diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..84888db --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +vault-openvpn diff --git a/example/living-example/README.md b/example/living-example/README.md new file mode 100644 index 0000000..07078ab --- /dev/null +++ b/example/living-example/README.md @@ -0,0 +1,30 @@ +# Example: living-example + +This example is the configuration I'm running for my personal VPN connection. Sure there are some modifications but that are customizations not relevant for this project. + +## How to set up the server? + +- Edit the `cloud-init.yml` file and set your own variables in `/etc/script_env` +- Create a DigitalOcean droplet using this config +- Replace the `myserver.com` part in the `client.conf` with your IP +- Generate a server configuration and put it into `/etc/openvpn/server.conf` +```bash +# vault-openvpn --auto-revoke --pki-mountpoint luzifer_io server edda.openvpn.luzifer.io +server 10.231.0.0 255.255.255.0 +route 10.231.0.0 255.255.255.0 +[...] +``` +- Ensure the server has finished generating `dh.pem` and reload the config: `systemctl restart openvpn` +- Generate a client configuration and put it into Tunnelblick or any other client software you like: +```bash +# vault-openvpn --auto-revoke --pki-mountpoint luzifer_io client knut-ws02.openvpn.luzifer.io +remote myserver.com 1194 udp + +client +nobind +dev tap + + +[...] +``` + diff --git a/example/living-example/client.conf b/example/living-example/client.conf new file mode 100644 index 0000000..0a2d611 --- /dev/null +++ b/example/living-example/client.conf @@ -0,0 +1,18 @@ +remote myserver.com 1194 udp + +client +nobind +dev tap + + +{{ .CertAuthority }} + + + +{{ .Certificate }} + + + +{{ .PrivateKey }} + + diff --git a/example/living-example/cloud-init.yml b/example/living-example/cloud-init.yml new file mode 100644 index 0000000..6df32a7 --- /dev/null +++ b/example/living-example/cloud-init.yml @@ -0,0 +1,45 @@ +#cloud-config + +packages: + - openvpn + +write_files: + - content: | + VAULT_ADDR="https://..." + PKI_PATH="${VAULT_ADDR}/v1/luzifer_io" + path: /etc/script_env + owner: root:root + permissions: '0600' + + - content: | + #!/bin/bash -ex + source /etc/script_env + + sed -i 's/#AUTOSTART="all"/AUTOSTART="all"/' /etc/default/openvpn + systemctl daemon-reload + + openssl dhparam -out /etc/openvpn/dh2048.pem 2048 + /usr/local/bin/refresh_crl + path: /tmp/setup.sh + owner: root:root + permissions: '0755' + + - content: | + #!/bin/bash -ex + source /etc/script_env + + curl -sSLo /tmp/crl.pem ${PKI_PATH}/crl/pem + if ! ( diff -wq /etc/openvpn/crl.pem /tmp/crl.pem ); then + mv /tmp/crl.pem /etc/openvpn/crl.pem + fi + path: /usr/local/bin/refresh_crl + owner: root:root + permissions: '0755' + + - content: | + */5 * * * * root /usr/local/bin/refresh_crl + path: /etc/cron.d/openvpn + owner: root:root + +runcmd: + - [ /tmp/setup.sh ] diff --git a/example/living-example/server.conf b/example/living-example/server.conf new file mode 100644 index 0000000..c1bd435 --- /dev/null +++ b/example/living-example/server.conf @@ -0,0 +1,34 @@ +server 10.231.0.0 255.255.255.0 +route 10.231.0.0 255.255.255.0 + +keepalive 5 30 +persist-key +persist-tun + +proto udp +port 1194 +dev tap +status /var/log/openvpn-status.log + +client-to-client +ifconfig-pool-persist /etc/openvpn/ipp.txt + +verb 3 + +push dhcp-option DNS 8.8.8.8 +push dhcp-option DNS 8.8.4.4 + +dh /etc/openvpn/dh2048.pem +crl-verify /etc/openvpn/crl.pem + + +{{ .CertAuthority }} + + + +{{ .Certificate }} + + + +{{ .PrivateKey }} + diff --git a/example/openvpn-sample/client.conf b/example/openvpn-sample/client.conf new file mode 100644 index 0000000..63ca131 --- /dev/null +++ b/example/openvpn-sample/client.conf @@ -0,0 +1,131 @@ +############################################## +# Sample client-side OpenVPN 2.0 config file # +# for connecting to multi-client server. # +# # +# This configuration can be used by multiple # +# clients, however each client should have # +# its own cert and key files. # +# # +# On Windows, you might want to rename this # +# file so it has a .ovpn extension # +############################################## + +# Specify that we are a client and that we +# will be pulling certain config file directives +# from the server. +client + +# Use the same setting as you are using on +# the server. +# On most systems, the VPN will not function +# unless you partially or fully disable +# the firewall for the TUN/TAP interface. +;dev tap +dev tun + +# Windows needs the TAP-Windows adapter name +# from the Network Connections panel +# if you have more than one. On XP SP2, +# you may need to disable the firewall +# for the TAP adapter. +;dev-node MyTap + +# Are we connecting to a TCP or +# UDP server? Use the same setting as +# on the server. +;proto tcp +proto udp + +# The hostname/IP and port of the server. +# You can have multiple remote entries +# to load balance between the servers. +remote my-server-1 1194 +;remote my-server-2 1194 + +# Choose a random host from the remote +# list for load-balancing. Otherwise +# try hosts in the order specified. +;remote-random + +# Keep trying indefinitely to resolve the +# host name of the OpenVPN server. Very useful +# on machines which are not permanently connected +# to the internet such as laptops. +resolv-retry infinite + +# Most clients don't need to bind to +# a specific local port number. +nobind + +# Downgrade privileges after initialization (non-Windows only) +;user nobody +;group nobody + +# Try to preserve some state across restarts. +persist-key +persist-tun + +# If you are connecting through an +# HTTP proxy to reach the actual OpenVPN +# server, put the proxy server/IP and +# port number here. See the man page +# if your proxy server requires +# authentication. +;http-proxy-retry # retry on connection failures +;http-proxy [proxy server] [proxy port #] + +# Wireless networks often produce a lot +# of duplicate packets. Set this flag +# to silence duplicate packet warnings. +;mute-replay-warnings + +# SSL/TLS parms. +# See the server config file for more +# description. It's best to use +# a separate .crt/.key file pair +# for each client. A single ca +# file can be used for all clients. + +{{ .CertAuthority }} + + + +{{ .Certificate }} + + + +{{ .PrivateKey }} + + +# Verify server certificate by checking +# that the certicate has the nsCertType +# field set to "server". This is an +# important precaution to protect against +# a potential attack discussed here: +# http://openvpn.net/howto.html#mitm +# +# To use this feature, you will need to generate +# your server certificates with the nsCertType +# field set to "server". The build-key-server +# script in the easy-rsa folder will do this. +;ns-cert-type server + +# If a tls-auth key is used on the server +# then every client must also have the key. +;tls-auth ta.key 1 + +# Select a cryptographic cipher. +# If the cipher option is used on the server +# then you must also specify it here. +;cipher x + +# Enable compression on the VPN link. +# Don't enable this unless it is also +# enabled in the server config file. +comp-lzo + +# Set log file verbosity. +verb 3 + +# Silence repeating messages +;mute 20 diff --git a/example/openvpn-sample/server.conf b/example/openvpn-sample/server.conf new file mode 100644 index 0000000..6eb0a9e --- /dev/null +++ b/example/openvpn-sample/server.conf @@ -0,0 +1,299 @@ +################################################# +# Sample OpenVPN 2.0 config file for # +# multi-client server. # +# # +# This file is for the server side # +# of a many-clients one-server # +# OpenVPN configuration. # +# # +# OpenVPN also supports # +# single-machine single-machine # +# configurations (See the Examples page # +# on the web site for more info). # +# # +# This config should work on Windows # +# or Linux/BSD systems. Remember on # +# Windows to quote pathnames and use # +# double backslashes, e.g.: # +# "C:\\Program Files\\OpenVPN\\config\\foo.key" # +# # +# Comments are preceded with '#' or ';' # +################################################# + +# Which local IP address should OpenVPN +# listen on? (optional) +;local a.b.c.d + +# Which TCP/UDP port should OpenVPN listen on? +# If you want to run multiple OpenVPN instances +# on the same machine, use a different port +# number for each one. You will need to +# open up this port on your firewall. +port 1194 + +# TCP or UDP server? +;proto tcp +proto udp + +# "dev tun" will create a routed IP tunnel, +# "dev tap" will create an ethernet tunnel. +# Use "dev tap0" if you are ethernet bridging +# and have precreated a tap0 virtual interface +# and bridged it with your ethernet interface. +# If you want to control access policies +# over the VPN, you must create firewall +# rules for the the TUN/TAP interface. +# On non-Windows systems, you can give +# an explicit unit number, such as tun0. +# On Windows, use "dev-node" for this. +# On most systems, the VPN will not function +# unless you partially or fully disable +# the firewall for the TUN/TAP interface. +;dev tap +dev tun + +# Windows needs the TAP-Windows adapter name +# from the Network Connections panel if you +# have more than one. On XP SP2 or higher, +# you may need to selectively disable the +# Windows firewall for the TAP adapter. +# Non-Windows systems usually don't need this. +;dev-node MyTap + +# SSL/TLS root certificate (ca), certificate +# (cert), and private key (key). Each client +# and the server must have their own cert and +# key file. The server and all clients will +# use the same ca file. +# +# See the "easy-rsa" directory for a series +# of scripts for generating RSA certificates +# and private keys. Remember to use +# a unique Common Name for the server +# and each of the client certificates. +# +# Any X509 key management system can be used. +# OpenVPN can also use a PKCS #12 formatted key file +# (see "pkcs12" directive in man page). + +{{ .CertAuthority }} + + + +{{ .Certificate }} + + + +{{ .PrivateKey }} + + +# Diffie hellman parameters. +# Generate your own with: +# openssl dhparam -out dh1024.pem 1024 +# Substitute 2048 for 1024 if you are using +# 2048 bit keys. +dh dh1024.pem + +# Configure server mode and supply a VPN subnet +# for OpenVPN to draw client addresses from. +# The server will take 10.8.0.1 for itself, +# the rest will be made available to clients. +# Each client will be able to reach the server +# on 10.8.0.1. Comment this line out if you are +# ethernet bridging. See the man page for more info. +server 10.8.0.0 255.255.255.0 + +# Maintain a record of client virtual IP address +# associations in this file. If OpenVPN goes down or +# is restarted, reconnecting clients can be assigned +# the same virtual IP address from the pool that was +# previously assigned. +ifconfig-pool-persist ipp.txt + +# Configure server mode for ethernet bridging. +# You must first use your OS's bridging capability +# to bridge the TAP interface with the ethernet +# NIC interface. Then you must manually set the +# IP/netmask on the bridge interface, here we +# assume 10.8.0.4/255.255.255.0. Finally we +# must set aside an IP range in this subnet +# (start=10.8.0.50 end=10.8.0.100) to allocate +# to connecting clients. Leave this line commented +# out unless you are ethernet bridging. +;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100 + +# Push routes to the client to allow it +# to reach other private subnets behind +# the server. Remember that these +# private subnets will also need +# to know to route the OpenVPN client +# address pool (10.8.0.0/255.255.255.0) +# back to the OpenVPN server. +;push "route 192.168.10.0 255.255.255.0" +;push "route 192.168.20.0 255.255.255.0" + +# To assign specific IP addresses to specific +# clients or if a connecting client has a private +# subnet behind it that should also have VPN access, +# use the subdirectory "ccd" for client-specific +# configuration files (see man page for more info). + +# EXAMPLE: Suppose the client +# having the certificate common name "Thelonious" +# also has a small subnet behind his connecting +# machine, such as 192.168.40.128/255.255.255.248. +# First, uncomment out these lines: +;client-config-dir ccd +;route 192.168.40.128 255.255.255.248 +# Then create a file ccd/Thelonious with this line: +# iroute 192.168.40.128 255.255.255.248 +# This will allow Thelonious' private subnet to +# access the VPN. This example will only work +# if you are routing, not bridging, i.e. you are +# using "dev tun" and "server" directives. + +# EXAMPLE: Suppose you want to give +# Thelonious a fixed VPN IP address of 10.9.0.1. +# First uncomment out these lines: +;client-config-dir ccd +;route 10.9.0.0 255.255.255.252 +# Then add this line to ccd/Thelonious: +# ifconfig-push 10.9.0.1 10.9.0.2 + +# Suppose that you want to enable different +# firewall access policies for different groups +# of clients. There are two methods: +# (1) Run multiple OpenVPN daemons, one for each +# group, and firewall the TUN/TAP interface +# for each group/daemon appropriately. +# (2) (Advanced) Create a script to dynamically +# modify the firewall in response to access +# from different clients. See man +# page for more info on learn-address script. +;learn-address ./script + +# If enabled, this directive will configure +# all clients to redirect their default +# network gateway through the VPN, causing +# all IP traffic such as web browsing and +# and DNS lookups to go through the VPN +# (The OpenVPN server machine may need to NAT +# the TUN/TAP interface to the internet in +# order for this to work properly). +# CAVEAT: May break client's network config if +# client's local DHCP server packets get routed +# through the tunnel. Solution: make sure +# client's local DHCP server is reachable via +# a more specific route than the default route +# of 0.0.0.0/0.0.0.0. +;push "redirect-gateway" + +# Certain Windows-specific network settings +# can be pushed to clients, such as DNS +# or WINS server addresses. CAVEAT: +# http://openvpn.net/faq.html#dhcpcaveats +;push "dhcp-option DNS 10.8.0.1" +;push "dhcp-option WINS 10.8.0.1" + +# Uncomment this directive to allow different +# clients to be able to "see" each other. +# By default, clients will only see the server. +# To force clients to only see the server, you +# will also need to appropriately firewall the +# server's TUN/TAP interface. +;client-to-client + +# Uncomment this directive if multiple clients +# might connect with the same certificate/key +# files or common names. This is recommended +# only for testing purposes. For production use, +# each client should have its own certificate/key +# pair. +# +# IF YOU HAVE NOT GENERATED INDIVIDUAL +# CERTIFICATE/KEY PAIRS FOR EACH CLIENT, +# EACH HAVING ITS OWN UNIQUE "COMMON NAME", +# UNCOMMENT THIS LINE OUT. +;duplicate-cn + +# The keepalive directive causes ping-like +# messages to be sent back and forth over +# the link so that each side knows when +# the other side has gone down. +# Ping every 10 seconds, assume that remote +# peer is down if no ping received during +# a 120 second time period. +keepalive 10 120 + +# For extra security beyond that provided +# by SSL/TLS, create an "HMAC firewall" +# to help block DoS attacks and UDP port flooding. +# +# Generate with: +# openvpn --genkey --secret ta.key +# +# The server and each client must have +# a copy of this key. +# The second parameter should be '0' +# on the server and '1' on the clients. +;tls-auth ta.key 0 # This file is secret + +# Select a cryptographic cipher. +# This config item must be copied to +# the client config file as well. +;cipher BF-CBC # Blowfish (default) +;cipher AES-128-CBC # AES +;cipher DES-EDE3-CBC # Triple-DES + +# Enable compression on the VPN link. +# If you enable it here, you must also +# enable it in the client config file. +comp-lzo + +# The maximum number of concurrently connected +# clients we want to allow. +;max-clients 100 + +# It's a good idea to reduce the OpenVPN +# daemon's privileges after initialization. +# +# You can uncomment this out on +# non-Windows systems. +;user nobody +;group nobody + +# The persist options will try to avoid +# accessing certain resources on restart +# that may no longer be accessible because +# of the privilege downgrade. +persist-key +persist-tun + +# Output a short status file showing +# current connections, truncated +# and rewritten every minute. +status openvpn-status.log + +# By default, log messages will go to the syslog (or +# on Windows, if running as a service, they will go to +# the "\Program Files\OpenVPN\log" directory). +# Use log or log-append to override this default. +# "log" will truncate the log file on OpenVPN startup, +# while "log-append" will append to it. Use one +# or the other (but not both). +;log openvpn.log +;log-append openvpn.log + +# Set the appropriate level of log +# file verbosity. +# +# 0 is silent, except for fatal errors +# 4 is reasonable for general usage +# 5 and 6 can help to debug connection problems +# 9 is extremely verbose +verb 3 + +# Silence repeating messages. At most 20 +# sequential messages of the same message +# category will be output to the log. +;mute 20 diff --git a/main.go b/main.go new file mode 100644 index 0000000..9f4b7c7 --- /dev/null +++ b/main.go @@ -0,0 +1,234 @@ +package main + +import ( + "crypto/x509" + "encoding/pem" + "errors" + "fmt" + "io/ioutil" + "log" + "os" + "strings" + "text/template" + "time" + + "github.com/Luzifer/go_helpers/str" + "github.com/Luzifer/rconfig" + "github.com/hashicorp/vault/api" + homedir "github.com/mitchellh/go-homedir" +) + +const ( + actionRevoke = "revoke" + actionMakeClientConfig = "client" + actionMakeServerConfig = "server" +) + +var ( + cfg = struct { + VaultAddress string `flag:"vault-addr" env:"VAULT_ADDR" default:"https://127.0.0.1:8200" description:"Vault API address"` + VaultToken string `flag:"vault-token" env:"VAULT_TOKEN" vardefault:"vault-token" description:"Specify a token to use instead of app-id auth"` + + PKIMountPoint string `flag:"pki-mountpoint" default:"/pki" description:"Path the PKI provider is mounted to"` + PKIRole string `flag:"pki-role" default:"openvpn" description:"Role defined in the PKI usable by the token and able to write the specified FQDN"` + + AutoRevoke bool `flag:"auto-revoke" default:"false" description:"Automatically revoke older certificates for this FQDN"` + CertTTL time.Duration `flag:"ttl" default:"8760h" description:"Set the TTL for this certificate"` + + VersionAndExit bool `flag:"version" default:"false" description:"Prints current version and exits"` + }{} + + version = "dev" + + client *api.Client +) + +type templateVars struct { + CertAuthority string + Certificate string + PrivateKey string +} + +func vaultTokenFromDisk() string { + vf, err := homedir.Expand("~/.vault-token") + if err != nil { + return "" + } + + data, err := ioutil.ReadFile(vf) + if err != nil { + return "" + } + + return string(data) +} + +func init() { + rconfig.SetVariableDefaults(map[string]string{ + "vault-token": vaultTokenFromDisk(), + }) + + if err := rconfig.Parse(&cfg); err != nil { + log.Fatalf("Unable to parse commandline options: %s", err) + } + + if cfg.VersionAndExit { + fmt.Printf("vault-openvpn %s\n", version) + os.Exit(0) + } + + if cfg.VaultToken == "" { + log.Fatalf("[ERR] You need to set vault-token") + } +} + +func main() { + if len(rconfig.Args()) != 3 { + fmt.Println("Usage: vault-openvpn [options] ") + fmt.Println(" actions: client / server / revoke") + os.Exit(1) + } + + action := rconfig.Args()[1] + fqdn := rconfig.Args()[2] + + if !str.StringInSlice(action, []string{actionRevoke, actionMakeClientConfig, actionMakeServerConfig}) { + log.Fatalf("Unknown action: %s", action) + } + + var err error + client, err = api.NewClient(&api.Config{ + Address: cfg.VaultAddress, + }) + + if err != nil { + log.Fatalf("Could not create Vault client: %s", err) + } + + client.SetToken(cfg.VaultToken) + + if cfg.AutoRevoke || action == actionRevoke { + if err := revokeOlderCertificate(fqdn); err != nil { + log.Fatalf("Could not revoke certificate: %s", err) + } + } + + if action != actionMakeClientConfig && action != actionMakeServerConfig { + return + } + + tplName := "client.conf" + if action == actionMakeServerConfig { + tplName = "server.conf" + } + + caCert, err := getCACert() + if err != nil { + log.Fatalf("Could not load CA certificate: %s", err) + } + + tplv, err := generateCertificate(fqdn) + if err != nil { + log.Fatalf("Could not generate new certificate: %s", err) + } + + tplv.CertAuthority = caCert + + if err := renderTemplate(tplName, tplv); err != nil { + log.Fatalf("Could not render configuration: %s", err) + } +} + +func renderTemplate(tplName string, tplv *templateVars) error { + raw, err := ioutil.ReadFile(tplName) + if err != nil { + return err + } + + tpl, err := template.New("tpl").Parse(string(raw)) + if err != nil { + return err + } + + return tpl.Execute(os.Stdout, tplv) +} + +func revokeOlderCertificate(fqdn string) error { + path := strings.Join([]string{strings.Trim(cfg.PKIMountPoint, "/"), "certs"}, "/") + secret, err := client.Logical().List(path) + if err != nil { + return err + } + + if secret.Data == nil { + return errors.New("Got no data from backend") + } + + for _, serial := range secret.Data["keys"].([]interface{}) { + path := strings.Join([]string{strings.Trim(cfg.PKIMountPoint, "/"), "cert", serial.(string)}, "/") + cs, err := client.Logical().Read(path) + if err != nil { + errors.New("Unable to read certificate: " + err.Error()) + } + + cn, err := commonNameFromCertificate(cs.Data["certificate"].(string)) + if err != nil { + return err + } + + log.Printf("Found certificate %s with CN %s", serial, cn) + + if cn == fqdn { + path := strings.Join([]string{strings.Trim(cfg.PKIMountPoint, "/"), "revoke"}, "/") + if _, err := client.Logical().Write(path, map[string]interface{}{ + "serial_number": serial.(string), + }); err != nil { + return errors.New("Revoke of serial " + serial.(string) + " failed: " + err.Error()) + } + log.Printf("Revoked certificate %s", serial) + } + } + + return nil +} + +func commonNameFromCertificate(pemString string) (string, error) { + data, _ := pem.Decode([]byte(pemString)) + cert, err := x509.ParseCertificate(data.Bytes) + if err != nil { + return "", err + } + + return cert.Subject.CommonName, nil +} + +func getCACert() (string, error) { + path := strings.Join([]string{strings.Trim(cfg.PKIMountPoint, "/"), "cert", "ca"}, "/") + cs, err := client.Logical().Read(path) + if err != nil { + errors.New("Unable to read certificate: " + err.Error()) + } + + return cs.Data["certificate"].(string), nil +} + +func generateCertificate(fqdn string) (*templateVars, error) { + path := strings.Join([]string{strings.Trim(cfg.PKIMountPoint, "/"), "issue", cfg.PKIRole}, "/") + secret, err := client.Logical().Write(path, map[string]interface{}{ + "common_name": fqdn, + "ttl": cfg.CertTTL.String(), + }) + + if err != nil { + return nil, err + } + + if secret.Data == nil { + return nil, errors.New("Got no data from backend") + } + + return &templateVars{ + Certificate: secret.Data["certificate"].(string), + PrivateKey: secret.Data["private_key"].(string), + }, nil +}