TT Stunnel Changes: Removing Certificate Pinning

 

The following comes from TT System Admin News & Updates for September 4, 2026

 

As of Q2 2026 TT no longer provides / updates the stunnel.zip file which customers might be using to perform certificate pinning. The final certificate in the stunnel.zip file expires on Oct 17, 2026.  

Only customers who download the stunnel.zip file from https://library.tradingtechnologies.com/tt-fix/general/stunnel.zip are impacted. Affected customers should start migrating to utilize their local machine’s certificate trust store. Digicert and AWS are both established Certificate Authorities and should be available in the trust stores of modern operating systems.

 

What This Means 

• Clients no longer need to download TTFIX.crt file 
• Clients configure stunnel to use their OS trust store path for CA validation 
• We verify the correct authentication chain rather than a single pinned leaf certificate 

Configuration Changes 

 

Previous (pinned certificate)

[orfix-tcp]  

client = yes  

accept = 127.0.0.1:11702  

connect = FullyQualifiedDomainName:port  

CAfile = TTFIX.crt  

verify = 3 

 

New (OS trust store with chain validation) 

[orfix-tcp]  

client = yes  

accept = 127.0.0.1:11702  

connect = FullyQualifiedDomainName:port  

verifyChain = yes  

CAfile = <OS_SPECIFIC_TRUST_STORE_PATH> 

 

Notes and Additional Guidance 

• The snippet above is a single section of the client configuration.  For the other sections please see our online documentation here 
• Stunnel versions: verifyChain = yes is broadly compatible. If required, verify = 2 provides comparable chain validation. 
• For clients that currently connect to TT FIX using stunnel, we ask that they come into the UAT to test their needed configuration changes.   

Invest numbers / Disturbance identifiers

 

Those codes are invest numbers / disturbance identifiers used by tropical cyclone warning agencies to track systems before—or sometimes after—they become named tropical depressions or storms.

The format is basically:

NN + basin letter

where NN is a sequential number and the final letter identifies the ocean basin.

Example	Meaning	Basin
05L	System number 05	North Atlantic
12E	System number 12	Eastern North Pacific
01W	System number 01	Western North Pacific

The basin letters are the important part:

• L = North Atlantic, including the Caribbean Sea and Gulf of Mexico
• E = Eastern North Pacific
• C = Central North Pacific
• W = Western North Pacific
• A / B = North Indian Ocean
• S / P = Southern Hemisphere basins, depending on location

An important distinction

You might see something like Invest 95L. That is not the fifth tropical cyclone of the year.

Numbers 90–99 are normally reserved for invests—areas of disturbed weather that forecasters are specifically investigating for possible tropical development. The numbers can later be reused.