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Defer configuration by default and manage vpn-router.conf with ucf

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Add platform = none as the shipped default so installing the package
changes nothing on the machine until a platform is chosen. Add a mode
setting (manual/interfaces/auto) controlling how much of the network
configuration is supplied versus detected from the system. Manage
/etc/vpn-router/vpn-router.conf with ucf instead of writing it once,
so dpkg-reconfigure can safely reapply debconf answers without
clobbering local edits. Extend NAT/forward rules to all local subnets,
not just the first.
This commit is contained in:
slawek
2026-08-23 17:15:49 +02:00
parent 083ad9a596
commit 7cb2f1b8dd
14 changed files with 439 additions and 124 deletions
Download Patch File Download Diff File Expand all files Collapse all files
debian-package/debian/config
+35 -3
View File
@@ -2,13 +2,45 @@
set -e
. /usr/share/debconf/confmodule
# Every question has a default, so a non-interactive install with nothing
# preseeded completes without prompting. The defaults are platform "none" and
# mode "manual", which together mean: install the files, configure nothing.
db_input high vpn-router/platform || true
db_input high vpn-router/external_interface || true
db_input high vpn-router/internal_interface || true
db_go || true
db_get vpn-router/platform
if [ "$RET" = "none" ]; then
# Configuration is deferred. Asking anything else would collect answers
# that nothing is going to apply.
exit 0
fi
db_input high vpn-router/mode || true
db_go || true
# The mode says how much the operator supplies, so it decides which interface
# and address questions are worth asking.
db_get vpn-router/mode
case "$RET" in
manual)
db_input high vpn-router/external_interface || true
db_input high vpn-router/internal_interface || true
db_input high vpn-router/int_addr || true
db_input high vpn-router/int_gateway_ip || true
;;
interfaces)
db_input high vpn-router/external_interface || true
db_input high vpn-router/internal_interface || true
;;
auto)
;;
esac
db_go || true
db_input high vpn-router/local_fqdn || true
db_input high vpn-router/local_id_mode || true
db_input high vpn-router/local_cidrs || true
db_input high vpn-router/int_gateway_ip || true
db_input high vpn-router/remote_addrs || true
db_input high vpn-router/remote_id || true
db_input high vpn-router/remote_cidrs || true
debian-package/debian/control
+1
View File
@@ -16,6 +16,7 @@ Depends: ${misc:Depends},
wireguard-tools,
ufw,
debconf,
ucf,
openssl,
python3,
python3-jinja2,
debian-package/debian/install
+1 -1
View File
@@ -3,7 +3,7 @@ src/usr/lib/vpn-router/vpnrouter.py usr/lib/vpn-router/
src/usr/lib/vpn-router/simple-ca usr/lib/vpn-router/
src/usr/lib/vpn-router/configure usr/lib/vpn-router/
src/usr/lib/vpn-router/setup usr/lib/vpn-router/
src/usr/lib/vpn-router/seed-config usr/lib/vpn-router/
src/usr/lib/vpn-router/generate-config usr/lib/vpn-router/
src/usr/lib/vpn-router/vpnrouter_platforms/*.py usr/lib/vpn-router/vpnrouter_platforms/
src/usr/share/vpn-router/templates/* usr/share/vpn-router/templates/
src/usr/share/doc/vpn-router/vpn-router.conf.example usr/share/doc/vpn-router/
debian-package/debian/postinst
+17 -4
View File
@@ -6,6 +6,8 @@ case "$1" in
configure)
# --- Read the installer's answers ---
db_get vpn-router/platform; VPN_ROUTER_PLATFORM="$RET"
db_get vpn-router/mode; VPN_ROUTER_MODE="$RET"
db_get vpn-router/int_addr; VPN_ROUTER_INT_ADDR="$RET"
db_get vpn-router/external_interface; VPN_ROUTER_EXTERNAL_INTERFACE="$RET"
db_get vpn-router/internal_interface; VPN_ROUTER_INTERNAL_INTERFACE="$RET"
db_get vpn-router/local_fqdn; VPN_ROUTER_LOCAL_FQDN="$RET"
@@ -23,7 +25,8 @@ case "$1" in
db_get vpn-router/wg_address; VPN_ROUTER_WG_ADDRESS="$RET"
db_get vpn-router/wg_listen_port; VPN_ROUTER_WG_LISTEN_PORT="$RET"
export VPN_ROUTER_PLATFORM VPN_ROUTER_EXTERNAL_INTERFACE \
export VPN_ROUTER_PLATFORM VPN_ROUTER_MODE VPN_ROUTER_INT_ADDR \
VPN_ROUTER_EXTERNAL_INTERFACE \
VPN_ROUTER_INTERNAL_INTERFACE VPN_ROUTER_LOCAL_FQDN \
VPN_ROUTER_LOCAL_ID_MODE VPN_ROUTER_LOCAL_CIDRS \
VPN_ROUTER_INT_GATEWAY_IP \
@@ -33,10 +36,20 @@ case "$1" in
VPN_ROUTER_P2S_CA_NAME VPN_ROUTER_WG_ENABLED \
VPN_ROUTER_WG_ADDRESS VPN_ROUTER_WG_LISTEN_PORT
# --- Create the configuration file, only if it does not exist ---
/usr/lib/vpn-router/seed-config
# --- Hand a candidate configuration to ucf ---
# ucf compares it against the file in /etc and decides what to do about
# local changes, prompting through debconf only for a real conflict.
# This is what makes dpkg-reconfigure apply without destroying edits.
CANDIDATE="$(mktemp)"
/usr/lib/vpn-router/generate-config "$CANDIDATE"
ucf --three-way --debconf-ok "$CANDIDATE" /etc/vpn-router/vpn-router.conf
ucfr vpn-router /etc/vpn-router/vpn-router.conf
chmod 0600 /etc/vpn-router/vpn-router.conf
rm -f "$CANDIDATE"
# The key now lives in the configuration file; do not keep a copy.
# The key now lives in the configuration file; do not keep a copy. An
# empty answer means "leave alone" next time, so clearing it here does
# not blank the key on the next dpkg-reconfigure.
db_set vpn-router/psk ""
# Apply the sysctl drop-in shipped by this package so it takes effect
debian-package/debian/postrm
+9
View File
@@ -34,6 +34,15 @@ case "$1" in
purge)
strip_ufw_blocks
# Let ucf forget the file before it is removed, or a reinstall finds a
# stale hash and declines to lay the file down again.
if command -v ucf >/dev/null 2>&1; then
ucf --purge /etc/vpn-router/vpn-router.conf
fi
if command -v ucfr >/dev/null 2>&1; then
ucfr --purge vpn-router /etc/vpn-router/vpn-router.conf
fi
rm -f /etc/swanctl/conf.d/remote-site.conf \
/etc/swanctl/conf.d/road-warrior.conf \
/etc/systemd/resolved.conf.d/p2s-forwarder.conf \
debian-package/debian/prerm
+10 -2
View File
@@ -9,8 +9,16 @@ case "$1" in
if [ -d /run/systemd/system ]; then
swanctl --terminate --ike remote-site >/dev/null 2>&1 || true
swanctl --terminate --ike road-warrior >/dev/null 2>&1 || true
# This package enabled wg-quick@wg0, so it takes it down again.
systemctl disable --now wg-quick@wg0 >/dev/null 2>&1 || true
fi
# This package enabled wg-quick@wg0, so it takes it down again. Use the
# debhelper wrappers rather than systemctl, so the script behaves on a
# machine without systemd.
if command -v deb-systemd-invoke >/dev/null 2>&1; then
deb-systemd-invoke stop wg-quick@wg0.service >/dev/null 2>&1 || true
fi
if command -v deb-systemd-helper >/dev/null 2>&1; then
deb-systemd-helper disable wg-quick@wg0.service >/dev/null 2>&1 || true
fi
;;
esac
debian-package/debian/templates
+53 -24
View File
@@ -1,34 +1,62 @@
Template: vpn-router/platform
Type: select
Choices: generic, azure, gcp
Default: generic
Description: Platform module
Platform-specific additions to load. The router works without any of them;
a module only adds what makes sense on its platform, such as the platform
DNS resolver for road-warrior clients.
Choices: none, generic, azure, gcp
Default: none
Description: Platform:
Which platform this router runs on. The choice loads platform-specific
additions, such as the provider DNS resolver for road-warrior clients.
.
none defers configuration entirely: the package installs its files and
changes nothing on the machine. Choose it when the router will be configured
later by hand or by a configuration-management tool, then set the platform in
/etc/vpn-router/vpn-router.conf when you are ready.
.
generic configures the router with no platform-specific additions.
Template: vpn-router/mode
Type: select
Choices: manual, interfaces, auto
Default: manual
Description: Network configuration source:
How much of the network configuration you are supplying, and therefore how
much the package works out for itself:
.
manual - you give the interface names, the internal address and the internal
gateway. Nothing is detected.
.
interfaces - you give the two interface names. The internal address and
gateway are read from them.
.
auto - you give nothing. The interfaces are identified from the routing
table and their addresses read from the system. Convenient, but it can pick
the wrong interface and configure the machine incorrectly.
Template: vpn-router/external_interface
Type: string
Default:
Description: External network interface
Description: External network interface:
Name of the interface facing the untrusted network, for example eth0 or
ens4. The addresses strongSwan binds on are read from it, so they are never
configured separately.
.
Leave empty to configure the router later by editing
/etc/vpn-router/vpn-router.conf.
Template: vpn-router/internal_interface
Type: string
Default:
Description: Internal network interface
Description: Internal network interface:
Name of the interface facing the protected network, for example eth1 or
ens5. Routes for the local subnets are applied to it.
Template: vpn-router/int_addr
Type: string
Default:
Description: Internal interface address:
This host's own address on the internal network. Asked only in manual mode;
in the other modes it is read from the internal interface.
Template: vpn-router/local_fqdn
Type: string
Default:
Description: Local router FQDN
Description: Local router FQDN:
Fully-qualified domain name of this router (for example
router.example.com). Used as the road-warrior server identity and
certificate common name.
@@ -37,7 +65,7 @@ Template: vpn-router/local_id_mode
Type: select
Choices: fqdn, public_ip, internal_ip
Default: fqdn
Description: IKE local identity mode
Description: IKE local identity mode:
How to derive the IKE identity advertised to the remote site:
.
fqdn - use the FQDN, which must match what the peer expects.
@@ -49,40 +77,41 @@ Description: IKE local identity mode
Template: vpn-router/local_cidrs
Type: string
Default:
Description: Local subnet CIDR(s)
Description: Local subnet CIDR(s):
Comma-separated list of local subnet CIDRs to advertise into the
site-to-site tunnel (for example 10.0.0.0/24 or 10.0.0.0/24,10.0.1.0/24).
Template: vpn-router/int_gateway_ip
Type: string
Default:
Description: Internal network gateway IP
Description: Internal network gateway address:
Address of the next-hop gateway on the internal side, used to route the
local subnets listed above.
local subnets listed above. Asked only in manual mode; in the other modes it
is derived from the internal interface.
Template: vpn-router/remote_addrs
Type: string
Default:
Description: Remote site WAN IP address(es)
Description: Remote site WAN IP address(es):
Comma-separated list of remote gateway addresses or FQDNs for the
site-to-site IPSec tunnel.
Template: vpn-router/remote_id
Type: string
Default:
Description: Remote site IKE identity
Description: Remote site IKE identity:
IKE identity of the remote peer, without a leading @.
Template: vpn-router/remote_cidrs
Type: string
Default:
Description: Remote subnet CIDR(s)
Description: Remote subnet CIDR(s):
Comma-separated list of remote subnet CIDRs reachable through the
site-to-site tunnel (for example 192.168.0.0/24).
Template: vpn-router/psk
Type: password
Description: Pre-shared key (PSK)
Description: Pre-shared key (PSK):
Pre-shared key for the site-to-site IKEv2 tunnel. Must match the value
configured on the remote peer. Stored base64-encoded in the configuration
file and cleared from the debconf database after installation.
@@ -98,13 +127,13 @@ Description: Enable road-warrior (P2S) access?
Template: vpn-router/p2s_address_pool
Type: string
Default:
Description: Road-warrior address pool
Description: Road-warrior address pool:
CIDR block assigned to road-warrior clients (for example 172.16.0.0/24).
Template: vpn-router/p2s_ca_name
Type: string
Default: VPN Router CA
Description: Road-warrior CA name
Description: Road-warrior CA name:
Common name for the certificate authority created in /etc/vpn-router/pki
when that directory is empty. Ignored when certificates are supplied.
@@ -119,12 +148,12 @@ Description: Enable WireGuard?
Template: vpn-router/wg_address
Type: string
Default:
Description: WireGuard interface address
Description: WireGuard interface address:
Address and prefix length for the wg0 interface (for example
192.168.200.1/24).
Template: vpn-router/wg_listen_port
Type: string
Default: 51820
Description: WireGuard listen port
Description: WireGuard listen port:
UDP port that WireGuard listens on.
debian-package/src/usr/lib/vpn-router/configure
Vendored
+5 -2
View File
@@ -1,8 +1,11 @@
#!/usr/bin/python3
"""Render configuration files and provision PKI from vpn-router.conf.
Run directly to regenerate the configuration files without touching the
running system. 'setup' calls the same code before applying the rest.
Run directly to regenerate them without starting, stopping or reloading
anything. This still writes to /etc/swanctl, /etc/systemd/resolved.conf.d and
/etc/wireguard, and may create the certificate authority and add it to the host
trust store; what it leaves alone is routes, firewall rules and services.
'setup' calls the same code before applying those.
"""
import os
debian-package/src/usr/lib/vpn-router/seed-config → debian-package/src/usr/lib/vpn-router/generate-config
+34 -18
View File
@@ -1,9 +1,23 @@
#!/usr/bin/python3
"""Create /etc/vpn-router/vpn-router.conf from the installer's answers.
"""Write a candidate vpn-router.conf to the path given on the command line.
Runs once, from postinst, and only when the file does not exist. The
configuration file belongs to the operator from that point on and is never
rewritten by the package.
Called from postinst, which hands the result to ucf(1). ucf compares it with
/etc/vpn-router/vpn-router.conf and decides what to do about local changes, so
this script never writes to /etc and never has to worry about destroying an
administrator's edits.
The candidate is built in three layers, each overriding the one before:
1. the shipped defaults
2. the current contents of /etc/vpn-router/vpn-router.conf, if it exists
3. any debconf answer that was actually given
Layer 2 is what makes reconfiguration safe: a setting the administrator edited
by hand, and that debconf has nothing to say about, is carried through
unchanged, so ucf only sees a diff where something really changed. An empty
answer means "leave alone", which is why clearing the pre-shared key from the
debconf database after installation does not blank it on the next
dpkg-reconfigure.
Answers arrive as VPN_ROUTER_* environment variables. The pre-shared key is
stored base64-encoded so that arbitrary characters cannot collide with INI
@@ -21,6 +35,8 @@ import vpnrouter
# environment variable -> (section, option)
ANSWERS = {
'VPN_ROUTER_PLATFORM': ('general', 'platform'),
'VPN_ROUTER_MODE': ('general', 'mode'),
'VPN_ROUTER_INT_ADDR': ('local', 'int_addr'),
'VPN_ROUTER_EXTERNAL_INTERFACE': ('interfaces', 'external'),
'VPN_ROUTER_INTERNAL_INTERFACE': ('interfaces', 'internal'),
'VPN_ROUTER_LOCAL_FQDN': ('wan', 'local_fqdn'),
@@ -40,31 +56,31 @@ ANSWERS = {
def main():
path = vpnrouter.CONFIG_FILE
if path.exists():
return 0
if len(sys.argv) != 2:
print('usage: generate-config OUTPUT', file=sys.stderr)
return 2
output = sys.argv[1]
parser = vpnrouter.default_parser()
current = vpnrouter.load_config()
for section in parser.sections():
for option in parser[section]:
if current.has_option(section, option):
parser[section][option] = current.get(section, option)
for variable, (section, option) in ANSWERS.items():
value = os.environ.get(variable)
if value is not None and value != '':
parser[section][option] = value
if os.environ.get(variable):
parser[section][option] = os.environ[variable]
psk = os.environ.get('VPN_ROUTER_PSK', '')
if psk:
parser['remote']['psk_b64'] = base64.b64encode(
psk.encode('utf-8')).decode('ascii')
path.parent.mkdir(parents=True, exist_ok=True)
with open(path, 'w', encoding='utf-8') as handle:
with open(output, 'w', encoding='utf-8') as handle:
parser.write(handle)
os.chmod(path, 0o600)
os.chown(path, 0, 0)
print(f'vpn-router: wrote {path}')
print('vpn-router: edit it and run "systemctl restart vpn-router-setup" '
'to apply changes')
os.chmod(output, 0o600)
return 0
debian-package/src/usr/lib/vpn-router/setup
+23 -16
View File
@@ -150,14 +150,13 @@ def filter_block(ctx):
lines += ['# P2S DNS RULES END']
if vpnrouter.routing_ready(ctx):
subnet = ctx['local_subnet']
lines += [
'',
'# ROUTER FORWARD RULES START',
f'-A ufw-before-forward -s {subnet} -o {ctx["wan_iface"]} -j ACCEPT',
f'-A ufw-before-forward -d {subnet} -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT',
'# ROUTER FORWARD RULES END',
]
lines += ['', '# ROUTER FORWARD RULES START']
for subnet in ctx['local_cidr_list']:
lines += [
f'-A ufw-before-forward -s {subnet} -o {ctx["wan_iface"]} -j ACCEPT',
f'-A ufw-before-forward -d {subnet} -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT',
]
lines += ['# ROUTER FORWARD RULES END']
return ''.join(line + '\n' for line in lines)
@@ -166,7 +165,8 @@ def nat_and_mangle_block(ctx):
lines = []
if vpnrouter.routing_ready(ctx):
subnet = ctx['local_subnet']
subnets = ctx['local_cidr_list']
remote = [c.strip() for c in ctx['remote_cidrs'].split(',') if c.strip()]
lines += [
'',
'# ROUTER NAT RULES START',
@@ -174,13 +174,15 @@ def nat_and_mangle_block(ctx):
':POSTROUTING ACCEPT [0:0]',
'-F POSTROUTING',
]
for cidr in [c.strip() for c in ctx['remote_cidrs'].split(',') if c.strip()]:
lines.append(f'-A POSTROUTING -s {subnet} -d {cidr} -j RETURN')
lines += [
f'-A POSTROUTING -s {subnet} -o {ctx["wan_iface"]} -j MASQUERADE',
'COMMIT',
'# ROUTER NAT RULES END',
]
# Every RETURN precedes every MASQUERADE, so tunnel-bound traffic
# escapes NAT whichever local subnet it came from.
for subnet in subnets:
for cidr in remote:
lines.append(f'-A POSTROUTING -s {subnet} -d {cidr} -j RETURN')
for subnet in subnets:
lines.append(
f'-A POSTROUTING -s {subnet} -o {ctx["wan_iface"]} -j MASQUERADE')
lines += ['COMMIT', '# ROUTER NAT RULES END']
lines += [
'',
@@ -301,6 +303,11 @@ def main():
cfg = vpnrouter.load_config()
ctx, changed = vpnrouter.configure(cfg)
if ctx is None:
print('vpn-router: platform is none, configuration deferred; '
'set general.platform in /etc/vpn-router/vpn-router.conf')
return 0
if vpnrouter.routing_ready(ctx):
apply_routes(ctx)
debian-package/src/usr/lib/vpn-router/vpnrouter.py
+162 -24
View File
@@ -41,10 +41,10 @@ TRUST_ANCHOR = pathlib.Path('/usr/local/share/ca-certificates/vpn-router-ca.cr
# section -> option -> default
SCHEMA = {
'general': {'platform': 'generic'},
'general': {'platform': 'none', 'mode': 'manual'},
'interfaces': {'external': '', 'internal': ''},
'wan': {'local_fqdn': '', 'local_id_mode': 'fqdn'},
'local': {'cidrs': '', 'int_gateway_ip': ''},
'local': {'cidrs': '', 'int_addr': '', 'int_gateway_ip': ''},
'remote': {'addrs': '', 'id': '', 'cidrs': '', 'psk_b64': '', 'psk_file': ''},
'p2s': {'enabled': 'false', 'address_pool': '', 'ca_name': 'VPN Router CA'},
'wireguard': {'enabled': 'false', 'address': '', 'listen_port': '51820'},
@@ -52,6 +52,17 @@ SCHEMA = {
ID_MODES = ('fqdn', 'public_ip', 'internal_ip')
#: How much the operator supplies, and therefore how much may be detected.
#: manual - names and addresses given; nothing is detected
#: interfaces - names given; addresses and gateway derived from them
#: auto - nothing given; the interfaces are worked out too, accepting
#: that the result may be wrong
MODES = ('manual', 'interfaces', 'auto')
#: platform = none means configuration is deferred: files are installed and
#: nothing else happens until the operator says otherwise.
PLATFORM_NONE = 'none'
class ConfigError(Exception):
"""A setting is present but malformed."""
@@ -92,8 +103,13 @@ def default_parser():
return parser
def load_config(path=CONFIG_FILE):
"""Read the configuration, filling in defaults for anything absent."""
def load_config(path=None):
"""Read the configuration, filling in defaults for anything absent.
The path is resolved when called, not when this function is defined, so
CONFIG_FILE stays overridable.
"""
path = pathlib.Path(path) if path else CONFIG_FILE
parser = default_parser()
if path.exists():
try:
@@ -137,14 +153,35 @@ def _check_address(value, name):
def validate(cfg):
"""Reject values that are present but malformed. Absent is not an error."""
"""Reject values that are present but malformed. Absent is not an error.
The exception is general.mode, which states what the operator promised to
supply, so the values that mode requires are checked for presence too.
"""
platform = _get(cfg, 'general', 'platform')
installed = vpnrouter_platforms.available()
installed = [PLATFORM_NONE] + vpnrouter_platforms.available()
if platform and platform not in installed:
raise ConfigError(
f'general.platform: {platform!r} is not installed, expected one of '
f'{", ".join(installed)}')
mode = _get(cfg, 'general', 'mode')
if mode and mode not in MODES:
raise ConfigError(
f'general.mode: {mode!r} is not one of {", ".join(MODES)}')
if not deferred(cfg):
required = {
'manual': (('interfaces', 'external'), ('interfaces', 'internal'),
('local', 'int_addr'), ('local', 'int_gateway_ip')),
'interfaces': (('interfaces', 'external'), ('interfaces', 'internal')),
'auto': (),
}[mode or 'manual']
for section, option in required:
if not _get(cfg, section, option):
raise ConfigError(
f'{section}.{option} is required in mode {mode or "manual"}')
id_mode = _get(cfg, 'wan', 'local_id_mode')
if id_mode and id_mode not in ID_MODES:
raise ConfigError(
@@ -153,13 +190,16 @@ def validate(cfg):
_check_networks(_get(cfg, 'local', 'cidrs'), 'local.cidrs')
_check_networks(_get(cfg, 'remote', 'cidrs'), 'remote.cidrs')
_check_networks(_get(cfg, 'p2s', 'address_pool'), 'p2s.address_pool')
_check_address(_get(cfg, 'local', 'int_addr'), 'local.int_addr')
_check_address(_get(cfg, 'local', 'int_gateway_ip'), 'local.int_gateway_ip')
for option in ('external', 'internal'):
name = _get(cfg, 'interfaces', option)
if name and not (pathlib.Path('/sys/class/net') / name).exists():
raise ConfigError(
f'interfaces.{option}: interface {name!r} does not exist')
# In auto mode the names are worked out later, so there is nothing to check.
if mode != 'auto':
for option in ('external', 'internal'):
name = _get(cfg, 'interfaces', option)
if name and not (pathlib.Path('/sys/class/net') / name).exists():
raise ConfigError(
f'interfaces.{option}: interface {name!r} does not exist')
wg_address = _get(cfg, 'wireguard', 'address')
if wg_address:
@@ -199,6 +239,9 @@ def resolve_psk(cfg):
def platform_module(cfg):
"""Import the configured platform module, falling back to the default."""
name = _get(cfg, 'general', 'platform') or vpnrouter_platforms.DEFAULT
if name == PLATFORM_NONE:
# Not normally reached: configure() returns before this when deferred.
name = vpnrouter_platforms.DEFAULT
try:
return vpnrouter_platforms.load(name)
except ModuleNotFoundError:
@@ -216,6 +259,73 @@ def _join(*groups):
return ', '.join(items)
def deferred(cfg):
"""True when platform is none, meaning nothing is to be configured yet."""
return (_get(cfg, 'general', 'platform') or PLATFORM_NONE) == PLATFORM_NONE
def _ip_route(*args):
result = subprocess.run(['ip', *args], capture_output=True, text=True)
return result.stdout if result.returncode == 0 else ''
def detect_interfaces():
"""Work out the external and internal interface names.
Only reached in auto mode, where the operator has accepted that a wrong
guess is possible. The external interface is whichever one carries the
default route; the internal one is the only other addressed interface.
"""
tokens = _ip_route('route', 'get', '1.1.1.1').split()
external = ''
for index, token in enumerate(tokens):
if token == 'dev' and index + 1 < len(tokens):
external = tokens[index + 1]
break
if not external:
raise ConfigError('auto mode: cannot determine the external interface')
candidates = [name for name in _addressed_interfaces() if name != external]
if len(candidates) != 1:
raise ConfigError(
f'auto mode: expected one internal interface, found {len(candidates)}; '
'use mode = interfaces and name them')
return external, candidates[0]
def _addressed_interfaces():
"""Interface names holding at least one IPv4 address, excluding loopback."""
names = []
for line in _ip_route('-o', '-4', 'addr', 'show').splitlines():
fields = line.split()
if len(fields) >= 4 and fields[1] != 'lo' and fields[1] not in names:
names.append(fields[1])
return names
def detect_gateway(iface, address):
"""Derive the next hop on the internal side.
The routing table is the honest source. When it has nothing to say, fall
back to the first host address of the connected subnet, which is a
convention rather than a fact - so say so.
"""
for line in _ip_route('-o', 'route', 'show', 'dev', iface).splitlines():
fields = line.split()
if 'via' in fields:
return fields[fields.index('via') + 1]
for line in _ip_route('-o', '-4', 'addr', 'show', 'dev', iface).splitlines():
fields = line.split()
if len(fields) >= 4 and fields[3].split('/')[0] == address:
network = ipaddress.ip_interface(fields[3]).network
gateway = str(next(network.hosts()))
warn(f'{iface}: no gateway in the routing table, assuming {gateway} '
f'as the first host of {network}')
return gateway
return ''
def interface_addresses(name, setting):
"""IPv4 addresses configured on an interface.
@@ -244,20 +354,42 @@ def interface_addresses(name, setting):
return addresses
def resolve_interfaces(cfg):
"""Return (ext_iface, int_iface, local_addrs, int_addr, int_gateway_ip).
What is read from the system and what is taken verbatim depends entirely on
general.mode. In manual mode nothing below touches the system at all.
"""
mode = _get(cfg, 'general', 'mode') or 'manual'
ext_iface = _get(cfg, 'interfaces', 'external')
int_iface = _get(cfg, 'interfaces', 'internal')
int_addr = _get(cfg, 'local', 'int_addr')
gateway = _get(cfg, 'local', 'int_gateway_ip')
if mode == 'auto':
ext_iface, int_iface = detect_interfaces()
ext_addrs = interface_addresses(ext_iface, 'interfaces.external')
local_addrs = ', '.join(ext_addrs)
if ext_iface and not ext_addrs:
warn(f'{ext_iface} has no IPv4 address yet')
if mode == 'manual':
return ext_iface, int_iface, local_addrs, int_addr, gateway
int_addrs = interface_addresses(int_iface, 'interfaces.internal')
int_addr = int_addrs[0] if int_addrs else ''
if int_iface and not int_addr:
warn(f'{int_iface} has no IPv4 address yet')
gateway = detect_gateway(int_iface, int_addr) if int_addr else ''
return ext_iface, int_iface, local_addrs, int_addr, gateway
def build_context(cfg, local_id_override=None):
"""Assemble the template context from the configuration."""
extras = vpnrouter_platforms.context(platform_module(cfg))
ext_iface = _get(cfg, 'interfaces', 'external')
int_iface = _get(cfg, 'interfaces', 'internal')
ext_addrs = interface_addresses(ext_iface, 'interfaces.external')
int_addrs = interface_addresses(int_iface, 'interfaces.internal')
if ext_iface and not ext_addrs:
warn(f'{ext_iface} has no IPv4 address yet')
local_addrs = ', '.join(ext_addrs)
int_addr = int_addrs[0] if int_addrs else ''
ext_iface, int_iface, local_addrs, int_addr, gateway = resolve_interfaces(cfg)
local_fqdn = _get(cfg, 'wan', 'local_fqdn')
id_mode = _get(cfg, 'wan', 'local_id_mode') or 'fqdn'
@@ -277,7 +409,8 @@ def build_context(cfg, local_id_override=None):
cidr_list = _split_list(local_cidrs)
return {
'platform': _get(cfg, 'general', 'platform') or 'generic',
'platform': _get(cfg, 'general', 'platform') or PLATFORM_NONE,
'mode': _get(cfg, 'general', 'mode') or 'manual',
'wan_iface': ext_iface,
'int_iface': int_iface,
'local_addrs': local_addrs,
@@ -287,10 +420,9 @@ def build_context(cfg, local_id_override=None):
'local_id': local_id,
'local_cidrs': local_cidrs,
'local_cidr_list': cidr_list,
'local_subnet': cidr_list[0] if cidr_list else '',
'local_ts': _join(local_cidrs, extras['EXTRA_LOCAL_TS']),
'int_addr': int_addr,
'int_gateway_ip': _get(cfg, 'local', 'int_gateway_ip'),
'int_gateway_ip': gateway,
'remote_addrs': _get(cfg, 'remote', 'addrs'),
'remote_id': _get(cfg, 'remote', 'id'),
'remote_cidrs': _get(cfg, 'remote', 'cidrs'),
@@ -462,6 +594,12 @@ def configure(cfg=None, local_id_override=None):
"""
if cfg is None:
cfg = load_config()
# platform = none: configuration is deferred. Files are installed and
# nothing is rendered, provisioned or removed until a platform is chosen.
if deferred(cfg):
return None, set()
try:
validate(cfg)
ctx = build_context(cfg, local_id_override=local_id_override)
debian-package/src/usr/share/doc/vpn-router/vpn-router.conf.example
+20 -5
View File
@@ -17,13 +17,25 @@
# and leaves the host reachable and unchanged.
[general]
# Platform module to load: generic, azure or gcp.
platform = generic
# Platform: none, generic, azure or gcp.
# none - configuration is deferred. Files are installed and nothing on
# this machine is changed. Set a real platform when ready.
# generic - configure, with no platform-specific additions.
platform = none
# How much of the network configuration you supply, and therefore how much is
# read from the system:
# manual - interface names, int_addr and int_gateway_ip are all given
# below. Nothing is detected.
# interfaces - the two interface names are given; int_addr and
# int_gateway_ip are read from them.
# auto - nothing is given. The interfaces are identified from the
# routing table. Convenient, and able to get it wrong.
mode = manual
[interfaces]
# The two inputs everything else is built on. Names only: the addresses on
# these interfaces are read from the system, never configured here.
# External faces the untrusted network; internal faces the protected one.
# Required in manual and interfaces mode; worked out for you in auto mode.
external =
internal =
@@ -39,7 +51,10 @@ local_id_mode = fqdn
[local]
# Local subnets advertised into the tunnel, comma-separated.
cidrs =
# Next hop on the internal side for the subnets above.
# This host's own address on the internal network, and the next hop on that
# side for the subnets above. Both are required in manual mode and read from
# the internal interface in the other two.
int_addr =
int_gateway_ip =
[remote]