@josephoshaughnessy

Joseph O'Shaughnessy

@josephoshaughnessyLondon, UKJoined October 2026

Network engineer. Labs, packet captures and real-world troubleshooting.

About

Network engineer at an MSP, after starting out in the core network team at a small ISP. I lab things at home, break them, and write up what I learn, from packet captures and firewalls to routing and troubleshooting.

Available for

I am available for freelance work and technical writing

Joseph O'Shaughnessy's blogs

Joseph O'Shaughnessyjosephoshaughnessy.hashnode.dev2 posts

josephoshaughnessy.hashnode.dev1d ago · 12 min read

Finding an MTU Black Hole with ping, tcpdump and Wireshark

You can SSH to the server. The login page loads. Ping works. But the moment someone downloads a large file or opens a big report, it just sits there, and eventually times out. Everyone swears the netw

josephoshaughnessy.hashnode.dev1d ago · 12 min read

Diagnosing a Failed TCP Handshake in Wireshark

When someone says "the application is down", the quickest way to settle whether it's the network is to look at the TCP handshake. If the three-way handshake never completes, the application never gets

Joseph O'Shaughnessy

About

Available for

Joseph O'Shaughnessy's blogs

Finding an MTU Black Hole with ping, tcpdump and Wireshark

Diagnosing a Failed TCP Handshake in Wireshark

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Joseph O'Shaughnessy

About

Available for

Joseph O'Shaughnessy's blogs

Finding an MTU Black Hole with ping, tcpdump and Wireshark

Diagnosing a Failed TCP Handshake in Wireshark