many of de‐ velopers just produce. In 4 words - "it is not good" So that's the story about secured SSH server.Simple fix Resources: EC2SecurityGroup: Type: AWS:: EC2:: SecurityGroup Properties: - CidrIp: 0.0.0.0/0 IpProtocol: -1Low-hanging fruit – install fail2ban – change SSH port. Use for example 31 – lock password login – enable regular firewall – disable default users /Users/kuba/.ssh/id_ed25519_gowaw56 User kuba Hostname 10.0.10.60 Port 22 Host Bastion PreferredAuthentications publickey IdentitiesOnly=yes IdentityFile /Users/kuba/.ssh/id_ed25519_gowaw56

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to per-worker level # Can be a dict if multiple fields need to be stored. userdata::Any # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to per-worker level # Can be a dict if multiple fields need to be stored. userdata::Any # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to be stored. userdata::AnyCHAPTER 26. MULTI-PROCESSING AND DISTRIBUTED COMPUTING 350 # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to be stored. userdata::AnyCHAPTER 26. MULTI-PROCESSING AND DISTRIBUTED COMPUTING 350 # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to be stored. userdata::AnyCHAPTER 26. MULTI-PROCESSING AND DISTRIBUTED COMPUTING 350 # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to be stored. userdata::AnyCHAPTER 26. MULTI-PROCESSING AND DISTRIBUTED COMPUTING 353 # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to be stored. userdata::AnyCHAPTER 26. MULTI-PROCESSING AND DISTRIBUTED COMPUTING 354 # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to be stored. userdata::AnyCHAPTER 26. MULTI-PROCESSING AND DISTRIBUTED COMPUTING 353 # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}

shown above. • A cluster spanning machines using the --machine-file option. This uses a passwordless ssh login to start Julia worker processes (from the same path as the current host) on the specified machines [count*][user@]host[:port] [bind_addr[:port]]. user defaults to current user, port to the standard ssh port. count is the number of workers to spawn on the node, and defaults to 1. The optional bind-to per-worker level # Can be a dict if multiple fields need to be stored. userdata::Any # SSHManager / SSH tunnel connections to workers tunnel::Union{Bool, Nothing} bind_addr::Union{AbstractString, Nothing}