ssh

Understanding the SSH Encryption and Connection Process

what

secure shell: 加密网络协议

algorithm types:

1. RSA:
   1. -b: length 1024 to 8192 bits
2. ED25519:
   1. -a: 生成密钥函数的论数，论数越高，加密性越好

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ssh-keygen -t [types] -C comment

ssh-keygen -t rsa -b 4096

ssh-keygen -t ed25519 -a 100

the structure

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ssh-ed25519  # types 

AAAAC3NzaC1lZDI1NTE5AAAAIGZz3nOSfZv3bNtM1x+K5KfBdHJwaYGR0gR7x4HhF6Th user@hostname #pubic key

user@host  #public key, can change at will 

comment example:

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alice@workstation
alice@workstation-alice.smith@email.com

how it work

1. Negotiating: get the session key
   1. client: reqeust
   2. server: reply public key
      1. if first time, the user confirm, add to the known hosts
   3. negotiate a session key:TODO
2. authenticate:
   1. password:
      1. client: public key encrypt, server decrypt
   2. ssh key paris:
      1. server encrypt data with public key,client decrypt the data with its private key;