This is related to Bug 364129. With media-gfx/iscan-network-nt-1.1.1.1 (epkowa network setup) scanimage hangs if kernel has no SYN cookies support compiled in (CONFIG_SYN_COOKIES). Symptoms: TCP: request_sock_TCP: Possible SYN flooding on port 38845. Dropping request. See also https://bugs.launchpad.net/ubuntu/+source/procps/+bug/57091/comments/27. I suggest to add a pre-install check or to drop a post-install message warning of the problem.
If that package is the one requiring this I would move the check to that ebuild instead *** This bug has been marked as a duplicate of bug 364129 ***