dropbear

Start SSH server

$ dropbear

$ dropbear -p [2222]

$ dropbear -F

$ dropbear -r [/etc/dropbear/dropbear_rsa_host_key]

$ dropbear -s

$ dropbear -g

dropbear [options]

dropbear is a lightweight SSH server designed for embedded systems and resource-constrained environments. It implements SSH 2 protocol with support for public key and password authentication.
Despite its small size, dropbear provides essential SSH functionality including remote login, port forwarding, and scp/sftp. It's commonly found in routers, embedded Linux, and initramfs.

-p [addr:]port

Listen on port (multiple allowed).

Run in foreground.

Log to stderr instead of syslog.

Use specific host key file.

Disable password authentication.

Disable root password auth.

Allow blank passwords.

Disallow root login.

Disable local port forwarding.

Disable remote port forwarding.

Idle timeout.

PID file location.

Fewer features than OpenSSH. No sftp-server included (use external). Key format differs from OpenSSH. Limited algorithm support in older versions.

dropbear was created by Matt Johnston in 2003 as a minimal SSH implementation for embedded systems. It fills the need for SSH in environments where OpenSSH is too large, such as routers running OpenWrt and rescue systems.

dbclient(1), dropbearkey(1), sshd(1), scp(1)