How to traceroute on a tcp port Cody Selzer August 15, 2020 00:57 Updated You can use traceroute to find networking issues on a specific tcp port. For example: traceroute -T -p 25 smtp.gmail.com Related articles How do I use AXFR to obtain a copy of a zone? What are the networking requirements for a cPanel installation? How to debug PHPMailer if you see "SMTP Error: Could not authenticate." How to test whether a port is opened outbound in my firewall. Comments 0 comments Article is closed for comments.