Currently, I met a problem, I cannot ssh to localhost in MacBook, but can ssh to other computers from MacBook. This is the output of the command.
ssh -v localhost
OpenSSH_7.6p1, LibreSSL 2.6.2
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 52: Applying options for *
debug1: Connecting to localhost port 22.
debug1: Connection established.
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/something/.ssh/id_ed25519-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.6
ssh_exchange_identification: read: Connection reset by peer