Before configuring the reverse proxy, ensure you have:

• IIS 7 or later installed on Windows Server
• TeamCity running on Tomcat (default port 8111)
• Administrator privileges on the server
• URL Rewrite 2.0 and ARR 3.0 extensions installed

First, enable proxy functionality in Application Request Routing:

# Open IIS Manager
# Navigate to Server Node → Application Request Routing Cache
# Click "Server Proxy Settings" on right panel
# Check "Enable proxy" checkbox
# Apply changes

Add this web.config rule to your IIS site:

<configuration>
  <system.webServer>
    <rewrite>
      <rules>
        <rule name="ReverseProxy TeamCity" stopProcessing="true">
          <match url="^teamcity(.*)" />
          <action type="Rewrite" url="http://localhost:8111{R:1}" />
          <serverVariables>
            <set name="HTTP_X_FORWARDED_HOST" value="{HTTP_HOST}" />
            <set name="HTTP_X_FORWARDED_SCHEME" value="https" />
          </serverVariables>
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

For TeamCity's real-time features, add WebSocket support:

<webSocket enabled="false" />
<handlers>
  <add name="TeamCityWebSocket" 
       path="teamcity/app/subscriptions*" 
       verb="*" 
       modules="WebSocketModule" 
       resourceType="Unspecified" 
       requireAccess="Execute" />
</handlers>

1. 502 Bad Gateway: Verify TeamCity is running on the specified port and check firewall settings
2. CSS/JS not loading: Add URL rewrite outbound rules to fix resource paths
3. Authentication problems: Configure proxy-preserve-host header properly

For production environments, consider these ARR settings:

# In Server Proxy Settings:
- Connection timeout: 120 seconds
- Response buffer threshold: 0 (disable buffering)
- Enable disk cache
- Set cache size to 256MB

To enforce HTTPS:

<rule name="HTTP to HTTPS" enabled="true" stopProcessing="true">
  <match url="teamcity(.*)" />
  <conditions>
    <add input="{HTTPS}" pattern="off" />
  </conditions>
  <action type="Redirect" url="https://{HTTP_HOST}/teamcity{R:1}" />
</rule>

Before we begin, ensure you have the following installed:

• IIS 7 or later with Management Console
• TeamCity running on Tomcat (default port 8111)
• URL Rewrite Module 2.0 (download from Microsoft)
• Application Request Routing 3.0 (download from Microsoft)

First, we need to enable proxy functionality in Application Request Routing:

1. Open IIS Manager
2. Select the server node in the Connections pane
3. Double-click "Application Request Routing Cache"
4. Click "Server Proxy Settings" in the Actions pane
5. Check "Enable proxy"
6. Leave other settings as default
7. Click Apply

Now let's create the URL Rewrite rule for our TeamCity instance:

<rule name="ReverseProxyInboundRule1" enabled="true" stopProcessing="true">
    <match url="^teamcity(.*)" />
    <action type="Rewrite" url="http://localhost:8111/{R:1}" />
    <serverVariables>
        <set name="HTTP_X_FORWARDED_HOST" value="{HTTP_HOST}" />
        <set name="HTTP_X_FORWARDED_SCHEMA" value="https" />
    </serverVariables>
</rule>

We need to configure TeamCity to recognize the proxy headers:

1. Edit the <TeamCity>\conf\server.xml file
2. Add the following connector configuration:

<Connector port="8111" protocol="org.apache.coyote.http11.Http11NioProtocol"
    connectionTimeout="60000"
    useBodyEncodingForURI="true"
    socket.txBufSize="64000"
    socket.rxBufSize="64000"
    tcpNoDelay="1"
    scheme="https"
    proxyName="somesite"
    proxyPort="443"
    secure="true"/>

For TeamCity's WebSocket functionality to work through the proxy:

<rule name="TeamCity WebSocket" enabled="true">
    <match url="^teamcity/app/websocket(.*)" />
    <conditions>
        <add input="{HTTP_UPGRADE}" pattern="websocket" />
    </conditions>
    <action type="Rewrite" url="ws://localhost:8111/app/websocket{R:1}" />
</rule>

After applying all changes:

1. Restart both IIS and TeamCity services
2. Access https://somesite/teamcity in your browser
3. Verify all functionality including:
   • Main dashboard
   • Build logs
   • Real-time updates via WebSocket

If you encounter problems:

• 404 errors: Verify the rewrite rule pattern matches your URL structure
• Connection refused: Ensure TeamCity is running and listening on the correct port
• SSL issues: Make sure your IIS site has a valid SSL certificate
• WebSocket failures: Check that the WebSocket rule appears before the main proxy rule