# Problem and Questions regarding client certificates

**URL:** <https://discourse.mitmproxy.org/t/problem-and-questions-regarding-client-certificates/1008>\
**Category:** help\
**Created:** [April 25, 2018, 2:23pm UTC](https://discourse.mitmproxy.org/t/problem-and-questions-regarding-client-certificates/1008 "2018-04-25T14:23:55Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![p1uymi](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@p1uymi](https://discourse.mitmproxy.org/u/p1uymi)\
**Post date:** [April 25, 2018, 2:23pm UTC](https://discourse.mitmproxy.org/t/problem-and-questions-regarding-client-certificates/1008/1 "2018-04-25T14:23:55Z")

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Hello,

I am new to mitmproxy and I have a couple of questions regarding client certificates. I made sure to google first/search to forum --\> didn’t find the right answers (If I missed them though pls link :)).

a) Is there a function that exports the on-the-fly generated certificates, if I want to use them, for example, in an addon?  
b) Are those on-the-fly generated certificates stored somewhere. (To inspect them at a later point)  
c) As I should be able to specify a directory for my client certificates, does mitmproxy load that directory once (in the beginning) or does mitmproxy load the directory/certificate when needed --\> implying it is possible to save a certificate into that folder while mitmproxy is already running, mitmproxy still will accept that new certificate?

To my problems: I can run _./mitmproxy --mode transparent_ without a problem, if I want to run _./mitmproxy --mode transparent --client-certs ~/mycertificates_ though i get the following error:

_mitmproxy: error: unrecognized arguments: --client-certs /home/p1uymi/mycertificates_

_–client-certs is deprecated._  
_Please use `--set client_certs=value` instead._

How am I able to fix this? do I use the commands wrong?

- I also had a look at [https://docs.mitmproxy.org/stable/concepts-certificates/](https://docs.mitmproxy.org/stable/concepts-certificates/) --\> didn’t solve my problems //// Also had a look at mitmproxy --options --\> Couldn’t figure out a solution.

With best regards,  
PM

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**Author:** ![p1uymi](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@p1uymi](https://discourse.mitmproxy.org/u/p1uymi)\
**Post date:** [April 26, 2018, 10:12am UTC](https://discourse.mitmproxy.org/t/problem-and-questions-regarding-client-certificates/1008/2 "2018-04-26T10:12:45Z")

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Update on my Problem: I solved it 😃

Apperently the _–clients-certs_ is the **v2** way, for **v3** i had to use _–set client\_certs=~/mycertificates_ in order to get it running.

That needs to be adapted in the Documentation for v3 🙂 ([https://docs.mitmproxy.org/stable/concepts-certificates/](https://docs.mitmproxy.org/stable/concepts-certificates/))

With bes regards,  
PM

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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 26, 2018, 1:38pm UTC](https://discourse.mitmproxy.org/t/problem-and-questions-regarding-client-certificates/1008/3 "2018-04-26T13:38:48Z")

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Ah, thanks! Would you mind submitting a PR that fixes this? 😃 There’s an “Edit on GitHub” button on the top right of each documentation page. 😊

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**Author:** ![p1uymi](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@p1uymi](https://discourse.mitmproxy.org/u/p1uymi)\
**Post date:** [April 26, 2018, 2:20pm UTC](https://discourse.mitmproxy.org/t/problem-and-questions-regarding-client-certificates/1008/4 "2018-04-26T14:20:55Z")

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Perfekt, created the PR.

As I wasn’t able to find any answer to my questions above yet, could you provide any? Especially if it is possible to modify the on-the-fly generated certificates (or at least inspect them at a later point) or not 🤔 Wasn’t able to find that out yet 😃

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**Author:** ![p1uymi](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@p1uymi](https://discourse.mitmproxy.org/u/p1uymi)\
**Post date:** [April 30, 2018, 12:46pm UTC](https://discourse.mitmproxy.org/t/problem-and-questions-regarding-client-certificates/1008/5 "2018-04-30T12:46:25Z")

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I solved my ‘c’ question, still haven’t found any answer to them, if anyone could give insight on those, i would be super happy.

_a) Is there a function that exports the on-the-fly generated certificates, if I want to use them, for example, in an addon?_  
_b) Are those on-the-fly generated certificates stored somewhere. (To inspect them at a later point)_

Cheers.