# portspoof-py

A Python asyncio rewrite of [portspoof](https://github.com/drk1wi/portspoof) — a TCP honeypot that makes every port on a machine appear open and running a real service.

When a port scanner connects to any TCP port, it receives a plausible fake service banner (SSH, HTTP, FTP, etc.). The banners are randomised from a signature library at startup, so the scanner cannot fingerprint the deception from banner patterns alone.

---

## Table of contents

1. [How it works](#how-it-works)
2. [Requirements](#requirements)
3. [Installation](#installation)
4. [Quick start](#quick-start)
5. [CLI reference](#cli-reference)
6. [Signature file](#signature-file)
7. [Config file](#config-file)
8. [iptables rules](#iptables-rules)
9. [JSON log](#json-log)
10. [Web admin interface](#web-admin-interface)
11. [Email alerts](#email-alerts)
12. [systemd service](#systemd-service)
13. [Recipes](#recipes)
14. [Troubleshooting](#troubleshooting)

---

## How it works

```
attacker                   kernel                    portspoof-py
   │                          │                           │
   │─── TCP SYN → port 443 ──►│                           │
   │                          │  iptables REDIRECT        │
   │                          │──► port 4444 ────────────►│
   │◄── TCP SYN-ACK ──────────│◄──────────────────────────│
   │─── data ────────────────►│──────────────────────────►│
   │                          │    SO_ORIGINAL_DST        │
   │                          │    recovers port 443      │
   │◄── fake HTTPS banner ────│◄──────────────────────────│
   │─── FIN ─────────────────►│──────────────────────────►│
```

1. **iptables PREROUTING REDIRECT** — on startup, three rules are added to the `nat` table. All incoming TCP traffic (except port 22 and the listener port itself) is transparently redirected to the single listener port.
2. **Single asyncio listener** — one coroutine handles every connection. There is no thread pool and no polling loop.
3. **SO_ORIGINAL_DST** — the Linux kernel preserves the originally-intended destination port in the socket. The handler reads it with `getsockopt(SOL_IP, SO_ORIGINAL_DST)`.
4. **Pre-computed banner map** — at startup, each of the 65,536 ports is assigned a banner generated by processing a randomly-chosen regex pattern from the signature file. Banner generation is done once; serving is instant.
5. **Graceful shutdown** — SIGTERM/SIGINT triggers the stop event, the server drains, the log queue is flushed, and the iptables rules are removed.

---

## Requirements

| Requirement | Notes |
|---|---|
| Python 3.11+ | Uses `asyncio`, `struct`, `socket`, `pathlib`, stdlib only |
| Linux | `SO_ORIGINAL_DST` and `iptables` are Linux-specific |
| Root | Required for iptables management; `--no-iptables` bypasses this |
| iptables | Must be installed (`apt install iptables` or equivalent) |

No PyPI packages are needed at runtime.

---

## Installation

**Run directly from the source tree (recommended for a lab machine):**

```bash
git clone <repo>
cd portspoof_py
sudo python3 -m portspoof_py -s tools/portspoof_signatures
```

**Install as a package:**

```bash
pip install .          # installs the portspoof-py entry point
portspoof-py --help
```

**Install build tool only if needed:**

```bash
pip install flit
flit build             # produces a wheel in dist/
```

---

## Quick start

### Test mode (no iptables, no root)

Useful for verifying the installation or developing.

```bash
python3 -m portspoof_py \
    --no-iptables \
    -p 4444 \
    -s tools/portspoof_signatures \
    -v

# In another terminal — should receive a random service banner
nc localhost 4444
```

### Full honeypot mode (as root)

```bash
sudo python3 -m portspoof_py \
    -p 4444 \
    -s /etc/portspoof/portspoof_signatures \
    -c /etc/portspoof/portspoof.conf \
    -l /var/log/portspoof/portspoof.jsonl
```

After startup you can verify with:

```bash
sudo iptables -t nat -L PREROUTING --line-numbers
# Should show three portspoof rules

nmap -p 1-1000 <your-ip>
# All ports should appear open
```

Stop with Ctrl-C or `kill <pid>`. Rules are removed automatically.

### With the web admin interface

```bash
# Create a credentials file first
echo "admin:changeme" > admin.passwd

sudo python3 -m portspoof_py \
    -p 4444 \
    -s /etc/portspoof/portspoof_signatures \
    -l /var/log/portspoof/portspoof.jsonl \
    --admin-port 8080

# Open http://127.0.0.1:8080 in a browser (HTTP Basic Auth prompt will appear)
```

---

## CLI reference

```
python3 -m portspoof_py [OPTIONS]
portspoof-py [OPTIONS]
```

### Listener

| Flag | Default | Description |
|---|---|---|
| `-p PORT` / `--port PORT` | `4444` | TCP port the honeypot listens on. This port is excluded from the iptables REDIRECT rule so it does not redirect to itself. |
| `-i IP` / `--bind-ip IP` | all interfaces | Bind the listener to a specific IP address. |

### Signatures and configuration

| Flag | Default | Description |
|---|---|---|
| `-s FILE` / `--signatures FILE` | — | Path to the signature file. Each line is a regex-like pattern used to generate a banner. At startup, one pattern is chosen randomly for each of the 65,536 ports. Without this flag every port returns an empty banner (the port appears open but silent). |
| `-c FILE` / `--config FILE` | — | Path to the config file. Overrides specific ports or port ranges with a fixed payload after the signature map is built. |

### Logging

| Flag | Default | Description |
|---|---|---|
| `-l FILE` / `--log-file FILE` | — | Append JSON connection events to this file. One line per connection. |
| `-v` / `--verbose` | off | Print each connection event as JSON to stdout. |

### iptables

| Flag | Default | Description |
|---|---|---|
| `--iface IFACE` | all interfaces | Restrict the iptables REDIRECT rule to a specific network interface (e.g. `eth0`). Useful when one interface is internal and should not be intercepted. |
| `--no-iptables` | off | Skip iptables setup and teardown entirely. The listener still runs on `-p PORT`. Use for local testing or when you manage iptables externally. |

### Web admin

| Flag | Default | Description |
|---|---|---|
| `--admin-port PORT` | disabled | Start the web admin interface on this port. |
| `--admin-host HOST` | `127.0.0.1` | Address the admin interface binds to. Set to `0.0.0.0` to expose it on all interfaces (protect with a firewall). |
| `--admin-passwd FILE` | `admin.passwd` | File containing `username:password` on a single line. Required when `--admin-port` is used. |
| `--admin-ssl` | off | Serve the admin interface over HTTPS. |
| `--admin-ssl-cert FILE` | `admin.crt` | TLS certificate PEM file. If the file does not exist it is auto-generated as a self-signed cert (requires `openssl` on PATH). |
| `--admin-ssl-key FILE` | `admin.key` | TLS private key PEM file. Auto-generated alongside the cert if missing. |
| `--email-config FILE` | `email.json` | JSON file where email alert settings are stored. Created automatically when you first save settings from the admin UI. |

---

## Signature file

The signature file contains one pattern per line. Blank lines are ignored. The bundled file `tools/portspoof_signatures` contains 8,962 patterns derived from the nmap service detection database.

Each pattern is passed through a three-pass regex materialiser at startup to produce a concrete banner string:

**Pass 1** — group and bracket expansion
- `(...)` groups are stripped, their content kept.
- `[abc]`, `[a-z]`, `[0-9]`, `[^\0]` etc. are expanded: a random character (or random-length sequence for `*`/`+` quantifiers) is chosen from the defined set.

**Pass 2** — special sequence substitution
- `\w` → a random lowercase letter `a`–`z`
- `\d` → a random digit `0`–`9`
- `.` → a random lowercase letter
- `\n`, `\r`, `\t` → literal newline, carriage return, tab

**Pass 3** — hex escape decoding
- `\xNN` → the byte with hex value `NN`

**Example patterns and what they can produce:**

```
# Input pattern                         → Example output
SSH-2.0-OpenSSH_([\w._-]+)\r\n         → SSH-2g0-OpenSSH_QpKz\r\n
220 ([-.\w]+) ESMTP\r\n                → 220 mxprod ESMTP\r\n
HTTP/1.\d \d\d\d [\w ]+\r\n            → HTTP/1.4 200 OK\r\n
\x80\x01\x00\x80                       → (four literal bytes)
AMServer                               → AMServer
```

The file is read with latin-1 encoding so binary-like content in patterns does not cause decode errors.

---

## Config file

The config file lets you pin specific ports or port ranges to a fixed payload, overriding the random assignment from the signature file. It is applied after the signature map is built.

### Format

Lines beginning with `#` are comments and are ignored. Each active line has the form:

```
PORT "payload"
START-END "payload"
```

The payload is everything between the **first** and **last** double-quote on the line. It is processed through the same three-pass materialiser as signature patterns, so hex escapes and regex metacharacters work.

### Example

```
# Single port — port 22 returns a specific SSH banner
22 "SSH-2.0-OpenSSH_8.9p1 Ubuntu-3ubuntu0.6\r\n"

# Port range — ports 80 through 443 return an HTTP 200
80-443 "HTTP/1.1 200 OK\r\nServer: nginx/1.24.0\r\nContent-Length: 0\r\n\r\n"

# Hex payload — raw bytes
9200 "\x7b\x22\x6e\x61\x6d\x65\x22\x3a\x22\x65\x6c\x61\x73\x74\x69\x63\x22\x7d"
```

The bundled `tools/portspoof.conf` shows the full comment syntax and more examples.

---

## iptables rules

When running without `--no-iptables`, three rules are appended to the `nat` PREROUTING chain at startup and removed at shutdown.

### Rules added (example with `-p 4444 --admin-port 8080`)

```
iptables -t nat -A PREROUTING -p tcp --dport 22   -j RETURN
iptables -t nat -A PREROUTING -p tcp --dport 8080 -j RETURN
iptables -t nat -A PREROUTING -p tcp --dport 4444 -j RETURN
iptables -t nat -A PREROUTING -p tcp              -j REDIRECT --to-port 4444
```

The exempt ports are always added **before** the REDIRECT rule in this order:

1. Port 22 (SSH) — always first, so you cannot lock yourself out.
2. `--admin-port` — exempted automatically if specified, so the admin interface remains reachable.
3. The listener port (`-p`) — prevents a redirect loop.

Without `--admin-port`, the middle rule is omitted.

With `--iface eth0`, each rule gains `--in-interface eth0`.

### Verifying the rules

```bash
sudo iptables -t nat -L PREROUTING -v --line-numbers
```

### Manual cleanup

If the process is killed with SIGKILL (skipping the shutdown handler), the systemd `ExecStopPost` directives remove the rules. You can also remove them manually:

```bash
sudo iptables -t nat -D PREROUTING -p tcp --dport 22   -j RETURN
sudo iptables -t nat -D PREROUTING -p tcp --dport 4444 -j RETURN
sudo iptables -t nat -D PREROUTING -p tcp              -j REDIRECT --to-port 4444
```

### Persistence across reboots

iptables rules are not persistent by default. The systemd service re-adds them on start. If you want them to survive without the service running, use `iptables-save` / `iptables-restore` or `netfilter-persistent`.

---

## JSON log

With `-l FILE`, each accepted connection appends one JSON object followed by a newline to the log file.

### Fields

| Field | Type | Description |
|---|---|---|
| `timestamp` | string | ISO 8601 UTC timestamp with microseconds |
| `src_ip` | string | Source IP address of the scanner |
| `src_port` | integer | Source (ephemeral) port of the scanner |
| `dst_port` | integer | Port the scanner originally connected to (recovered via `SO_ORIGINAL_DST`) |
| `banner_hex` | string | Hex-encoded bytes of the banner that was sent |
| `banner_len` | integer | Length of the banner in bytes |

### Example

```json
{"timestamp": "2025-06-01T14:32:07.841203+00:00", "src_ip": "198.51.100.42", "src_port": 54312, "dst_port": 443, "banner_hex": "485454502f312e31203230300d0a", "banner_len": 14}
```

### Querying the log

```bash
# Show all source IPs sorted by frequency
jq -r .src_ip portspoof.jsonl | sort | uniq -c | sort -rn | head -20

# Show all targeted ports sorted by frequency
jq -r .dst_port portspoof.jsonl | sort | uniq -c | sort -rn | head -20

# Show connections from a specific IP
jq 'select(.src_ip == "198.51.100.42")' portspoof.jsonl

# Decode a banner from hex
jq -r .banner_hex portspoof.jsonl | head -1 | xxd -r -p
```

---

## Web admin interface

Enable with `--admin-port PORT`. The interface binds to `127.0.0.1` by default; use `--admin-host 0.0.0.0` to expose it externally (ensure it is firewalled).

### Authentication

Every request requires HTTP Basic Auth. Create a credentials file before starting:

```bash
echo "admin:changeme" > admin.passwd
```

The file must contain a single line in `username:password` format. Pass a custom path with `--admin-passwd FILE`.

### HTTPS / TLS

Add `--admin-ssl` to serve the interface over HTTPS:

```bash
sudo python3 -m portspoof_py \
    -p 4444 -s tools/portspoof_signatures \
    --admin-port 8080 --admin-ssl
```

On first run, a self-signed certificate (`admin.crt` / `admin.key`) is generated automatically using `openssl`. Your browser will show an untrusted-certificate warning — add an exception or use a real cert.

To use your own certificate:

```bash
--admin-ssl --admin-ssl-cert /etc/ssl/mycert.pem --admin-ssl-key /etc/ssl/mykey.pem
```

### Dashboard — `GET /`

A dark-themed HTML page that auto-refreshes every 5 seconds. Sections:

- **Stat cards** — total connections, connections in the last 60 seconds, uptime, ports mapped, and last connection time.
- **Top source IPs** — the 10 most active scanner addresses since startup.
- **Top targeted ports** — the 10 most-probed ports since startup.
- **Banner lookup** — enter any port number (0–65535) and see the hex and text preview of the banner that port will send. The result persists across auto-refreshes when using the `?port=N` query parameter.
- **Recent connections** — the 50 most-recent connections, newest first, with timestamp, source, destination port, banner hex excerpt, and banner length.

### Banner lookup shortcut

Append `?port=N` to the dashboard URL to pre-populate the lookup:

```
http://127.0.0.1:8080/?port=443
```

### JSON API

All endpoints require Basic Auth and return `Content-Type: application/json`.

#### `GET /api/stats`

Current statistics snapshot.

```json
{
  "uptime": "2h 14m 37s",
  "total_connections": 18432,
  "last_connection": "2025-06-01T14:32:07.841203+00:00",
  "connections_per_min": 312,
  "ports_mapped": 65536,
  "top_ips": [
    {"ip": "198.51.100.42", "count": 9821},
    {"ip": "203.0.113.7",   "count": 4102}
  ],
  "top_ports": [
    {"port": 80,   "count": 3201},
    {"port": 443,  "count": 2987},
    {"port": 22,   "count": 2104}
  ]
}
```

#### `GET /api/connections?limit=N`

The N most-recent connection events, newest first. `limit` defaults to 50, maximum 500.

```json
[
  {
    "timestamp": "2025-06-01T14:32:07.841203+00:00",
    "src_ip":    "198.51.100.42",
    "src_port":  54312,
    "dst_port":  443,
    "banner_hex": "485454502f312e31203230300d0a",
    "banner_len": 14
  }
]
```

#### `GET /api/banner?port=N`

The pre-computed banner for port N.

```json
{
  "port":        443,
  "banner_hex":  "485454502f312e31203230300d0a",
  "banner_len":  14,
  "banner_text": "HTTP/1.1 200\r\n"
}
```

`banner_text` is the banner decoded as latin-1. Non-printable bytes will appear as replacement characters in some terminals.

#### `GET /api/email/config`

Current email alert configuration (password is masked).

---

## Email alerts

portspoof can send email digest alerts when connections are detected. Configuration is done entirely through the admin UI — no restart required.

### Setup

1. Start with `--admin-port` (the email config page is always available).
2. Open `http://127.0.0.1:8080/config` (or click **email alerts** in the dashboard header).
3. Fill in your SMTP details and click **Save**.
4. Click **Send test email** to verify delivery.

### How batching works

Rather than sending one email per connection, portspoof collects events and sends a single digest:

1. When a matching connection arrives, it is added to a pending list and a flush timer starts.
2. Any further matching connections within the **batch delay** window are added to the same list.
3. After the batch delay elapses, one email is sent summarising all collected events.
4. The **cooldown** prevents a new batch from being sent until that many seconds have passed since the last one, avoiding email floods during sustained scans.

### Configuration options

| Option | Default | Description |
|---|---|---|
| Enabled | off | Master switch — no emails are sent when disabled. |
| SMTP host | — | Hostname of your SMTP server (e.g. `smtp.gmail.com`). |
| SMTP port | `587` | Port to connect to. |
| Use STARTTLS | on | Upgrade the connection with STARTTLS. Disable for plain SMTP or SSL-only servers. |
| SMTP username | — | Login username for SMTP authentication. |
| SMTP password | — | Login password. Stored in the config file; masked in the UI. |
| From address | — | Sender address. Defaults to the SMTP username if blank. |
| To address | — | Recipient address for alert emails. |
| Trigger ports | (all) | Comma-separated list of ports that trigger alerts. Leave blank to alert on every port. |
| Batch delay | `60` s | How long to wait and collect events before sending one digest email. |
| Cooldown | `300` s | Minimum time between batch emails. |

### Config file

Settings are saved to `email.json` (or the path given by `--email-config`) as JSON. The file is created on first save. You can edit it directly; changes take effect at the next batch send.

```json
{
  "enabled": true,
  "smtp_host": "smtp.gmail.com",
  "smtp_port": 587,
  "smtp_starttls": true,
  "smtp_user": "you@gmail.com",
  "smtp_password": "app-password-here",
  "from_addr": "",
  "to_addr": "alerts@example.com",
  "trigger_ports": [22, 3389],
  "batch_delay_seconds": 60,
  "cooldown_seconds": 300
}
```

### Example digest email

```
Subject: [portspoof] 3 connections detected

portspoof alert — 3 connections

  2025-06-01 14:32:07  198.51.100.42:54312  →  port 22   (14 B  485353482d322e302d4f70656e5353…)
  2025-06-01 14:32:09  198.51.100.42:54398  →  port 23   (6 B   deadbeef0102)
  2025-06-01 14:32:11  203.0.113.7:61204    →  port 3389 (0 B   )
```

---

## systemd service

The included `portspoof.service` file runs portspoof as a system service that starts after the network is up, restarts on failure, and removes iptables rules even if it is killed with SIGKILL.

### Installation

```bash
# Copy files
sudo cp portspoof.service /etc/systemd/system/
sudo mkdir -p /etc/portspoof /var/log/portspoof
sudo cp tools/portspoof_signatures /etc/portspoof/
sudo cp tools/portspoof.conf       /etc/portspoof/

# Enable and start
sudo systemctl daemon-reload
sudo systemctl enable portspoof
sudo systemctl start portspoof

# Check status
sudo systemctl status portspoof
sudo journalctl -u portspoof -f
```

### Adding the admin interface to the service

```bash
# Create credentials file
echo "admin:changeme" | sudo tee /etc/portspoof/admin.passwd
sudo chmod 600 /etc/portspoof/admin.passwd
```

Edit `/etc/systemd/system/portspoof.service` and append the flags to `ExecStart`:

```ini
ExecStart=/usr/bin/python3 -m portspoof_py \
    -s /etc/portspoof/portspoof_signatures \
    -c /etc/portspoof/portspoof.conf \
    -l /var/log/portspoof/portspoof.jsonl \
    --admin-port 8080 \
    --admin-passwd /etc/portspoof/admin.passwd \
    --email-config /etc/portspoof/email.json
```

Then reload:

```bash
sudo systemctl daemon-reload
sudo systemctl restart portspoof
```

### Stopping

```bash
sudo systemctl stop portspoof
# iptables rules are removed during graceful shutdown
# ExecStopPost directives handle the SIGKILL case
```

---

## Recipes

### Honeypot on a dedicated interface only

```bash
sudo python3 -m portspoof_py \
    -p 4444 \
    --iface eth1 \
    -s /etc/portspoof/portspoof_signatures \
    -l /var/log/portspoof/portspoof.jsonl
```

Only traffic arriving on `eth1` is redirected. Traffic on other interfaces (e.g. a management interface) is unaffected.

### Monitor in real time with the admin API

```bash
# Poll stats every second
watch -n1 'curl -su admin:changeme http://127.0.0.1:8080/api/stats | python3 -m json.tool'

# Tail recent connections
watch -n2 'curl -su admin:changeme "http://127.0.0.1:8080/api/connections?limit=10" | python3 -m json.tool'
```

### Inspect what a specific port would send

```bash
curl -su admin:changeme "http://127.0.0.1:8080/api/banner?port=22" | python3 -m json.tool

# Decode banner bytes directly
curl -su admin:changeme "http://127.0.0.1:8080/api/banner?port=22" \
  | python3 -c "import sys,json; print(json.load(sys.stdin)['banner_text'])"
```

### Custom banners for a port range

Create `/etc/portspoof/portspoof.conf`:

```
# Make ports 8080-8090 look like nginx
8080-8090 "HTTP/1.1 200 OK\r\nServer: nginx/1.24.0\r\nContent-Length: 612\r\n\r\n"

# Make port 3306 look like MySQL
3306 "\x4a\x00\x00\x00\x0a\x38\x2e\x30\x2e\x33\x36\x00"
```

### Analyse a scan after the fact

```bash
# Top 10 IPs
jq -r .src_ip /var/log/portspoof/portspoof.jsonl \
  | sort | uniq -c | sort -rn | head -10

# All ports targeted in the last hour
jq -r 'select(.timestamp > "2025-06-01T13:00:00") | .dst_port' \
  /var/log/portspoof/portspoof.jsonl | sort -n | uniq -c | sort -rn | head -20

# Check if a specific IP hit you
grep '"src_ip": "198.51.100.42"' /var/log/portspoof/portspoof.jsonl | wc -l
```

---

## Troubleshooting

### `ERROR: root required for iptables management`

Run with `sudo`, or pass `--no-iptables` if you are testing locally.

### `ERROR: iptables setup failed`

Check that iptables is installed and the `nat` table is available:

```bash
sudo iptables -t nat -L
```

On some minimal systems you may need:

```bash
sudo apt install iptables        # Debian/Ubuntu
sudo modprobe ip_tables
sudo modprobe iptable_nat
```

### Banners contain `000` instead of null bytes

This is expected. The signature file uses `\0` to represent null bytes in the nmap probe format, but the banner materialiser does not interpret `\0` as a null byte — it outputs the ASCII character `0` (0x30). Use `\x00` in signature patterns or config payloads when you need an actual null byte.

### Port 22 is redirected and SSH breaks

The iptables setup adds a `RETURN` rule for port 22 before the `REDIRECT` rule, so SSH should always be exempt. If you are still locked out, verify the rule order:

```bash
sudo iptables -t nat -L PREROUTING --line-numbers
```

The `RETURN` rules for port 22 and the listener port must appear **before** the `REDIRECT` rule. If they are in the wrong order, remove all portspoof rules and restart the service.

### `SO_ORIGINAL_DST` returns the listener port instead of the original port

This happens when there is no `REDIRECT` rule in effect (e.g. `--no-iptables` mode, or the rule is missing). The server falls back to reporting the listener port as the destination. Banners are still sent; the logged `dst_port` will be the listener port rather than the port the scanner connected to.

### Admin interface is not accessible from a remote machine

By default `--admin-host` is `127.0.0.1` (localhost only). To expose it remotely:

```bash
--admin-host 0.0.0.0 --admin-port 8080
```

Then allow the port in your firewall and restrict access to trusted IPs:

```bash
sudo iptables -A INPUT -p tcp --dport 8080 -s <your-ip> -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 8080 -j DROP
```

### Startup is slow (~4–5 seconds)

The banner map is built synchronously at startup: 65,536 ports × one signature materialisation each. This is expected and is a one-time cost. After startup, every connection is served from the pre-computed map with no per-connection processing.