Disable DHCP Service
Ensures the DHCP server (dhcpd.service) is disabled and not running unless the host is an intentional DHCP server.
Checked against the resolved running state (e.g. sshd -T, sysctl, systemctl show), catches drop-ins and Includes a file read would miss. Caveat: runtime ≠ persistence; a value correct now may not survive a reboot.
Pavois asserts the effective configuration, the live, resolved state, not a file. File-based scanners (OVAL/SCAP, Lynis) miss Includes, drop-ins and runtime defaults; this check sees what is actually applied.
A mapping is a cross-reference to where each standard places this requirement, anchored and cross-validated, not a claim of equivalence. A passing check is evidence toward these references, how to read it.
Why this rule matters
An unmanaged or unintentionally activated DHCP server can hand out faulty addresses, gateways or DNS to clients, hijacking traffic and interfering with the operation of a legitimate site DHCP server.
What Pavois checks
Pavois queries the resolved unit state with systemctl is-enabled / is-active for dhcpd.service. The effective state catches a server enabled by a drop-in or socket activation that reading /etc/dhcp/dhcpd.conf alone would not reveal.
describe service('isc-dhcp-server.service') do
it { should_not be_enabled }
it { should_not be_running }
endHow to verify it is applied
Run systemctl is-enabled dhcpd.service (expected disabled or not-found) and systemctl is-active dhcpd.service (expected inactive).
Inspect & investigate
Check systemctl show dhcpd.service (fields UnitFileState, ActiveState) and journalctl -u dhcpd.service; lease activity also appears in /var/log/syslog and /var/lib/dhcp/dhcpd.leases.
Remediation
Pavois's harden plan applies a service resource for dhcpd with actions disable and stop, so the DHCP server stays off across reboots and is stopped immediately. Apply it with pavois harden apply.
Pavois applies this with its own harden engine, the plan below, not a shell script:
| action | disable, stop |
|---|---|
| name | isc-dhcp-server.service |
| resource | service |
pavois harden plan localwhere the target is local, a user@host SSH alias, or a container , Docs
Impact & precautions
On a host that is not a DHCP server, disabling dhcpd.service has no functional impact. Precaution: if this machine legitimately serves DHCP leases, do not disable it, clients would lose addressing and connectivity; document the exception instead.
Standards mapping
| Standard | Reference | Type | Version | Confidence |
|---|---|---|---|---|
| CIS | 2.1.3 | direct | per OS, see the benchmark table | high |
| NIST | CM-7(a), CM-7(b), CM-6(a) | supporting | 800-53 Rev 5 · 800-171 Rev 2 (pinned) | medium |
Each reference is a cross-reference anchored in the upstream benchmark and cross-validated against the SCAP Security Guide and ansible-lockdown, not a claim of equivalence. Direct = a prescriptive, line-level requirement; supporting = an abstract control family (NIST) the check provides evidence toward. How to read a mapping.