FINDING · DETECTION

Only SSH/SFTP and sometimes RDP are observed to pass through the Russian mobile network freeze without data-size limitations; raw TCP transfers without TLS and all common TLS-based proxy protocols (VLESS, Reality, Trojan, Shadowsocks) are subject to the 15–20 KB per-connection cap. This suggests the censor's DPI whitelist is protocol-specific and SSH's wire format is recognized as exempt.

From 2025-hyperion-cs-censor-has-new — Censor has a new method of blocking · upd2 · 2025 · net4people/bbs

Implications

SSH tunneling (via port 22 or common SSH ports) currently bypasses the freeze and is a viable emergency transport for Russian mobile users — consider offering an SSH-transport mode in circumvention clients as a fallback.
Investigate whether disguising proxy traffic as SSH wire format (e.g., using the SSH binary protocol framing as a cover) would inherit the exemption, or whether the exemption is IP/port-based rather than content-based.