# Couple observations

**URL:** <https://discourse.mitmproxy.org/t/couple-observations/965>\
**Category:** Uncategorized\
**Created:** [April 7, 2018, 3:48pm UTC](https://discourse.mitmproxy.org/t/couple-observations/965 "2018-04-07T15:48:58Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![DigiAngel](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DigiAngel](https://discourse.mitmproxy.org/u/DigiAngel)\
**Post date:** [April 7, 2018, 3:48pm UTC](https://discourse.mitmproxy.org/t/couple-observations/965/1 "2018-04-07T15:48:58Z")

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This is using 3.0.4.

1. Setting --listen-host -p 8889 seems to still use all interfaces: Proxy server listening at http://\*:8889

2. Using the \*=cert option and pointing it to the mitmproxy-ca.pem fails to work with untrusted in the browser, but leaving off the option and everything works well.

That’s it…thank you for a great app.

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**Author:** ![mhils](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mitmproxy.org/mhils/32/7_2.png) [@mhils](https://discourse.mitmproxy.org/u/mhils)\
**Post date:** [April 7, 2018, 5:26pm UTC](https://discourse.mitmproxy.org/t/couple-observations/965/2 "2018-04-07T17:26:10Z")

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Thanks for the feedback.

1. `listen_host` expects an argument.
2. Take a look at [https://docs.mitmproxy.org/stable/concepts-certificates/#using-a-custom-server-certificate](https://docs.mitmproxy.org/stable/concepts-certificates/#using-a-custom-server-certificate). `--cert` expects a leaf certificate, not a CA.

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**Author:** ![DigiAngel](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DigiAngel](https://discourse.mitmproxy.org/u/DigiAngel)\
**Post date:** [April 7, 2018, 6:52pm UTC](https://discourse.mitmproxy.org/t/couple-observations/965/3 "2018-04-07T18:52:37Z")

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Thank you…correction, I do have a host in the --listen-host -p 8889. And thank you I will look at the --cert option.

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**Author:** ![DigiAngel](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DigiAngel](https://discourse.mitmproxy.org/u/DigiAngel)\
**Post date:** [April 7, 2018, 6:53pm UTC](https://discourse.mitmproxy.org/t/couple-observations/965/4 "2018-04-07T18:53:41Z")

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LOL…looks like the forum is reformatting my posts 😉 my command is --listen-host IP -p 8889.