Are there free C/C++ and Java implementations of the point-to-point protocol (PPP) for use over a serial line? The C/C++ implementation will go into embedded hardware so portability is a concern. I'm not looking for a full TCP/IP stack, just something to provide a connection-oriented base to build on top of.
The one used in most Linux-based systems is in C and is named Paul's PPP Package.
FreeBSD has a completely different one, also written in C, but I have no experience with it.
In linux I use chat and pppd for using ppp over serial line in linux. ( Adding a gprs modem to get internet connection )
I found a library named TINI that includes a ppp java implementation
And more description here
Hope it helps