From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Carlson Date: Wed, 28 Oct 2009 20:20:06 +0000 Subject: Re: pty Message-Id: <4AE8A776.5060202@workingcode.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ppp@vger.kernel.org tony.chamberlain@lemko.com wrote: > I am curious how the pppd pty process (in this case ppp_relay) communicates > to pppd? We did a netstat and found pppd but no TCP nor UDP ports were > associated with it. It was just a UNIX-type process. The ppp_relay process will have stdin and stdout connected to the master side of a pty pair. Pppd then configures PPP to run on the slave side. Pppd is completely unaware of what that child process is doing; it won't have any network ports open. The process run by the pppd "pty" option should read and write AHDLC-encoded PPP packets on standard input and output. Where and how it gets those packets are a problem for the person writing ppp_relay. Or, as the fine man page says: pty script Specifies that the command script is to be used to communicate rather than a specific terminal device. Pppd will allocate itself a pseudo-tty master/slave pair and use the slave as its terminal device. The script will be run in a child process with the pseudo-tty master as its standard input and output. An explicit device name may not be given if this option is used. (Note: if the record option is used in conjuction with the pty option, the child process will have pipes on its standard input and output.) -- James Carlson 42.703N 71.076W