By Phil Chiu, ThreatListPro · Published February 27, 2026 · Last verified: April 3, 2026
An IP blocklist is a curated list of IP addresses designed to be loaded directly into a firewall for automated blocking, while a threat intelligence feed is a broader product that includes IPs, domains, file hashes, and contextual data like threat actor attribution and confidence scores. Blocklists are action-oriented — block these IPs now. Threat feeds are intelligence-oriented — here is what we know about these indicators. The right choice depends on your threat model, team size, and budget. Both approaches align with the NIST Cybersecurity Framework's Protect function, which emphasizes proactive access control as a core defense layer.
This guide compares three tiers of IP threat intelligence—free open-source lists, curated blocklists like ThreatListPro, and enterprise threat feeds—so you can make an informed decision based on your actual security requirements and budget.
The Three Tiers at a Glance
| Feature | Free Open-Source | $9.99/mo ThreatListPro | $50-200+/mo Enterprise |
|---|---|---|---|
| Examples | FireHOL, ipsum, Spamhaus DROP | ThreatListPro Blocklist | Palo Alto PAN-DB, CrowdStrike, Recorded Future |
| IP Count | 100K to millions | 5.4M+ IPv4 addresses | 10K to millions |
| Focus | General threats (spam, scanning, C2) | VPN brute force attacks | Broad threat landscape |
| Update Frequency | Varies (daily to monthly) | Every 6 hours | Real-time to daily |
| False Positive Risk | High (CDNs, cloud IPs) | Low (curated, VPN-specific) | Low to moderate |
| Firewall Compatibility | Usually (may need reformatting) | All major firewalls (EDL-ready) | Vendor-specific integrations |
| SLA / Support | None | Email support, uptime guarantee | Full SLA, dedicated support |
| Setup Time | 30 min to hours (scripting needed) | 5 minutes | Hours to days |
Tier 1: Free Open-Source Lists
The most well-known free IP lists include FireHOL (aggregates dozens of threat feeds into tiered block lists), ipsum (a GitHub-hosted list scoring IPs by how many blocklists they appear on), and Spamhaus DROP/EDROP (hijacked IP blocks used by spammers and criminals). According to the Verizon Data Breach Investigations Report, stolen credentials remain the top initial access vector, making IP-based blocking a critical complementary defense.
These lists are valuable community resources, but they come with significant operational challenges when used for VPN protection:
Advantages
- Completely free
- Large coverage (millions of IPs)
- Community maintained and transparent
- Good for general-purpose blocking
Drawbacks
- Not focused on VPN attacks specifically
- High false positive rates (block CDNs, cloud IPs, legitimate hosts)
- Lists can exceed firewall entry limits
- Stale entries remain for months or years
- No SLA—list can go offline without warning
- May need scripting to convert formats
- No support when something breaks
The core problem with free lists for VPN protection is that they are not designed for this use case. FireHOL Level 1 contains tens of thousands of IPs involved in all types of malicious activity—spam, malware distribution, scanning, command-and-control. Many of these IPs have never attempted a single VPN login. Meanwhile, the VPN brute force IPs you actually need to block may not appear in these lists at all, because they focus on different threat categories.
Tier 2: Curated Blocklist (ThreatListPro)
ThreatListPro occupies the middle ground: a paid service focused specifically on VPN brute force threats, priced for small and mid-size IT teams at $9.99 per month.
The blocklist is built from real attacks on live production Palo Alto GlobalProtect VPN portals in the US. Every entry on the list comes from observed VPN attack activity.
In February 2026, the firewalls recorded 847,000 authentication attempts from 1,612 unique source IPs. These attacks map directly to MITRE ATT&CK T1110 (Brute Force), one of the most common initial access techniques observed in the wild. The top 50 IPs alone accounted for 41% of all attempts — credential stuffing at scale against GlobalProtect portals.
Advantages
- Purpose-built for VPN brute force protection
- Curated: every entry comes from observed attack activity
- Covers 5.4M+ addresses yet fits every firewall model
- EDL-ready format: plug the URL into your firewall and go
- Checked for new attackers every 6 hours
- 5-minute setup, zero ongoing maintenance
- $9.99/mo fits any budget
Limitations
- Focused only on VPN/authentication attacks
- Does not cover malware, C2, or other threat categories
- Checked for new attackers every 6 hours (not real-time)
- No STIX/TAXII or SIEM integration
- No threat actor attribution or contextual intelligence
Tier 3: Enterprise Threat Intelligence Feeds
At the enterprise level, vendors like Palo Alto Networks (PAN-DB, AutoFocus), CrowdStrike (Falcon Intelligence), Recorded Future, Mandiant Advantage, and Anomali offer comprehensive threat intelligence platforms with IP indicators, domain feeds, malware hashes, threat actor profiles, and integration with SIEMs and SOAR platforms.
Pricing varies widely. Entry-level commercial feeds start around $50 to $200 per month, but full enterprise platforms typically cost $10,000 to $100,000+ per year depending on the depth of intelligence, number of integrations, and level of support.
Pricing references: Gartner Peer Insights lists average enterprise threat intelligence spend at $25,000–$75,000/year for mid-market organizations. Entry-level commercial feeds from vendors like AlienVault OTX offer free community tiers with paid upgrades starting around $50/month.
Advantages
- Broad coverage across all threat categories
- Real-time or near-real-time updates
- Contextual intelligence (attribution, confidence, TTPs)
- STIX/TAXII and API integrations
- Full SLAs and dedicated support
- Feeds into SIEM, SOAR, and EDR workflows
Drawbacks
- Expensive ($50–200/mo minimum, enterprise tiers much more)
- Requires dedicated staff to operationalize
- General-purpose: may not prioritize VPN threats
- Complex integration and configuration
- Vendor lock-in with proprietary formats
- Overkill for single-problem use cases
Enterprise feeds are the right choice for organizations with a dedicated security operations center (SOC) that needs intelligence across the full threat landscape. If you have analysts who will use the contextual data to conduct investigations and hunt for threats, the investment pays for itself. If you just need to block VPN attackers at your firewall, you are paying for capabilities you will never use.
When Each Tier Makes Sense
Choose free open-source lists when:
- You have zero budget for security tooling
- You have a security engineer who can write scripts to fetch, parse, and format the lists
- You need general-purpose blocking (not VPN-specific)
- You accept the risk of false positives and stale data
Choose ThreatListPro ($9.99/mo) when:
- Your primary problem is VPN brute force attacks and account lockouts
- You need a solution that works in 5 minutes with zero ongoing effort
- Your budget is limited but you need reliable, production-grade protection
- You run Palo Alto, Fortinet, Cisco, or any firewall that supports EDLs
- You do not have a dedicated threat intelligence analyst on staff
Choose enterprise threat feeds ($50-200+/mo) when:
- You have a SOC with analysts who will use the intelligence for investigations
- You need coverage across all threat categories (malware, APT, fraud, etc.)
- You need real-time updates and STIX/TAXII integration
- You have budget for enterprise security tooling
- Compliance requirements mandate named threat intelligence sources
Frequently Asked Questions
What is the difference between a blocklist and a threat feed?
A blocklist is a simple list of IP addresses designed to be loaded into a firewall for automated blocking. A threat feed is a broader intelligence product that may include IPs, domains, URLs, file hashes, and contextual information like threat actor attribution and confidence scores. Blocklists are action-oriented; threat feeds are intelligence-oriented. For VPN protection, a focused blocklist is more practical and easier to deploy.
Are free IP blocklists safe to use on a firewall?
Free lists like FireHOL and ipsum are useful starting points, but they carry risks for production use. They often contain millions of IPs, many of which are stale or belong to shared infrastructure like CDNs and cloud providers. Blocking these can disrupt legitimate traffic. Free lists lack SLAs for uptime or accuracy. For protecting critical infrastructure like VPN portals, a curated list with quality control is strongly recommended.
How much does a threat intelligence feed cost?
Free open-source lists cost nothing. Curated blocklists like ThreatListPro cost $9.99 per month. Commercial threat intelligence feeds start at $50 to $200+ per month for basic tiers, with full enterprise platforms costing $10,000 to $100,000+ per year depending on data volume, integrations, and support.
Can I use multiple blocklists at the same time?
Yes. Most firewalls support multiple EDLs simultaneously. You could use ThreatListPro for VPN threats and a separate list for broader indicators. Be mindful of your firewall’s total entry limit across all EDLs, and watch for overlap between lists, which wastes capacity.