openssh unix dev - Jun 2017 - Get remote address when using direct-streamlocal@openssh.com.

I've a server where clients can connect to using direct-streamlocal at
openssh.com.
I want that the server "knows" the address of the client. I've
tried
using the peercredentials
of the process connecting my server (which is a sshd process) and
check the environment.

I thought that in the environment the var SSH_CLIENT would be set, but
that did not work.
This sshd process has an almost empty environment file.

Is there another good way to find it?
Thanks in advance,

Stef Bon

Hi,

I can create something what works: the client has the ability to
create a channel using the same ssh session with the server,
and can execute commands. When the client has a connection with the
server using the direct-streamlocal mechanism,
it can also create a file on the server by running something like:

set > /tmp/sshd_set_%PPID%

the parent pid is the same pid my serverprocess reads when reading the
peer socket credentials.
My serverprocess  waits for the existence of this file, and when
detected, it reads the environmentvariables
like SSH_CLIENT.

This will work, but is very constructed. might there be another easier way?
Thanks in advance.

Stef

2017-06-02 8:15 GMT+02:00 Stef Bon <stefbon at
gmail.com>:
>
> This will work, but is very constructed. might there be another easier way?
Hi,

I'm thinking about using pam for this purpose. My fileserver watches a file
with
fanotify, getting the pid of the process which wants to open and write
to a file,
for example /run/ssh-remote-access

The sshd process uses a pammodule (pam_bfileserver for example in the
session phase of pam)
which writes information like:

%PID%:%PAM_RHOST%:%PAM_RUSER%

to this file. While it is busy doing so, other processes are blocked
to write to it.

When this data is written, bfileserver reads these values, compares
with the pid fanotify reported,
and if they match, bfileserver "knows" the remote address.
bfileserver clears the file, and allows access to it by other processes.
The pammodule should proceed if file not found.

Stef