# Remote audit / syslog collector for the diskless fleet.
#
# Receives logs forwarded by booted diskless hosts and writes them
# per-source-host. Diskless hosts have an immutable, RAM-only overlay root,
# so their local audit log dies on reboot — this gives auditd somewhere durable
# to offload to (STIG remote-audit-offload, deviation #6 in docs/stig-deviations.md).
#
# Primary intake is syslog-over-TLS on 6514 (gtls; server cert issued by the
# fleet step-ca — see issue-cert.sh + README.md). Hosts authenticate the
# collector via the fleet CA baked in the image (x509/name); the collector does
# NOT require client certs (authMode "anon"): hosts are fleet-generic (no
# per-host state, invariant #1) and a baked fleet-wide client key would be
# shared secret material in the image. Sender access is instead constrained by
# the isolated boot LAN + the serving-host firewall scoping :6514 to it.

global(
    workDirectory="/var/spool/rsyslog"
    # TLS material for the 6514 listener, mounted from ./tls (issue-cert.sh).
    # NOTE: deliberately NOT setting DefaultNetstreamDriver="gtls" here — that
    # would flip every plain `protocol="tcp"` omfwd (the Wazuh relay below) to
    # TLS and break it. TLS is enabled per-listener instead.
    DefaultNetstreamDriverCAFile="/etc/rsyslog-tls/ca.crt"
    DefaultNetstreamDriverCertFile="/etc/rsyslog-tls/server.crt"
    DefaultNetstreamDriverKeyFile="/etc/rsyslog-tls/server.key"
)

# --- intake: syslog-over-TLS (the hardened image's 2f sender targets this) ---
module(load="imtcp" maxSessions="1000")
input(type="imtcp" port="6514"
      streamDriver.name="gtls" streamDriver.mode="1" streamDriver.authMode="anon")

# --- intake: plain TCP syslog (LEGACY/migration) ---
# Kept for already-released images that still forward plaintext to :514.
# Disable (comment out + close the firewall port) once the fleet is on
# TLS-sending images — production must not accept plaintext audit records.
input(type="imtcp" port="514" streamDriver.name="ptcp")
# Some senders only speak UDP; uncomment to also accept it (lossy, no queue).
#module(load="imudp")
#input(type="imudp" port="514")

# Disk-assisted main queue so a brief disk stall or a burst of records doesn't
# drop audit events (the records keep flowing to spool, then drain to disk).
main_queue(
    queue.type="LinkedList"
    queue.filename="mainq"
    queue.maxdiskspace="1g"
    queue.saveOnShutdown="on"
)

# --- relay a COPY of audit records to the Wazuh SIEM (separate node) -----------
# Forwards audit/local6 records to the Wazuh manager's syslog listener on the
# dedicated SIEM node (wazuh1.bitasylum.org) for parsing/correlation/alerting,
# WHILE still writing the durable per-host files below (no `stop`, so records
# continue to the file actions). Own disk-assisted queue -> a Wazuh outage never
# blocks the file writes or drops records (resumeRetryCount=-1 spools + drains on
# reconnect). The serving host must resolve + route to the SIEM node. After
# editing, rebuild: `docker compose build audit && docker compose up -d audit`.
#
# ⚠ PLAINTEXT 514 — only acceptable if serving-host → SIEM-node is a TRUSTED
# private path. Audit records are sensitive; if this hop crosses any routed/
# untrusted network, switch to syslog-over-TLS (gtls, port 6514, fleet CA) BEFORE
# relying on it (ISM: protect logs in transit). See serving/siem/README.md.
if ($programname == 'audispd')
   or ($programname startswith 'audit')
   or ($syslogfacility-text == 'local6') then {
    action(type="omfwd" target="wazuh1.bitasylum.org" port="514" protocol="tcp"
           action.resumeRetryCount="-1"
           queue.type="LinkedList" queue.filename="wazuhfwdq"
           queue.maxDiskSpace="256m" queue.saveOnShutdown="on")
}

# --- per-source-host files (keyed by SENDER IP, not the claimed hostname) ---
template(name="HostAudit"    type="string" string="/var/log/remote/%FROMHOST-IP%/audit.log")
template(name="HostMessages" type="string" string="/var/log/remote/%FROMHOST-IP%/messages.log")

# Audit records (audisp-syslog tags them 'audispd'/'audit', or forwards on the
# local6 facility) go to a dedicated per-host audit.log; everything else to
# messages.log. Files/dirs are created 0640/0750 (audit logs aren't world-read).
if ($programname == 'audispd')
   or ($programname startswith 'audit')
   or ($syslogfacility-text == 'local6') then {
    action(type="omfile" dynaFile="HostAudit"
           dirCreateMode="0750" fileCreateMode="0640")
    stop
}

action(type="omfile" dynaFile="HostMessages"
       dirCreateMode="0750" fileCreateMode="0640")