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1 + # Protecting sshd with spiped
2 +
3 + This repository shows how to place **spiped** in front of your SSH daemon (`sshd`) in order to add an extra layer of symmetric-key protection and drastically reduce your exposed attack surface.
4 +
5 + ---
6 +
7 + ## What is spiped?
8 +
9 + `spiped` is a lightweight daemon designed to create symmetrically encrypted and authenticated “pipes” between socket addresses. It binds a local TCP port and forwards traffic to another socket—typically on the same machine—**while encrypting and verifying** all data in transit.
10 +
11 + It resembles the port-forwarding feature of SSH (`ssh -L`), but uses a pre-shared symmetric key rather than SSH’s full session model, making it simpler and more focused on **secure tunneling**.
12 +
13 + ---
14 +
15 + ## Why protect your SSH daemon with spiped?
16 +
17 + Running `sshd` behind a `spiped` tunnel adds a strong additional security layer that prevents nearly all unauthorized SSH access attempts before they even reach your server.
18 +
19 + Because `spiped` only accepts connections encrypted with a pre-shared key, any unauthenticated traffic is dropped immediately—long before it can trigger password guessing, exploit attempts, or even banner visibility.
20 +
21 + ### Key advantages
22 +
23 + - **Eliminates SSH port scanning & brute-force noise**
24 + Scanners and bots see nothing: your SSH port becomes completely inaccessible unless the client first establishes a valid `spiped` session.
25 +
26 + - **Adds symmetric-key access control before SSH**
27 + Only clients that already possess the shared `spiped` key can even *reach* `sshd`. SSH authentication remains in place, but protected by an extra security layer.
28 +
29 + - **Prevents protocol fingerprinting**
30 + Attackers cannot detect that SSH is running at all, reducing exposure to targeted SSH vulnerabilities.
31 +
32 + - **Simple, low-overhead protection**
33 + `spiped` uses fast symmetric cryptography and introduces minimal latency.
34 +
35 + - **Defense in depth**
36 + Attackers must bypass both the spiped key AND SSH authentication.
37 +
38 + ---
39 +
40 + ## How it works
41 +
42 + `spiped` runs as a secure encrypted conduit between a *source address* (a public port) and a *target address* (typically `127.0.0.1:22`). All traffic is encrypted, authenticated, and verified before reaching `sshd`.
43 +
44 + ### Flow:
45 +
46 + 1. **Client initiates a spiped session** using the shared key.
47 + 2. **Key exchange** occurs (Diffie-Hellman + HMAC-SHA256).
48 + 3. **Traffic is encrypted** with AES-256-CTR + HMAC-SHA256.
49 + 4. **Verified traffic** is forwarded to `sshd`.
50 + 5. SSH authentication happens normally afterward.
51 +
52 + ### ASCII Diagram
53 +
54 + ```text
55 + ┌────────────────────────────────────────┐
56 + │ CLIENT │
57 + │ │
58 + │ ssh → spiped (client-side) │
59 + └───────────────┬────────────────────────┘
60 + │
61 + │ Encrypted + Authenticated
62 + │ (AES-256-CTR + HMAC-SHA256)
63 + ▼
64 + ┌────────────────────┐
65 + │ NETWORK / WAN │
66 + └───────────┬────────┘
67 + │
68 + ▼
69 + ┌────────────────────────────────────────┐
70 + │ SERVER │
71 + │ │
72 + │ spiped (server-side) → sshd │
73 + │ │ decrypt + verify │ │
74 + │ └──────────────────────┘ │
75 + └────────────────────────────────────────┘
76 + ```
77 +
78 + ---
79 +
80 + ## Installation & setup (systemd)
81 +
82 + This example uses:
83 +
84 + - spiped listening on **0.0.0.0:8022**
85 + - sshd listening on **127.0.0.1:22**
86 + - key stored at **/etc/ssh/spiped-secret**
87 +
88 + ### 1. Generate the shared key
89 +
90 + ```bash
91 + sudo dd if=/dev/urandom bs=32 count=1 of=/etc/ssh/spiped-secret
92 + sudo chmod 600 /etc/ssh/spiped-secret
93 + sudo chown root:root /etc/ssh/spiped-secret
94 + ```
95 +
96 + ### 2. Create the systemd service
97 +
98 + Place this at: `/etc/systemd/system/spiped-ssh.service`
99 +
100 + ```ini
101 + [Unit]
102 + Description=Spiped for SSH
103 + After=network.target
104 +
105 + [Service]
106 + Type=simple
107 + ExecStart=/usr/bin/spiped -F -d -s '[0.0.0.0]:8022' -t '[127.0.0.1]:22' -k /etc/ssh/spiped-secret
108 + Restart=always
109 +
110 + [Install]
111 + WantedBy=multi-user.target
112 + ```
113 +
114 + Reload systemd:
115 +
116 + ```bash
117 + sudo systemctl daemon-reload
118 + ```
119 +
120 + ### 3. Enable at boot
121 +
122 + ```bash
123 + sudo systemctl enable spiped-ssh.service
124 + ```
125 +
126 + ### 4. Start the service
127 +
128 + ```bash
129 + sudo systemctl start spiped-ssh.service
130 + ```
131 +
132 + ### 5. Stop / restart / disable
133 +
134 + ```bash
135 + sudo systemctl stop spiped-ssh.service
136 + sudo systemctl restart spiped-ssh.service
137 + sudo systemctl disable spiped-ssh.service
138 + ```
139 +
140 + ---
141 +
142 + ## Connecting to a spiped-protected SSH server (client setup via ProxyCommand)
143 +
144 + You can configure SSH to automatically launch `spiped` using the `ProxyCommand` directive. SSH starts spiped when connecting, pipes traffic through it, and closes it afterward.
145 +
146 + ### 1. Install spiped on the client
147 +
148 + ```bash
149 + # Debian/Ubuntu
150 + sudo apt install spiped
151 +
152 + # Fedora/RHEL
153 + sudo dnf install spiped
154 +
155 + # macOS
156 + brew install spiped
157 + ```
158 +
159 + ### 2. Copy the shared key to the client
160 +
161 + Store it safely:
162 +
163 + ```
164 + ~/.config/spiped/ssh-secret
165 + ```
166 +
167 + Fix permissions:
168 +
169 + ```bash
170 + chmod 600 ~/.config/spiped/ssh-secret
171 + ```
172 +
173 + ### 3. Add SSH config entry
174 +
175 + Edit `~/.ssh/config`:
176 +
177 + ```
178 + Host my-spiped-server
179 + HostName 127.0.0.1
180 + User USERNAME
181 + Port 22
182 + ProxyCommand spiped -e -t '[SERVER_PUBLIC_IP]:8022' -k ~/.config/spiped/ssh-secret -F -o 2>/dev/null
183 + ```
184 +
185 + ### What this does
186 +
187 + - SSH launches spiped automatically.
188 + - spiped connects to the server’s encrypted spiped listener.
189 + - SSH traffic flows through the secure tunnel.
190 + - spiped terminates when the SSH session closes.
191 +
192 + ### 4. Connect normally
193 +
194 + ```bash
195 + ssh my-spiped-server
196 + ```
197 +
198 + ### Optional: shorter alias
199 +
200 + ```
201 + Host prod
202 + HostName 127.0.0.1
203 + User USERNAME
204 + ProxyCommand spiped -e -t '[SERVER_PUBLIC_IP]:8022' -k ~/.config/spiped/ssh-secret -F -o 2>/dev/null
205 + ```
206 +
207 + Then:
208 +
209 + ```bash
210 + ssh prod
211 + ```
212 +
213 + ---
214 +
215 + With this setup, your SSH daemon is fully shielded behind spiped, dramatically reducing exposure while preserving your normal SSH workflow.
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