# ==============================================================================
#
#   TELEMT — Advanced Rust-based Telegram MTProto Proxy
#   Full Configuration Reference
#
#   This file is both a working config and a complete documentation.
#   Every parameter is explained. Read it top to bottom before deploying.
#
#   Quick Start:
#     1. Set [server].port to your desired port (443 recommended)
#     2. Generate a secret: openssl rand -hex 16
#     3. Put it in [access.users] under a name you choose
#     4. Set [censorship].tls_domain to a popular unblocked HTTPS site
#     5. Set your public IP in [general].middle_proxy_nat_ip
#        and [general.links].public_host
#     6. Set announce IP in [[server.listeners]]
#     7. Run Telemt. It prints a tg:// link. Send it to your users.
#
#   Modes of Operation:
#     Direct Mode  (use_middle_proxy = false)
#       Connects straight to Telegram DCs via TCP. Simple, fast, low overhead.
#       No ad_tag support. No CDN DC support (203, etc).
#
#     Middle-Proxy Mode  (use_middle_proxy = true)
#       Connects to Telegram Middle-End servers via RPC protocol.
#       Required for ad_tag monetization and CDN support.
#       Requires proxy_secret_path and a valid public IP.
#
# ==============================================================================


# ==============================================================================
# LEGACY TOP-LEVEL FIELDS
# ==============================================================================

# Deprecated. Use [general.links].show instead.
# Accepts "*" for all users, or an array like ["alice", "bob"].
show_link = ["0"]

# Fallback Datacenter index (1-5) when a client requests an unknown DC ID.
# DC 2 is Amsterdam (Europe), closest for most CIS users.
# default_dc = 2


# ==============================================================================
# GENERAL SETTINGS
# ==============================================================================

[general]

# ------------------------------------------------------------------------------
# Core Protocol
# ------------------------------------------------------------------------------

# Coalesce the MTProto handshake and first data payload into a single TCP packet.
# Significantly reduces connection latency. No reason to disable.
fast_mode = true

# How the proxy connects to Telegram servers.
# false = Direct TCP to Telegram DCs (simple, low overhead)
# true  = Middle-End RPC protocol (required for ad_tag and CDN DCs)
use_middle_proxy = true

# 32-char hex Ad-Tag from @MTProxybot for sponsored channel injection.
# Only works when use_middle_proxy = true.
# Obtain yours: message @MTProxybot on Telegram, register your proxy.
# ad_tag = "00000000000000000000000000000000"

# ------------------------------------------------------------------------------
# Middle-End Authentication
# ------------------------------------------------------------------------------

# Path to the Telegram infrastructure AES key file.
# Auto-downloaded from https://core.telegram.org/getProxySecret on first run.
# This key authenticates your proxy with Middle-End servers.
proxy_secret_path = "proxy-secret"

# ------------------------------------------------------------------------------
# Public IP Configuration (Critical for Middle-Proxy Mode)
# ------------------------------------------------------------------------------

# Your server's PUBLIC IPv4 address.
# Middle-End servers need this for the cryptographic Key Derivation Function.
# If your server has a direct public IP, set it here.
# If behind NAT (AWS, Docker, etc.), this MUST be your external IP.
# If omitted, Telemt uses STUN to auto-detect (see middle_proxy_nat_probe).
# middle_proxy_nat_ip = "203.0.113.10"

# Auto-detect public IP via STUN servers defined in [network].
# Set to false if you hardcoded middle_proxy_nat_ip above.
# Set to true if you want automatic detection.
middle_proxy_nat_probe = true

# ------------------------------------------------------------------------------
# Middle-End Connection Pool
# ------------------------------------------------------------------------------

# Number of persistent multiplexed RPC connections to ME servers.
# All client traffic is routed through these "fat pipes".
# 8 handles thousands of concurrent users comfortably.
middle_proxy_pool_size = 8

# Legacy field. Connections kept initialized but idle as warm standby.
middle_proxy_warm_standby = 16

# ------------------------------------------------------------------------------
# Middle-End Keepalive
# Telegram ME servers aggressively kill idle TCP connections.
# These settings send periodic RPC_PING frames to keep pipes alive.
# ------------------------------------------------------------------------------

me_keepalive_enabled = true

# Base interval between pings in seconds.
me_keepalive_interval_secs = 25

# Random jitter added to interval to prevent all connections pinging simultaneously.
me_keepalive_jitter_secs = 5

# Randomize ping payload bytes to prevent DPI from fingerprinting ping patterns.
me_keepalive_payload_random = true

# ------------------------------------------------------------------------------
# Client-Side Limits
# ------------------------------------------------------------------------------

# Max buffered ciphertext per client (bytes) when upstream is slow.
# Acts as backpressure to prevent memory exhaustion. 256KB is safe.
crypto_pending_buffer = 262144

# Maximum single MTProto frame size from client. 16MB is protocol standard.
max_client_frame = 16777216

# ------------------------------------------------------------------------------
# Crypto Desynchronization Logging
# Desync errors usually mean DPI/GFW is tampering with connections.
# ------------------------------------------------------------------------------

# true  = full forensics (trace ID, IP hash, hex dumps) for EVERY desync event
# false = deduplicated logging, one entry per time window (prevents log spam)
# Set true if you are actively debugging DPI interference.
desync_all_full = true

# ------------------------------------------------------------------------------
# Beobachten — Built-in Honeypot / Active Probe Tracker
# Tracks IPs that fail handshakes or behave like TLS scanners.
# Output file can be fed into fail2ban or iptables for auto-blocking.
# ------------------------------------------------------------------------------

beobachten = true

# How long (minutes) to remember a suspicious IP before expiring it.
beobachten_minutes = 30

# How often (seconds) to flush tracker state to disk.
beobachten_flush_secs = 15

# File path for the tracker output.
beobachten_file = "cache/beobachten.txt"

# ------------------------------------------------------------------------------
# Hardswap — Zero-Downtime ME Pool Rotation
# When Telegram updates ME server IPs, Hardswap creates a completely new pool,
# waits until it is fully ready, migrates traffic, then kills the old pool.
# Users experience zero interruption.
# ------------------------------------------------------------------------------

hardswap = true

# ------------------------------------------------------------------------------
# ME Pool Warmup Staggering
# When creating a new pool, connections are opened one by one with delays
# to avoid a burst of SYN packets that could trigger ISP flood protection.
# ------------------------------------------------------------------------------

me_warmup_stagger_enabled = true

# Delay between each connection creation (milliseconds).
me_warmup_step_delay_ms = 500

# Random jitter added to the delay (milliseconds).
me_warmup_step_jitter_ms = 300

# ------------------------------------------------------------------------------
# ME Reconnect Backoff
# If an ME server drops the connection, Telemt retries with this strategy.
# ------------------------------------------------------------------------------

# Max simultaneous reconnect attempts per DC.
me_reconnect_max_concurrent_per_dc = 8

# Exponential backoff base (milliseconds).
me_reconnect_backoff_base_ms = 500

# Backoff ceiling (milliseconds). Will never wait longer than this.
me_reconnect_backoff_cap_ms = 30000

# Number of instant retries before switching to exponential backoff.
me_reconnect_fast_retry_count = 12

# ------------------------------------------------------------------------------
# NAT Mismatch Behavior
# If STUN-detected IP differs from local interface IP (you are behind NAT).
# false = abort ME mode (safe default)
# true  = force ME mode anyway (use if you know your NAT setup is correct)
# ------------------------------------------------------------------------------

stun_iface_mismatch_ignore = false

# ------------------------------------------------------------------------------
# Logging
# ------------------------------------------------------------------------------

# File to log unknown DC requests (DC IDs outside standard 1-5).
unknown_dc_log_path = "unknown-dc.txt"

# Verbosity: "debug" | "verbose" | "normal" | "silent"
log_level = "normal"

# Disable ANSI color codes in log output (useful for file logging).
disable_colors = false

# ------------------------------------------------------------------------------
# FakeTLS Record Sizing
# Buffer small MTProto packets into larger TLS records to mimic real HTTPS.
# Real HTTPS servers send records close to MTU size (~1400 bytes).
# A stream of tiny TLS records is a strong DPI signal.
# Set to 0 to disable. Set to 1400 for realistic HTTPS emulation.
# ------------------------------------------------------------------------------

fast_mode_min_tls_record = 1400

# ------------------------------------------------------------------------------
# Periodic Updates
# ------------------------------------------------------------------------------

# How often (seconds) to re-fetch ME server lists and proxy secrets
# from core.telegram.org. Keeps your proxy in sync with Telegram infrastructure.
update_every = 300

# How often (seconds) to force a Hardswap even if the ME map is unchanged.
# Shorter intervals mean shorter-lived TCP flows, harder for DPI to profile.
me_reinit_every_secs = 600

# ------------------------------------------------------------------------------
# Hardswap Warmup Tuning
# Fine-grained control over how the new pool is warmed up before traffic switch.
# ------------------------------------------------------------------------------

me_hardswap_warmup_delay_min_ms = 1000
me_hardswap_warmup_delay_max_ms = 2000
me_hardswap_warmup_extra_passes = 3
me_hardswap_warmup_pass_backoff_base_ms = 500

# ------------------------------------------------------------------------------
# Config Update Debouncing
# Telegram sometimes pushes transient/broken configs. Debouncing requires
# N consecutive identical fetches before applying a change.
# ------------------------------------------------------------------------------

# ME server list must be identical for this many fetches before applying.
me_config_stable_snapshots = 2

# Minimum seconds between config applications.
me_config_apply_cooldown_secs = 300

# Proxy secret must be identical for this many fetches before applying.
proxy_secret_stable_snapshots = 2

# ------------------------------------------------------------------------------
# Proxy Secret Rotation
# ------------------------------------------------------------------------------

# Apply newly downloaded secrets at runtime without restart.
proxy_secret_rotate_runtime = true

# Maximum acceptable secret length (bytes). Rejects abnormally large secrets.
proxy_secret_len_max = 256

# ------------------------------------------------------------------------------
# Hardswap Drain Settings
# Controls graceful shutdown of old ME connections during pool rotation.
# ------------------------------------------------------------------------------

# Seconds to keep old connections alive for in-flight data before force-closing.
me_pool_drain_ttl_secs = 90

# Minimum ratio of healthy connections in new pool before draining old pool.
# 0.8 = at least 80% of new pool must be ready.
me_pool_min_fresh_ratio = 0.8

# Maximum seconds to wait for drain to complete before force-killing.
me_reinit_drain_timeout_secs = 120

# ------------------------------------------------------------------------------
# NTP Clock Check
# MTProto uses timestamps. Clock drift > 30 seconds breaks handshakes.
# Telemt checks on startup and warns if out of sync.
# ------------------------------------------------------------------------------

ntp_check = true
ntp_servers = ["pool.ntp.org"]

# ------------------------------------------------------------------------------
# Auto-Degradation
# If ME servers become completely unreachable (ISP blocking),
# automatically fall back to Direct Mode so users stay connected.
# ------------------------------------------------------------------------------

auto_degradation_enabled = true

# Number of DC groups that must be unreachable before triggering fallback.
degradation_min_unavailable_dc_groups = 2


# ==============================================================================
# ALLOWED CLIENT PROTOCOLS
# Only enable what you need. In censored regions, TLS-only is safest.
# ==============================================================================

[general.modes]

# Classic MTProto. Unobfuscated length prefixes. Trivially detected by DPI.
# No reason to enable unless you have ancient clients.
classic = false

# Obfuscated MTProto with randomized padding. Better than classic, but
# still detectable by statistical analysis of packet sizes.
secure = false

# FakeTLS (ee-secrets). Wraps MTProto in TLS 1.3 framing.
# To DPI, it looks like a normal HTTPS connection.
# This should be the ONLY enabled mode in censored environments.
tls = true


# ==============================================================================
# STARTUP LINK GENERATION
# Controls what tg:// invite links are printed to console on startup.
# ==============================================================================

[general.links]

# Which users to generate links for.
# "*" = all users, or an array like ["alice", "bob"].
show = "*"

# IP or domain to embed in the tg:// link.
# If omitted, Telemt uses STUN to auto-detect.
# Set this to your server's public IP or domain for reliable links.
# public_host = "proxy.example.com"

# Port to embed in the tg:// link.
# If omitted, uses [server].port.
# public_port = 443


# ==============================================================================
# NETWORK & IP RESOLUTION
# ==============================================================================

[network]

# Enable IPv4 for outbound connections to Telegram.
ipv4 = true

# Enable IPv6 for outbound connections to Telegram.
ipv6 = false

# Prefer IPv4 (4) or IPv6 (6) when both are available.
prefer = 4

# Experimental: use both IPv4 and IPv6 ME servers simultaneously.
# May improve reliability but doubles connection count.
multipath = false

# STUN servers for external IP discovery.
# Used for Middle-Proxy KDF (if nat_probe=true) and link generation.
stun_servers = [
    "stun.l.google.com:5349",
    "stun1.l.google.com:3478",
    "stun.gmx.net:3478",
    "stun.l.google.com:19302"
]

# If UDP STUN is blocked, attempt TCP-based STUN as fallback.
stun_tcp_fallback = true

# If all STUN fails, use HTTP APIs to discover public IP.
http_ip_detect_urls = [
    "https://ifconfig.me/ip",
    "https://api.ipify.org"
]

# Cache discovered public IP to this file to survive restarts.
cache_public_ip_path = "cache/public_ip.txt"


# ==============================================================================
# SERVER BINDING & METRICS
# ==============================================================================

[server]

# TCP port to listen on.
# 443 is recommended (looks like normal HTTPS traffic).
port = 443

# IPv4 bind address. "0.0.0.0" = all interfaces.
listen_addr_ipv4 = "0.0.0.0"

# IPv6 bind address. "::" = all interfaces.
listen_addr_ipv6 = "::"

# Unix socket listener (for reverse proxy setups with Nginx/HAProxy).
# listen_unix_sock = "/var/run/telemt.sock"
# listen_unix_sock_perm = "0660"

# Enable PROXY protocol header parsing.
# Set true ONLY if Telemt is behind HAProxy/Nginx that injects PROXY headers.
# If enabled without a proxy in front, clients will fail to connect.
proxy_protocol = false

# Prometheus metrics HTTP endpoint port.
# Uncomment to enable. Access at http://your-server:9090/metrics
# metrics_port = 9090

# IP ranges allowed to access the metrics endpoint.
metrics_whitelist = [
    "127.0.0.1/32",
    "::1/128"
]

# ------------------------------------------------------------------------------
# Listener Overrides
# Define explicit listeners with specific bind IPs and announce IPs.
# The announce IP is what gets embedded in tg:// links and sent to ME servers.
# You MUST set announce to your server's public IP for ME mode to work.
# ------------------------------------------------------------------------------

# [[server.listeners]]
# ip = "0.0.0.0"
# announce = "203.0.113.10"
# reuse_allow = false


# ==============================================================================
# TIMEOUTS (seconds unless noted)
# ==============================================================================

[timeouts]

# Maximum time for client to complete FakeTLS + MTProto handshake.
client_handshake = 15

# Maximum time to establish TCP connection to upstream Telegram DC.
tg_connect = 10

# TCP keepalive interval for client connections.
client_keepalive = 60

# Maximum client inactivity before dropping the connection.
client_ack = 300

# Instant retry count for a single ME endpoint before giving up on it.
me_one_retry = 3

# Timeout (milliseconds) for a single ME endpoint connection attempt.
me_one_timeout_ms = 1500


# ==============================================================================
# ANTI-CENSORSHIP / FAKETLS / MASKING
# This is where Telemt becomes invisible to Deep Packet Inspection.
# ==============================================================================

[censorship]

# ------------------------------------------------------------------------------
# TLS Domain Fronting
# The SNI (Server Name Indication) your proxy presents to connecting clients.
# Must be a popular, unblocked HTTPS website in your target country.
# DPI sees traffic to this domain. Choose carefully.
# Good choices: major CDNs, banks, government sites, search engines.
# Bad choices: obscure sites, already-blocked domains.
# ------------------------------------------------------------------------------

tls_domain = "www.google.com"

# ------------------------------------------------------------------------------
# Active Probe Masking
# When someone connects but fails the MTProto handshake (wrong secret),
# they might be an ISP active prober testing if this is a proxy.
#
# mask = false: drop the connection (prober knows something is here)
# mask = true:  transparently proxy them to mask_host (prober sees a real website)
#
# With mask enabled, your server is indistinguishable from a real web server
# to anyone who doesn't have the correct secret.
# ------------------------------------------------------------------------------

mask = true

# The real web server to forward failed handshakes to.
# If omitted, defaults to tls_domain.
# mask_host = "www.google.com"

# Port on the mask host to connect to.
mask_port = 443

# Inject PROXY protocol header when forwarding to mask host.
# 0 = disabled, 1 = v1, 2 = v2. Leave disabled unless mask_host expects it.
# mask_proxy_protocol = 0

# ------------------------------------------------------------------------------
# TLS Certificate Emulation
# ------------------------------------------------------------------------------

# Size (bytes) of the locally generated fake TLS certificate.
# Only used when tls_emulation is disabled.
fake_cert_len = 2048

# KILLER FEATURE: Real-Time TLS Emulation.
# Telemt connects to tls_domain, fetches its actual TLS 1.3 certificate chain,
# and exactly replicates the byte sizes of ServerHello and Certificate records.
# Defeats DPI that uses TLS record length heuristics to detect proxies.
# Strongly recommended in censored environments.
tls_emulation = true

# Directory to cache fetched TLS certificates.
tls_front_dir = "tlsfront"

# ------------------------------------------------------------------------------
# ServerHello Timing
# Real web servers take 30-150ms to respond to ClientHello due to network
# latency and crypto processing. A proxy responding in <1ms is suspicious.
# These settings add realistic delay to mimic genuine server behavior.
# ------------------------------------------------------------------------------

# Minimum delay before sending ServerHello (milliseconds).
server_hello_delay_min_ms = 50

# Maximum delay before sending ServerHello (milliseconds).
server_hello_delay_max_ms = 150

# ------------------------------------------------------------------------------
# TLS Session Tickets
# Real TLS 1.3 servers send 1-2 NewSessionTicket messages after handshake.
# A server that sends zero tickets is anomalous and may trigger DPI flags.
# Set this to match your tls_domain's behavior (usually 2).
# ------------------------------------------------------------------------------

# tls_new_session_tickets = 0

# ------------------------------------------------------------------------------
# Full Certificate Frequency
# When tls_emulation is enabled, this controls how often (per client IP)
# to send the complete emulated certificate chain.
#
# > 0: Subsequent connections within TTL seconds get a smaller cached version.
#       Saves bandwidth but creates a detectable size difference between
#       first and repeat connections.
#
# = 0: Every connection gets the full certificate. More bandwidth but
#       perfectly consistent behavior, no anomalies for DPI to detect.
# ------------------------------------------------------------------------------

tls_full_cert_ttl_secs = 0

# ------------------------------------------------------------------------------
# ALPN Enforcement
# Ensure ServerHello responds with the exact ALPN protocol the client requested.
# Mismatched ALPN (e.g., client asks h2, server says http/1.1) is a DPI red flag.
# ------------------------------------------------------------------------------

alpn_enforce = true


# ==============================================================================
# ACCESS CONTROL & USERS
# ==============================================================================

[access]

# ------------------------------------------------------------------------------
# Replay Attack Protection
# DPI can record a legitimate user's handshake and replay it later to probe
# whether the server is a proxy. Telemt remembers recent handshake nonces
# and rejects duplicates.
# ------------------------------------------------------------------------------

# Number of nonce slots in the replay detection buffer.
replay_check_len = 65536

# How long (seconds) to remember nonces before expiring them.
replay_window_secs = 1800

# Allow clients with incorrect system clocks to connect.
# false = reject clients with significant time skew (more secure)
# true  = accept anyone regardless of clock (more permissive)
ignore_time_skew = false

# ------------------------------------------------------------------------------
# User Secrets
# Each user needs a unique 32-character hex string as their secret.
# Generate with: openssl rand -hex 16
#
# This secret is embedded in the tg:// link. Anyone with it can connect.
# Format: username = "hex_secret"
# ------------------------------------------------------------------------------

[access.users]
# alice = "0123456789abcdef0123456789abcdef"
# bob = "fedcba9876543210fedcba9876543210"

# ------------------------------------------------------------------------------
# Per-User Connection Limits
# Limits concurrent TCP connections per user to prevent secret sharing.
# Uncomment and set for each user as needed.
# ------------------------------------------------------------------------------

[access.user_max_tcp_conns]
# alice = 100
# bob = 50

# ------------------------------------------------------------------------------
# Per-User Expiration Dates
# Automatically revoke access after the specified date (ISO 8601 format).
# ------------------------------------------------------------------------------

[access.user_expirations]
# alice = "2025-12-31T23:59:59Z"
# bob = "2026-06-15T00:00:00Z"

# ------------------------------------------------------------------------------
# Per-User Data Quotas
# Maximum total bytes transferred per user. Connection refused after limit.
# ------------------------------------------------------------------------------

[access.user_data_quota]
# alice = 107374182400
# bob = 53687091200

# ------------------------------------------------------------------------------
# Per-User Unique IP Limits
# Maximum number of different IP addresses that can use this secret
# at the same time. Highly effective against secret leaking/sharing.
# Set to 1 for single-device, 2-3 for phone+desktop, etc.
# ------------------------------------------------------------------------------

[access.user_max_unique_ips]
# alice = 3
# bob = 2


# ==============================================================================
# UPSTREAM ROUTING
# Controls how Telemt connects to Telegram servers (or ME servers).
# If omitted entirely, uses the OS default route.
# ==============================================================================

# ------------------------------------------------------------------------------
# Direct upstream: use the server's own network interface.
# You can optionally bind to a specific interface or local IP.
# ------------------------------------------------------------------------------

# [[upstreams]]
# type = "direct"
# interface = "eth0"
# bind_addresses = ["192.0.2.10"]
# weight = 1
# enabled = true
# scopes = "*"

# ------------------------------------------------------------------------------
# SOCKS5 upstream: route Telegram traffic through a SOCKS5 proxy.
# Useful if your server's IP is blocked from reaching Telegram DCs.
# ------------------------------------------------------------------------------

# [[upstreams]]
# type = "socks5"
# address = "198.51.100.30:1080"
# username = "proxy-user"
# password = "proxy-pass"
# weight = 1
# enabled = true


# ==============================================================================
# DATACENTER OVERRIDES
# Force specific DC IDs to route to specific IP:Port combinations.
# DC 203 (CDN) is auto-injected by Telemt if not specified here.
# ==============================================================================

# [dc_overrides]
# "201" = "149.154.175.50:443"
# "202" = ["149.154.167.51:443", "149.154.175.100:443"]