Yes, you can (where, as GrandmasterB points out, each peer has both server and client sockets). However, as you already know, NAT will cause you pain.
If you cannot use middlebox (servers at the public IP addresses that your clients connect to (*)), and you may not want them, because they are more likely to contradict the P2P point, and you are not using the mind describing the details of your connection to SDP , you can try Interactive Linking .
Essentially, ICE is trying to use different strategies for connecting. This is a plug-in architecture, so you can add your own strategies. By default, ICE describes UDP bypass methods, but an extension to allow a TCP connection.
(*) , IRC, - , , . P2P . ( SIP.)