There are a couple of reasons why you may want to exempt some traffic from mitmproxy's interception mechanism:

- **Certificate pinning:** Some traffic is is protected using
  [certificate pinning](https://security.stackexchange.com/questions/29988/what-is-certificate-pinning) and mitmproxy's
  interception leads to errors. For example, Windows Update or the Apple App Store fail to work if mitmproxy is active.
- **Non-HTTP traffic:** WebSockets or other non-http protocols are not supported by mitmproxy yet. You can exempt the
  domain from processing, which would otherwise fail.
- **Convenience:** You really don't care about some parts of the traffic and just want them to go away.

If you want to ignore traffic from mitmproxy's processing because of large response bodies, check out the
[response streaming](@!urlTo("responsestreaming.html")!@) feature.

## How it works


<table class="table">
    <tbody>
        <tr>
            <th width="20%">command-line</th> <td>--ignore regex</td>
        </tr>
        <tr>
            <th>mitmproxy shortcut</th> <td><b>I</b></td>
        </tr>
    </tbody>
</table>


mitmproxy allows you to specify a regex which is matched against a <code>host:port</code> string (e.g. "example.com:443")
to determine hosts that should be excluded. 

There are two important quirks to consider:

- **In transparent mode, the ignore pattern is matched against the IP.** While we usually infer the hostname from the 
  Host header if the --host argument is passed to mitmproxy, we do not have access to this information before the SSL
  handshake.
- In regular mode, explicit HTTP requests are never ignored.[^explicithttp] The ignore pattern is applied on CONNECT
  requests, which initiate HTTPS or clear-text WebSocket connections.


### Tutorial

If you just want to ignore one specific domain, there's usually a bulletproof method to do so:

1. Run mitmproxy or mitmdump in verbose mode (-v) and observe the host:port information in the serverconnect 
messages. mitmproxy will filter on these.
2. Take the host:port string, surround it with ^ and $, escape all dots (. becomes \\.) 
and use this as your ignore pattern:

<pre class="terminal">
$ mitmdump -v
127.0.0.1:50588: clientconnect
127.0.0.1:50588: request
  -> CONNECT example.com:443 HTTP/1.1
127.0.0.1:50588: Set new server address: example.com:443
<span style="color: white">127.0.0.1:50588: serverconnect
  -> example.com:443</span>
^C
$ <span style="color: white">mitmproxy --ignore ^example\.com:443$</span>    
</pre>

Here are some other examples for ignore patterns:
<pre>
# Exempt traffic from the iOS App Store (usually just works):
--ignore apple.com:443  
# "Correct" version without false-positives:
--ignore ^(.+\.)?apple\.com:443$ 
    
# Ignore example.com on all ports, but no subdomains:
--ignore ^example.com:
    
# Transparent mode:
--ignore 17\.178\.96\.59:443
# IP address range:
--ignore 17\.178\.\d+\.\d+:443
</pre>

[^explicithttp]: This stems from an limitation of explicit HTTP proxying: A single connection can be re-used for multiple target domains - a <code>GET http://example.com/</code> request may be followed by a <code>GET http://evil.com/</code> request on the same connection. If we start to ignore the connection after the first request, we would miss the relevant second one.