F5 Certificate Installation Guide

The 30-Second Version

The process: Import certificate → Import key → Import chain → Create/update Client SSL profile → Assign to virtual server.

Location: System → Certificate Management → Traffic Certificate Management → SSL Certificate List

Common gotcha: Don't forget the intermediate certificate chain - it's a separate import.

Before You Start

What You Need

Item	Description	File Extension
Server Certificate	Your SSL certificate from the CA	.crt, .cer, .pem
Private Key	Generated when you created the CSR	.key, .pem
Intermediate Chain	From your CA (often called "CA Bundle")	.crt, .pem, .ca-bundle
Key Passphrase	Only if your key is password-protected	(text)

Pre-Flight Checklist

Certificate and key files are accessible
You know the key passphrase (if encrypted)
You have intermediate certificate(s) from your CA
You have admin access to F5 BIG-IP
You know which virtual server needs this certificate

Import the Certificate and Key

Path: System → Certificate Management → Traffic Certificate Management → SSL Certificate List → Import

Option A: Import Key + Certificate Together (Recommended)

Click Import
Import Type: Select Certificate + Key
Certificate Name: Use a descriptive name (e.g., www.example.com_2025)
Certificate Source: Upload file or paste PEM text
Key Source: Upload file or paste PEM text
Key Passphrase: Enter if key is encrypted (leave blank if not)
Click Import

Option B: Import Separately

Import Certificate:

Click Import
Import Type: Select Certificate
Certificate Name: www.example.com_2025
Certificate Source: Upload or paste
Click Import

Import Key:

Click Import
Import Type: Select Key
Key Name: Use same name as certificate for easy matching
Key Source: Upload or paste
Key Passphrase: Enter if encrypted
Click Import

Verification

After import, you should see your certificate listed with:

Certificate name
Expiration date
Key (shows "Yes" if key is present)

Import the Intermediate Chain

This step is critical.

Missing intermediates cause "certificate not trusted" errors on mobile devices and API clients.

Path: System → Certificate Management → Traffic Certificate Management → SSL Certificate List → Import

Click Import
Import Type: Select Certificate (not Key)
Certificate Name: Descriptive name (e.g., DigiCert_Intermediate_2025 or Sectigo_Chain)
Certificate Source: Upload or paste your intermediate certificate
Click Import

Multiple Intermediates?

If your CA provided multiple intermediate files, you have two options:

Option 1: Import Each Separately

Import each intermediate as its own certificate. Later, you'll need to create a bundle (more complex).

Option 2: Create a Bundle File First (Recommended)

# Concatenate intermediates (order matters: your issuer first)
cat intermediate1.crt intermediate2.crt > chain-bundle.crt

Then import the bundle as a single certificate.

Create or Update the Client SSL Profile

Path: Local Traffic → Profiles → SSL → Client

Creating a New Profile

Click Create
Name: Descriptive name (e.g., clientssl_www.example.com)
Parent Profile: Select clientssl (default parent)

Configure Certificate Key Chain

Scroll to Certificate Key Chain section
Click Add
Certificate: Select your imported certificate
Key: Select your imported key (should auto-match if names match)
Chain: Select your intermediate certificate
Passphrase: Enter if key is encrypted
Click Add
Click Finished

Visual of Certificate Key Chain

┌─────────────────────────────────────────────────┐
│ Certificate Key Chain                           │
├─────────────────────────────────────────────────┤
│ Certificate: www.example.com_2025          [▼]  │
│ Key:         www.example.com_2025          [▼]  │
│ Chain:       DigiCert_Intermediate_2025    [▼]  │
│ Passphrase:  ••••••••                           │
│                                      [Add]      │
└─────────────────────────────────────────────────┘

Assign Profile to Virtual Server

Path: Local Traffic → Virtual Servers → [Your Virtual Server]

Select your virtual server
Scroll to SSL Profile (Client) section
Move your new profile from Available to Selected
Click Update

Quick Check

Your virtual server should now show:

SSL Profile (Client): clientssl_www.example.com

Verify the Installation

Test from Command Line

# Basic connection test
openssl s_client -connect your-vip-ip:443 -servername www.example.com

# Check certificate details
openssl s_client -connect your-vip-ip:443 -servername www.example.com 2>/dev/null | \
  openssl x509 -noout -subject -issuer -dates

# Verify chain is being sent (should show 2+ certificates)
openssl s_client -connect your-vip-ip:443 -servername www.example.com 2>/dev/null | \
  grep -c "BEGIN CERTIFICATE"

Test with SSL Labs

Go to ssllabs.com/ssltest
Enter your domain
Check for:

Certificate valid
Chain complete
No chain issues

Test from F5 (tmsh)

# List certificates
tmsh list sys crypto cert

# Show certificate details
tmsh list sys crypto cert www.example.com_2025 all-properties

# Verify profile configuration
tmsh list ltm profile client-ssl clientssl_www.example.com

Common Installation Errors

Error	Cause	Fix
"Key and certificate do not match"	Wrong private key uploaded	Re-export key from where you generated CSR
"Invalid certificate"	Wrong format or corrupted file	Ensure PEM format, check for hidden characters
"Unable to load key"	Wrong passphrase or encrypted key	Verify passphrase or decrypt key first
Certificate shows but not working	Profile not assigned to VS	Check Virtual Server → SSL Profile (Client)
"Not trusted" on some clients	Missing chain certificate	Import and assign intermediate in Chain field
Key import fails	Key still encrypted	Decrypt with: `openssl rsa -in encrypted.key -out decrypted.key`

Quick Reference - tmsh Commands

# Import certificate via tmsh
tmsh install sys crypto cert www.example.com_2025 from-local-file /var/tmp/cert.crt

# Import key via tmsh
tmsh install sys crypto key www.example.com_2025 from-local-file /var/tmp/cert.key

# Create client SSL profile
tmsh create ltm profile client-ssl clientssl_www.example.com \
  cert-key-chain add { www.example.com_2025 { \
    cert www.example.com_2025 \
    key www.example.com_2025 \
    chain DigiCert_Intermediate_2025 \
  }}

# Assign profile to virtual server
tmsh modify ltm virtual my-virtual-server profiles add { clientssl_www.example.com { context clientside } }

# Save configuration
tmsh save sys config

Installation Checklist

Certificate imported
Private key imported (matches certificate)
Intermediate chain imported
Client SSL profile created
Certificate Key Chain configured with cert + key + chain
Profile assigned to virtual server
Tested with openssl s_client
Verified chain is complete (no "not trusted" errors)
Configuration saved

F5 BIG-IP Certificate Installation