Safe mode in ssh is very slow to keypress response. cpu and network usage increasing

RouterOS General
1

RouterOS Version: 7.19.2
Device: hEX and RB4011iGS+

Reproduce:

  1. ssh login to RouterOS
  2. Press CTRL+X to enter safe mode

CPU of local ssh terminal increasing. All cpu cores usage of Router Device goes high. Network bandwidth takes several Mbps even idle in safe mode.

In winbox, no extra overhead after turning on safe mode. While some remote devices, winbox service are disabled, only ssh access allowed. Such huge overhead it is impossible to do anything in safe mode in ssh terminal.

2

Same here, but

  • Linux ssh client (Debian 12.13 and 13.4) => no problems
  • Microsoft ssh client (Windows 10 22H2) => no problems
  • Microsoft ssh client (Windows 11 25H2) => safe mode unusable
  • Putty 0.83 ssh client (Windows 11 25H2) => no problems
  • Winbox 4.1 terminal (Windows 11 25H2) => no problems

So the issue is apparently Microsoft Windows 11 ssh client related (but it may or may not be the root cause).

Platform

  • RouterOS version: 7.20.8 (latest long-term)
  • Devices: RB5009, wAP ax
  • Host key type: rsa, ed25519

I have created a support request (SUP-214768).

3

MikroTik has acknowledged the issue. A fix will take some time.

Edit: fixed in 7.23rc3.