Why does SSH send 100 packets per keystroke? · eieio.games

A developer building a high-performance SSH-based multiplayer game discovered that OpenSSH sends ~100 chaff packets per keystroke due to keystroke timing obfuscation (added in 2023). This feature sends SSH2_MSG_PING messages to servers advertising the ping@openssh.com extension, obscuring typing patterns from network observers. While valuable for privacy, it caused 66% of all packets to be overhead, doubling CPU usage and bandwidth. The fix was forking Go's x/crypto library to remove the ping@openssh.com extension advertisement, cutting total CPU from 29.9% to 11.6%, syscall time by 79%, crypto overhead by 93%, and bandwidth in half. The post also reflects on using Claude Code for network packet analysis.