SSH Config to /etc/hosts Converter

What does the SSH Config to /etc/hosts Converter do?

The SSH Config to /etc/hosts Converter parses OpenSSH client configuration files (~/.ssh/config) and extracts Host aliases and HostName destinations (IP addresses or domains). It generates structured, fixed-width mapped lines ready to append directly into /etc/hosts (Linux/macOS) or C:\Windows\System32\drivers\etc\hosts (Windows).

Core Concepts

Understanding SSH config to /etc/hosts mapping:

• Host & HostName Pairing: Maps each target IP address from HostName to all declared Host alias nicknames on the same line.
• Multiple Alias Support: Automatically extracts multi-alias declarations (e.g. Host db db.internal db.local) into a single consolidated line.
• Column Padding: Formats output with 20-character column spacing for clean visual alignment in system network hosts files.

How to use the tool?

1. Paste SSH Config: Paste your ~/.ssh/config file content into the editor or click Load Sample Config.
2. Execute Conversion: Click Convert to /etc/hosts Format to extract host mapping entries.
3. Copy & Apply: Click Copy or Download, then append the output to /etc/hosts or your system hosts file.

Related Developer Utilities

If you work with SSH configurations, networking, and server provisioning, explore these complementary tools:

• SSH Config to Ansible Inventory Converter: Convert ~/.ssh/config to Ansible INI/YAML inventories.
• SSH Public Key Fingerprint Generator: Calculate SHA256 & MD5 SSH key fingerprints.
• SSH Public Key Format Converter: Convert keys between OpenSSH, RFC 4716, and PEM formats.
• YAML to JSON Converter: Convert structured YAML documents into clean JSON.

REST API Integration

Blueutils provides a free REST API endpoint (POST https://blueutils.com/api/ssh/ssh-config-to-hosts) to programmatically convert OpenSSH client configuration (~/.ssh/config) files into /etc/hosts mapping definitions.

API Request Parameters

API Request Payload Examples

cURL

curl -X POST https://blueutils.com/api/ssh/ssh-config-to-hosts \
  -H "Content-Type: application/json" \
  -d '{
    "rawText": "Host prod-db\n  HostName 10.0.1.50\n  User ubuntu\n\nHost web-staging\n  HostName 192.168.1.100"
  }'

Python

import requests

url = "https://blueutils.com/api/ssh/ssh-config-to-hosts"
payload = {
    "rawText": "Host prod-db\n  HostName 10.0.1.50\n  User ubuntu\n\nHost web-staging\n  HostName 192.168.1.100"
}
headers = {"Content-Type": "application/json"}
response = requests.post(url, json=payload, headers=headers)
print(response.json())

Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws Exception {
        String jsonPayload = """
            {
                "rawText": "Host prod-db\\n  HostName 10.0.1.50\\n  User ubuntu\\n\\nHost web-staging\\n  HostName 192.168.1.100"
            }
            """;

        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://blueutils.com/api/ssh/ssh-config-to-hosts"))
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(jsonPayload))
            .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.body());
    }
}

API Response Parameters

API Response Payload Examples

Success Response (HTTP 200 OK)

{
  "isValid": true,
  "convertedCount": 2,
  "converted": "# Generated from ~/.ssh/config via Blueutils\n# Format: <IP_OR_TARGET> <HOST_ALIAS>\n10.0.1.50            prod-db\n192.168.1.100        web-staging"
}

Validation Failure Response (HTTP 400 Bad Request)

{
  "isValid": false,
  "error": "No valid Host blocks with a \"HostName\" directive were found in the SSH config."
}

Rate Limit Exceeded Response (HTTP 429 Too Many Requests)

{
  "error": "API rate limit exceeded. Please wait or contact support@blueutils.com."
}

Why use an API to convert SSH config to /etc/hosts?

Integrating the SSH Config to /etc/hosts API into DevOps provisioning scripts, devcontainers, or AI agent tool calling provides key benefits:

• Rapid Script Validation: Generates local DNS aliases for ephemeral VM clusters and dev containers automatically.
• Optimized Token Efficiency for AI Agents: LLMs frequently mix up multi-alias column alignment. Calling the API extracts IP-hostname pairs deterministically without token consumption.
• Deterministic Accuracy Without Hallucinations: Ensures 100% accurate column alignment and syntax formatting for system network configuration.

Native Usage

How to convert SSH configs to /etc/hosts locally in terminal environments or scripts:

Windows (CMD / PowerShell)

# Extract Host and HostName from ~/.ssh/config in PowerShell
$configPath = "$env:USERPROFILE\.ssh\config"
if (Test-Path $configPath) {
    Get-Content $configPath | ForEach-Object {
        if ($_ -match '^\s*Host\s+([^\*]+)$') { $h = $matches[1].Trim() }
        elseif ($_ -match '^\s*HostName\s+(\S+)' -and $h) {
            Write-Output "$($matches[1].Trim().PadRight(20)) $h"
            $h = ""
        }
    }
}

Linux / Unix (Bash)

# Parse ~/.ssh/config using awk in Linux
awk '
  tolower($1) == "host" && $2 != "*" { host = $2 }
  tolower($1) == "hostname" && host != "" {
    printf "%-20s %s\n", $2, host
    host = ""
  }
' ~/.ssh/config

Python

Using Python:

import re

with open("~/.ssh/config".replace("~", "/home/user")) as f:
    content = f.read()

for match in re.finditer(r'Host\s+([^\n]+)\n\s+HostName\s+([^\n]+)', content):
    aliases = match.group(1).strip()
    ip = match.group(2).strip()
    print(f"{ip:<20} {aliases}")

Java

Using Java:

import java.nio.file.*;
import java.util.List;

public class SshToHostsExample {
    public static void main(String[] args) throws Exception {
        List<String> lines = Files.readAllLines(Paths.get(System.getProperty("user.home"), ".ssh", "config"));
        String host = "";
        for (String line : lines) {
            String trimmed = line.trim();
            if (trimmed.startsWith("Host ") && !trimmed.contains("*")) {
                host = trimmed.substring(5).trim();
            } else if (trimmed.startsWith("HostName ") && !host.isEmpty()) {
                String ip = trimmed.substring(9).trim();
                System.out.printf("%-20s %s%n", ip, host);
                host = "";
            }
        }
    }
}