50 lines
1.7 KiB
Python
50 lines
1.7 KiB
Python
"""
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This inline scripts makes it possible to use mitmproxy in scenarios where IP spoofing has been used to redirect
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connections to mitmproxy. The way this works is that we rely on either the TLS Server Name Indication (SNI) or the
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Host header of the HTTP request.
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Of course, this is not foolproof - if an HTTPS connection comes without SNI, we don't
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know the actual target and cannot construct a certificate that looks valid.
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Similarly, if there's no Host header or a spoofed Host header, we're out of luck as well.
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Using transparent mode is the better option most of the time.
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Usage:
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mitmproxy
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-p 443
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-s dns_spoofing.py
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# Used as the target location if neither SNI nor host header are present.
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-R http://example.com/
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mitmdump
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-p 80
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-R http://localhost:443/
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(Setting up a single proxy instance and using iptables to redirect to it
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works as well)
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"""
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import re
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# This regex extracts splits the host header into host and port.
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# Handles the edge case of IPv6 addresses containing colons.
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# https://bugzilla.mozilla.org/show_bug.cgi?id=45891
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parse_host_header = re.compile(r"^(?P<host>[^:]+|\[.+\])(?::(?P<port>\d+))?$")
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def request(flow):
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if flow.client_conn.ssl_established:
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flow.request.scheme = "https"
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sni = flow.client_conn.connection.get_servername()
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port = 443
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else:
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flow.request.scheme = "http"
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sni = None
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port = 80
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host_header = flow.request.pretty_host
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m = parse_host_header.match(host_header)
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if m:
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host_header = m.group("host").strip("[]")
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if m.group("port"):
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port = int(m.group("port"))
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flow.request.host = sni or host_header
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flow.request.port = port
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