In my case I wanted to install subclipse, the eclipse market place is trying to connect to but resulting in to certificate error due to bad domain name. True it could be some fake sites pretending to be the trusted. But in this case, i know that this is this exact site.

“ PKIX path building failed: unable to find valid certification path to requested target”

Solution is to :

Download this certificate (I did it using chrome -> export functionality)

Add the certificate to cacerts (server trust store for java)

keytool -import -noprompt -trustcacerts -alias proxy_certficate -file /tmp/CertificateToBeTrusted  -keystore /etc/pki/ca-trust/extracted/java/cacerts -storepass changeit