auto-merge is a standalone set statement, not an nft "flags" value -
"flags interval, auto-merge;" is a syntax error; fixed to "flags
interval;" followed by "auto-merge" on its own line. Needed because large
public blocklists (FireHOL, Spamhaus) contain overlapping CIDRs that
nftables otherwise refuses as "conflicting intervals".
Also add a hard guard: reject any "block" entry that overlaps a private/
reserved/bogon range (RFC1918, CGNAT, loopback, link-local, etc.) in both
the single-entry and bulk-import paths. Public feeds like FireHOL level1
routinely include ranges like 10.0.0.0/8 and 172.16.0.0/12, meant for
WAN-only edge firewalls - applied host-wide here (where WireGuard/LAN
subnets legitimately live in that same private space), those entries
would silently block a server's own internal/VPN traffic instead of
actual bad actors.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
