In Junos Fusion, the FTP user is automatically created and managed by the Junos Fusion SDPD (Satellite discovery and provisioning daemon) daemon. Attempts to disable or delete this user may lead to unintended consequences, as the SDPD daemon automatically reinstates the FTP user during certain events. This article provides insights into the creation and significance of the FTP user in the context of Junos Fusion.

The symptoms associated with managing the FTP user in Junos Fusion are as follows:

Automatic Creation of FTP User Directory:

Upon committing configurations under satellite-management, the SDPD daemon creates the /var/home/ftp/ directory. This directory structure is essential for Fusion operations.

sdpd_platform_init () code has following calls to do that:-
     sug_ftp_init();
     sug_homedir_init();

labroot@AD> file list /var/home/ftp/ detail 
/var/home/ftp/:
total blocks: 48
drwxr-xr-x  2 ftp   20           512 Apr 14 19:27 junos-images/
drwxr-xr-x  2 ftp   20           512 May 31 15:21 satellite-groups/
drwxr-xr-x  8 ftp   20           512 May 19 11:16 satellite-images/
drwxr-xr-x  2 ftp   20           512 Sep 21 07:07 sd_logs/
total files: 0

labroot@AD> file list /var/home/ftp/junos-images/ detail
/var/home/ftp/junos-images/:
/101/junos.tgz
/202/junos.tgz
/205/junos.tgz

labroot@AD> run file list /var/home/ftp/satellite-images/21.2R3-S6.11/
Dec 14 01:31:06
/var/home/ftp/satellite-images/21.2R3-S6.11/:
+COMMENT
arm/
arm563xx/
i386/
metatags
ppc/

FTP User Usage during Upgrades:

The FTP user is integral during satellite upgrades. If attempts are made to deactivate the FTP user, it can impact image transfers between the Aggregation Device (AD) and Satellite Device (SD).

show system login 
Dec 14 00:36:28
inactive: user ftp {
    uid 2003;
    class read-only;
}

show chassis satellite detail    
Dec 14 00:35:47
Satellite Alias: CAQU-S11
FPC Slot: 101
Operational State: ModeChangeFail
Product Model: QFX5100-48S-6Q
Product Family: i386
Serial number: VF3715300796
Device Reachability: None
Mode change state: Satellite image satellite-images/21.2R3-S6.11/i386/host.tgz installation request sent. Rx Response: FTP to aggregation device failed
System id: 0c:86:10:80:7a:00
Software package version: 21.2R3-S6.11
Cascade interfaces:
    Interface Name: xe-0/1/1:0 State: down
        Adjacency state: Dn
        Last transition: 1d 21:56:00
        Adjacency down count: 0 
        Rx Packet: 0

SDPD Daemon Response to FTP User Deactivation:

We cannot disable ftp user as this user is automatically created by the Junos Fusion SDPD daemon. 
This user is installed/needed by Fusion. If the user is deleted, then the next time that SDPD gets a SIGHUP, it detects that this user is missing and adds it back automatically.

labroot@device# show system login user ftp
##
## inactive: system login user ftp
##
uid 2003;
class read-only;

labroot@device# commit full 
re0:
configuration check succeeds
re1:
commit complete
re0:
commit complete

Dec 17 19:03:44.795 goa-re0 sdpd[60160]: sug_ftp_user_timer_expiry: user <ftp> does not exist.
Dec 17 19:03:45.887 goa-re0 ffp: "dynamic-profiles": No change to profiles
Dec 17 19:03:46.017 goa-re0 mgd[62514]: UI_COMMIT_COMPLETED: : commit complete
Dec 17 19:03:46.027 goa-re0 sdpd[60160]: sug_ftp_user_timer_expiry: user <ftp> created successfully

When dealing with the FTP user in Junos Fusion, it is advisable to keep it enabled to ensure smooth conversion processes. The FTP user is automatically created and managed by the SDPD daemon, and its presence is crucial for various Fusion functionalities, including the transition of nodes to satellite devices. Attempting to disable the FTP user manually may lead to unexpected issues, emphasizing the importance of maintaining its active status for proper Fusion operations.