linux c/c++ programming telnet connection io redirection

mPid = forkpty(&mPort, buffer, &mCurrTermattr, NULL);
...
if child
{
    execl("/usr/bin/telnet", "telnet", mComPort.name.c_str(), NULL);
}

system(gkermit -d gkermit.txt -X -e 8000 -i -s testfile.txt)

dup2(mPort, STDIN_FILENO)

dup2(mPort, STDOUT_FILENO)

dup2(mPort, STDOUT_FILENO)