[pptp-server] GRE being blocked?

[Patrick J. LoPresti]

Brian Lalor <blalor at netDrives.com> writes:

> I'm seeing these errors in my logs for one particular client:
> GRE: read(fd=4,buffer=804d7e0,len=8196) from PTY failed: status = -1 error = Input/output error
> CTRL: PTY read or GRE write failed (pty,gre)=(4,5)
> 
> Does this mean GRE (proto 47?) is being blocked somewhere along the line?

No, it means that pptpd got an error while trying to read() from pppd.
(The "GRE:" prefix just means this error occurred in the HDLC-to-GRE
module; it does not necessarily mean there is any problem with the GRE
protocol itself.)  I do not know what to suggest, aside from turning
up logging from pppd to see what it is doing when these messages
occur.

Anyone happen to know what "Input/output error" even means for a PTY?

 - Pat