A tool that takes a list of domains from standard input (prefixed with the protocol or not), grabs the certificate and prints the CN and SANs.

It runs on 32 threads (goroutines) by default.

Running it against opendns-top-domains.txt (10000 domains) takes approximately 7 seconds:

$ time ./dumpcn -t=100 < opendns-top-domains.txt > /dev/null
./dumpcn -t=100 < opendns-top-domains.txt > /dev/null  1,66s user 1,24s system 39% cpu 7,311 total

$ go get -u github.com/samirettali/dumpcn

$ cat domains.txt | ./dumpcn

Change number of threads:

$ cat domains.txt | ./dumpcn -t=100