[cups] duplex not working ("Transport endpoint is not connected")

[Helge Blischke]

> Am 19.01.2016 um 12:15 schrieb Martin Vogt <martin.vogt at itwm.fraunhofer.de>:
> 
> 
> ...
> PS: The (interesting) strace for the client:
> 
> Start connect to cups server:
> 
> socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 5
> connect(5, {sa_family=AF_INET, sin_port=htons(631),
> sin_addr=inet_addr("10.x.y.z")}, 16) = -1 EINPROGRESS
> sendto(5, "POST /printers/cpsG0a HTTP/1.1..........")
> recvfrom(5, "\1\1\0\0\0\0\0\3\1G\0\22attributes-charset
> 
> [client gets some more data]
> 
> socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 7
> connect(7, {sa_family=AF_INET, sin_port=htons(631),
> sin_addr=inet_addr("192.a.b.c")}, 16) = -1 EINPROGRESS (Operation now in
> progress)
> getpeername(7, 0x7fff30216980, [256])   = -1 ENOTCONN (Transport
> endpoint is not connected)
> close(7)
> exit_group(0)

What strikes me is that there are two different networks are involved:
–	10.x.y.z
–	192.a.b.c
In addition to the strike, an error_log from both cupsd daemons involved (at least with log-level DEBUG,
maybe better DEBUG2) would be needed to dig more into the issue.

Helge