zlib source code failed to download in VPN (ZScaler)

[memsharded]

When running the training in the docker and enabled my VPN (ZSCaler), the download of the source code from sourceforge will fail.

This fails in Ex.16, when cross-building the zlib:

zlib/1.2.11: Configuring sources in /home/conan/.conan/data/zlib/1.2.11/_/_/source
ERROR: Error downloading file https://zlib.net/zlib-1.2.11.tar.gz: 'HTTPSConnectionPool(host='zlib.net', port=443): Max retries exceeded with url: /zlib-1.2.11.tar.gz (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1076)')))'

wget will fail too:

wget https://downloads.sourceforge.net/project/libpng/zlib/1.2.11/zlib-1.2.11.tar.gz
ERROR: cannot verify downloads.sourceforge.net's certificate, issued by 'CN=Zscaler Intermediate Root CA (zscaler.net) (t)\\ ,OU=Zscaler Inc.,O=Zscaler Inc.,ST=California,C=US':
  Unable to locally verify the issuer's authority.
To connect to downloads.sourceforge.net insecurely, use `--no-check-certificate'

I have checked without the VPN and it works. Other users worked for them, even if using ZScaler too.

[penugondac]

• Pl. add your Zscalar root certificates contents inside cacert.pem file present in ~/.conan directory.
• By adding the ZScalar root certificate in the above file the issue is resolved.

[solvingj]

Thank you so much for reporting this workaround. It seems likely it will help future users. How did you obtain your ZScalar root certificates btw?