U4039 Abend Connecting to SFTP Server

[hroman]

When we try to connect to the SFTP server, we see a u4039 abend and the connection is closed. A CEEDUMP is produced. The tail end of a trace from the client side shows the following:

u163284@tso8.whq.ual.com's password:
debug3: packet_send2: adding 64 (len 60 padlen 4 extra_pad 64)
debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
debug2: fd 4 setting O_NONBLOCK
debug2: fd 5 setting O_NONBLOCK
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug1: Entering interactive session.
debug2: callback start
debug2: client_session2_setup: id 0
debug1: Sending subsystem: sftp
debug2: channel 0: request subsystem confirm 1
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel 0: rcvd adjust 2097152
debug2: channel 0: rcvd eof
debug2: channel 0: output open -> drain
debug2: channel 0: obuf empty
debug2: channel 0: close_write
debug2: channel 0: output drain -> closed
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug2: channel 0: rcvd close
debug2: channel 0: close_read
debug2: channel 0: input open -> closed
debug3: channel 0: will not send data after close
debug2: channel 0: almost dead
debug2: channel 0: gc: notify user
debug2: channel 0: gc: user detached
debug2: channel 0: send close
debug2: channel 0: is dead
debug2: channel 0: garbage collecting
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
#0 client-session (t4 r0 i3/0 o3/0 fd -1/-1 cfd -1)

debug3: channel 0: close_fds r -1 w -1 e 6 c -1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
debug1: Transferred: stdin 0, stdout 0, stderr 0 bytes in 12.6 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 0.0
debug1: Exit status 146
[29.986] Connection closed

We are running Co:Z SFTP 2.0.1. This seems to only be happening on one LPAR.

Any ideas? How do we troubleshoot this?

Jerry Roman

[dovetail]

Hi Jerry,

The most likely cause would be some kind of z/OS Unix or LE configuration issue.
What is the U4039 reason code?
Can you tell if the abend is in IBM Ported Tools OpenSSH (sshd) or Co:Z sftp-server?

Please send a copy of the CEEDUMP to info@dovetail.com and we'll take a look.

[dovetail]

Determined that the ABEND was in another vendor's user exit - which required that Co:Z SFTP server be setup to run APF authorized.