Script that generates a bitcoin.conf Bitcoin Core Configuration file to be able to connect to multiple bitcoin core nodes.
Please use with moderation, you don't really want to run many clients that open connections to all the peers in the network for an extended amount of time, this will degrade the overall network perfomance. See this SO message from @pwuille: https://bitcoin.stackexchange.com/a/8140/12796
ruby bitnodes.rb
Then copy the config generated in bitnodes.txt into your bitcoin.conf. Edit the script to use sample() instead of sort() if you just want to add some random nodes and not all of them.
IP sources from blockchain.info
Check how many open connections you have:
bitcoin-cli getinfo | grep connections
Check how many different peers you are connected to:
bitcoin-cli getpeerinfo | grep subver | sort | uniq -c | sort -r