What networks are you using without ICMP? Presumably you're also using systems that don't support Unix Domain Sockets which can be configured as SOCK_STREAM, S

What networks are you using without ICMP? Presumably you're also using systems that don't support Unix Domain Sockets which can be configured as SOCK_STREAM, SOCK_DGRAM, and even gasp SOCK_SEQPACKET (equivalent to SOCK_DGRAM in this case admittedly).