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sharma Bal
sharma Bal

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šŸš€ Passing PCI in 2025: A Developerā€™s Server-Hardening Guide (Real Configs + Audit Notes)

#devops #pci #webdev #sysadmin

How we actually passed a PCI audit without losing our minds.

Most PCI guides online read like corporate checklists written by people who have never touched a server.
This one isnā€™t that.

This is the developer-focused, server-first, real-world version of PCI ā€” the stuff that actually breaks, actually gets flagged in ASV scans, and actually keeps your store out of trouble.

This is what we learned hardening WooCommerce / Magento / custom stacks for PCI DSS 4.0 in 2025.

Letā€™s get into it.
No marketing. No fluff. Just how it actually works.

šŸ”„ 1. Shared Hosting Will Fail PCI (Hereā€™s the Technical Reason Why)

PCI doesnā€™t officially ban shared hosting.
But in reality?

Account isolation on shared servers almost never meets segmentation requirements.

Why?

  • Multiple merchants share the same Apache/Nginx worker processes
  • Permission boundaries arenā€™t strict
  • One compromised neighbor ā†’ cross-contamination risk
  • You cannot enforce your own firewall rules
  • You cannot guarantee log isolation

ASV scanners flag it immediately.

āœ” Fix

Move to:

  • VPS
  • Cloud instance
  • Bare metal
  • Managed PCI-ready hosting

And prove segmentation:

iptables -L -n
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Look for traffic leaking between internal subnets.
If you see anything non-zero for non-essential ports?
ā†’ PCI will flag it.

šŸ§± 2. TLS 1.2 Allowedā€¦ TLS 1.3 Preferred (And Your Config Probably Fails)

Most PCI failures weā€™ve seen come from misconfigured TLS.

Hereā€™s the actual PCI-ready Nginx TLS block we use:

ssl_protocols TLSv1.3;
ssl_prefer_server_ciphers off;

ssl_ciphers "TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256";
ssl_ecdh_curve X25519:secp384r1;
ssl_session_timeout 1d;
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off;

add_header Strict-Transport-Security "max-age=63072000" always;
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Run this after deployment (css):

nmap --script ssl-enum-ciphers -p 443 yourdomain.com
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If TLS 1.2 appears ā†’ youā€™re not hardened enough.
If TLS 1.1 appears ā†’ you're failing PCI before the audit even begins.

šŸ” 3. Stop Storing Card Data (Developers Still Make This Mistake)

You, the developer, should never touch raw PAN.

Use tokenization (js):

const token = stripe.tokens.create({
  card: {
    number: '4242 4242 4242 4242',
    exp_month: 12,
    exp_year: 2025,
    cvc: '333'
  }
});
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The only place that should ever see the card number is:
Stripe/Braintree/Adyen.

If card data hits your logs even once?

Youā€™re dead.

Quick check (perl):

grep -R "card" /var/log/
grep -R "4242" /var/log/
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If you find anything, you must purge logs + fix code.

šŸ§± 4. Access Control: PCI Fails More Stores Than Hackers Do

PCI doesnā€™t like shared accounts.
And honestly? Neither should you.

Checklist dev version:

*āœ” No shared admin accounts
*

useradd -m john_dev
passwd john_dev
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*āœ” MFA on everything
*

  • SSH
  • cPanel
  • WordPress / Magento admin
  • Hosting panel

Add MFA to ssh with Google Auth (nginx):

apt install libpam-google-authenticator
google-authenticator
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*āœ” Disable old accounts immediately
*

sudo usermod --expiredate 1 oldemployee
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*āœ” Log every access
*
PCI wants audit trails.
You should too.

šŸ›”ļø 5. Vulnerability Scans: What Actually Gets Flagged

Approved Scanning Vendors (ASV) like Qualys or Trustwave will flag:

  • outdated OpenSSL
  • exposed phpMyAdmin
  • directory indexing
  • non-HTTPOnly cookies
  • mixed content
  • SSL renegotiation
  • missing HSTS
  • open ports (21, 22, 3306, 8080, 11211)

*Most of these are trivial to fix.
*
Example: disable directory indexing

autoindex off;
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*Example: lock ports
*

ufw default deny incoming
ufw allow 443
ufw allow 80
ufw deny 22 from 0.0.0.0/0
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*Example: secure cookies
*

Set-Cookie "session=abc123; HttpOnly; Secure; SameSite=Strict"
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šŸ” 6. Logging, SIEM, and ā€œContinuous PCIā€

PCI DSS 4.0 emphasizes ongoing monitoring, not yearly checklists.

*Minimum logging setup:
*

/var/log/auth.log
/var/log/nginx/access.log
/var/log/nginx/error.log
/var/log/syslog
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Enable auditd:


> apt install auditd
> auditctl -e 1
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Set real-time alerts with something simple like fail2ban or something enterprise like Wazuh.

fail2ban-client status sshd
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šŸ§Ŗ 7. Pen Testing: What PCI Actually Wants

PCI requires annual pen-testing and tests after major changes.

Tools weā€™ve successfully used:

nikto
nmap
wpscan
sqlmap
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Example quick sweep:

nikto -h https://yourstore.com
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šŸŽÆ PCI for Developers ā€” The Ultimate Checklist (2025 Edition)

  1. No shared hosting
  2. TLS 1.3 enforced
  3. No PAN stored anywhere
  4. MFA everywhere
  5. Unique accounts
  6. No open ports
  7. Vulnerability scan clean
  8. Logs monitored
  9. Annual pen test done
  10. Tokenization for all payments

If these 10 items pass, youā€™ve already walked 90% of the PCI road.

šŸ”š Final Thoughts

PCI isnā€™t ā€œcorporate compliance.ā€
Itā€™s basic operational security that every serious developer should understand.

Pass PCI not because ā€œyou have to,ā€
but because:

  • It hardens your stack
  • It reduces breach risk
  • It keeps your store online
  • It builds user trust

And honestly?
It feels good when the ASV scan finally comes back clean.

šŸ‘‰ Iā€™m working on a full developer-focused PCI series ā€” Iā€™ll publish the deeper breakdown soon.

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