+    seen = set()
+    for forward in forwards:
+        if forward.host_port in seen:
+            _die(f"{path}: host port {forward.host_port} is used by more than one rule")
+        seen.add(forward.host_port)
+    return forwards
+
+
+def usable_forwards(forwards):
+    """Drop (with a warning) the rules whose host port is taken.
+
+    QEMU refuses to start when a forwarded host port is taken.
+    """
+    usable = []
+    for forward in forwards:
+        if port_in_use(forward.host_port):
+            print(f"Warning: host port {forward.host_port} is already in use; "
+                  f"{forward.label} will not be forwarded to the guest.", file=sys.stderr)
+        else:
+            usable.append(forward)
+    return usable
+
+
+def netdev_argument(forwards, netdev_id="net0"):
+    """The value of -netdev for a user-mode network with the given rules."""
+    return ",".join([f"user,id={netdev_id}", *(
+        f"hostfwd=tcp::{forward.host_port}-:{forward.guest_port}" for forward in forwards)])
+
+
+def print_forwards(forwards):
+    for forward in forwards:
+        print(f"{forward.label}: localhost:{forward.host_port} -> guest port "
+              f"{forward.guest_port}", flush=True)
+        if forward.guest_port == 22:
+            print(f"  ssh -p {forward.host_port} guofang@localhost", flush=True)

windows11-arm64-install-speed.md

@@ -20,7 +20,7 @@
 |---|---|
 | 主机 | Apple M5 Max，arm64，macOS 26.4，18 核，48 GB 内存 |
 | QEMU | 11.1.2，`qemu-system-aarch64`，加速器 HVF |
-| 客户机配置 | `qemu/windows11.ini` + `qemu/windows11-darwin-arm64.ini`（`virt` 机型，8 vCPU，8G 内存，NVMe 系统盘，virtio-net，ramfb，usb-kbd/usb-tablet） |
+| 客户机配置 | `qemu/windows11/config.ini` + `qemu/windows11/darwin-arm64.ini`（`virt` 机型，8 vCPU，8G 内存，NVMe 系统盘，virtio-net，ramfb，usb-kbd/usb-tablet） |
 | 安装 ISO | `Windows11_Client_arm64_en-us_26300_9457.iso`（卷标 `CCCOMA_A64FRE_EN-US_DV9`，`install.wim` 7.6 GB，`boot.wim` 630 MB） |
 | 驱动 ISO | `virtio-win.iso`（含 ARM64 驱动目录，根目录只有 x64/x86 的 MSI） |
 
@@ -200,7 +200,7 @@ UTM 5.0.8 带有这个修复；Homebrew 的 QEMU 11.1.2 没有，所以上游版
 
 ### 处理
 
-在 `qemu/windows11-darwin-arm64.ini` 的 `[machine]` 加 `kernel-irqchip = "off"`，改用模拟的中断控制器。
+在 `qemu/windows11/darwin-arm64.ini` 的 `[machine]` 加 `kernel-irqchip = "off"`，改用模拟的中断控制器。
 这一项改完后速度明显提升，已确认和 UTM 一致。
 
 ```ini