问题
For example, running wget https://www.dropbox.com results in the following errors:
ERROR: The certificate of `www.dropbox.com' is not trusted.
ERROR: The certificate of `www.dropbox.com' hasn't got a known issuer.
回答1:
Looking at current hacky solutions in here, I feel I have to describe a proper solution after all.
First, you need to install the cygwin package ca-certificates via Cygwin's setup.exe to get the certificates.
Do NOT use curl or similar hacks to download certificates (as a neighboring answer advices) because that's fundamentally insecure and may compromise the system.
Second, you need to tell wget where your certificates are, since it doesn't pick them up by default in Cygwin environment. If you can do that either with the command-line parameter --ca-directory=/usr/ssl/certs (best for shell scripts) or by adding ca_directory = /usr/ssl/certs to ~/.wgetrc file.
You can also fix that by running ln -sT /usr/ssl /etc/ssl as pointed out in another answer, but that will work only if you have administrative access to the system. Other solutions I described do not require that.
回答2:
If you don't care about checking the validity of the certificate just add the --no-check-certificate option on the wget command-line. This worked well for me.
NOTE: This opens you up to man-in-the-middle (MitM) attacks, and is not recommended for anything where you care about security.
回答3:
If the problem is that a known root CA is missing and when you are using ubuntu or debian, then you can solve the problem with this one line:
sudo apt-get install ca-certificates
回答4:
First, the SSL certificates need to be installed. Instructions (based on https://stackoverflow.com/a/4454754/278488):
pushd /usr/ssl/certs
curl http://curl.haxx.se/ca/cacert.pem | awk 'split_after==1{n++;split_after=0} /-----END CERTIFICATE-----/ {split_after=1} {print > "cert" n ".pem"}'
c_rehash
The above is enough to fix curl, but wget requires an extra symlink:
ln -sT /usr/ssl /etc/ssl
回答5:
May be this will help:
wget --no-check-certificate https://blah-blah.tld/path/filename
回答6:
apt-get install ca-certificates
The s makes the difference ;)
回答7:
I have the similar problem and fixed it by temporarily disabling my antivirus(Kaspersky Free 18.0.0.405). This AV has HTTPS interception module that automatically self-sign all certificates it finds in HTTPS responses.
Wget from Cygwin does not know anything about AV root certificate, so when it finds that website's certificate was signed with non trust certificate it prints that error.
To fix this permanently without disabling AV you should copy the AV root certificate from Windows certificate store to /etc/pki/ca-trust/source/anchors as .pem file(base64 encoding) and run update-ca-trust
回答8:
Just do
apt-get install ca-certificate
回答9:
If you are using windows just go to control panel, click on automatic updates then click on Windows Update Web Site link. Just follow the step. At least this works for me, no more certificates issue i.e whenever I go to https://www.dropbox.com as before.
来源：https://stackoverflow.com/questions/9224298/how-do-i-fix-certificate-errors-when-running-wget-on-an-https-url-in-cygwin