Ssh 2.0

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  1. OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re-added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0. BSD April 14, 2013 BSD Referenced By.
  2. SSH-2.0-OpenSSH6.6.1p1 Ubuntu-2ubuntu2 Protocol mismatch. How to fix this problem? Best Regards, Marcelo Amorim. Re: vagrant-up SSH-2.0-OpenSSH - Protocol mismatch. Alvaro Miranda Aguilera: 1/15/15 12:21 PM: Hello, when you access that port 2222 in the host, you are redirected/nat into the port 22 in the guest that is ssh.

ssh-keygen - authentication key generation, management and conversion

Ssh 2.0 Dropbear

Synopsis

OpenSSH is a 100% complete SSH protocol 2.0 implementation and includes sftp client and server support. Once again, we would like to thank the OpenSSH community for their continued support of the project, especially those who contributed code or patches, reported bugs. Apr 19, 2021 You can use the -tunnel-through-iap flag so that gcloud compute ssh always uses IAP TCP tunneling. Use the -internal-ip flag so that gcloud compute ssh never uses IAP TCP tunneling and instead directly connects to the internal IP of the VM. Doing so is useful for clients that are connected to the same VPC network as the target VM.

ssh-keygen [-q] [-bbits] -ttype [-Nnew_passphrase] [-Ccomment] [-foutput_keyfile]

ssh-keygen -p [-Pold_passphrase] [-Nnew_passphrase] [-fkeyfile]

ssh-keygen -i [-finput_keyfile]

Ssh-2.0-crushftpsshd

Ssh

ssh-keygen -e [-finput_keyfile]

ssh-keygen -y [-finput_keyfile]

ssh-keygen -c [-Ppassphrase] [-Ccomment] [-fkeyfile]

ssh-keygen -l [-finput_keyfile]

ssh-keygen -B [-finput_keyfile]

ssh-keygen -Dreader

ssh-keygen -Fhostname [-fknown_hosts_file] [-l]

Mac os for lenovo z580. ssh-keygen -H [-fknown_hosts_file]

ssh-keygen -Rhostname [-fknown_hosts_file]

Ssh-2.0-openssh_8.1

ssh-keygen -Ureader [-finput_keyfile]

ssh-keygen -rhostname [-finput_keyfile] [-g]

ssh-keygen -Goutput_file [-v] [-bbits] [-Mmemory] [-Sstart_point]

ssh-keygen -Toutput_file-finput_file [-v] [-anum_trials] [-Wgenerator]

ssh-keygen [-n] [-Dsmartcard]

Description

ssh-keygen generates, manages and converts authentication keys for ssh(1). ssh-keygen can create RSA keys for use by SSH protocol version 1and RSA or DSA keys for use by SSH protocol version 2. The type of key to be generated is specified with the -t option. If invoked without anyarguments, ssh-keygen will generate an RSA key for use in SSH protocol 2 connections.

ssh-keygen is also used to generate groups for use in Diffie-Hellman group exchange (DH-GEX). See the MODULI GENERATION section for details.

Normally each user wishing to use SSH with RSA or DSA authentication runs this once to create the authentication key in ~/.ssh/identity,~/.ssh/id_dsa or ~/.ssh/id_rsa. Additionally, the system administrator may use this to generate host keys, as seen in /etc/rc.

Normally this program generates the key and asks for a file in which to store the private key. The public key is stored in a file with the same name but'.pub' appended. The program also asks for a passphrase. The passphrase may be empty to indicate no passphrase (host keys must have an empty passphrase), orit may be a string of arbitrary length. A passphrase is similar to a password, except it can be a phrase with a series of words, punctuation, numbers,whitespace, or any string of characters you want. Good passphrases are 10-30 characters long, are not simple sentences or otherwise easily guessable (Englishprose has only 1-2 bits of entropy per character, and provides very bad passphrases), and contain a mix of upper and lowercase letters, numbers, andnon-alphanumeric characters. The passphrase can be changed later by using the -p option.

There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key must be generated and copied to the corresponding public keyto other machines.

For RSA1 keys, there is also a comment field in the key file that is only for convenience to the user to help identify the key. The comment can tell whatthe key is for, or whatever is useful. The comment is initialized to 'user@host' when the key is created, but can be changed using the -c option.

After a key is generated, instructions below detail where the keys should be placed to be activated.

The options are as follows:

Specifies the number of primality tests to perform when screening DH-GEX candidates using the -T command.

-B' Show the bubblebabble digest of specified private or public key file.

-bbits
Specifies the number of bits in the key to create. For RSA keys, the minimum size is 768 bits and the default is 2048 bits. Generally, 2048 bits is consideredsufficient. DSA keys must be exactly 1024 bits as specified by FIPS 186-2.

-Ccomment
Provides a new comment.

-c' Requests changing the comment in the private and public key files. This operation is only supported for RSA1 keys. The program will prompt forthe file containing the private keys, for the passphrase if the key has one, and for the new comment.

-Dreader
Download the RSA public key stored in the smartcard in reader.

-e' This option will read a private or public OpenSSH key file and print the key in RFC 4716 SSH Public Key File Format to stdout. This option allowsexporting keys for use by several commercial SSH implementations.

-Fhostname
Search for the specified hostname in a known_hosts file, listing any occurrences found. This option is useful to find hashed host names oraddresses and may also be used in conjunction with the -H option to print found keys in a hashed format.

-ffilename
Specifies the filename of the key file.

-Goutput_file
Generate candidate primes for DH-GEX. These primes must be screened for safety (using the -T option) before use.

-g' Use generic DNS format when printing fingerprint resource records using the -r command.

-H' Hash a known_hosts file. This replaces all hostnames and addresses with hashed representations within the specified file; the originalcontent is moved to a file with a .old suffix. These hashes may be used normally by ssh and sshd, but they do not reveal identifying informationshould the file's contents be disclosed. This option will not modify existing hashed hostnames and is therefore safe to use on files that mix hashed andnon-hashed names.

-i' This option will read an unencrypted private (or public) key file in SSH2-compatible format and print an OpenSSH compatible private (or public)key to stdout. ssh-keygen also reads the RFC 4716 SSH Public Key File Format. This option allows importing keys from several commercial SSHimplementations.

-l' Show fingerprint of specified public key file. Private RSA1 keys are also supported. For RSA and DSA keys ssh-keygen tries to find thematching public key file and prints its fingerprint. If combined with -v, an ASCII art representation of the key is supplied with the fingerprint.

-Mmemory
Specify the amount of memory to use (in megabytes) when generating candidate moduli for DH-GEX.

-n' Extract the public key from smartcard.

-Nnew_passphrase
Provides the new passphrase.

-Ppassphrase
Provides the (old) passphrase.

-p' Requests changing the passphrase of a private key file instead of creating a new private key. The program will prompt for the file containing theprivate key, for the old passphrase, and twice for the new passphrase.

-q' Silence ssh-keygen. Used by /etc/rc when creating a new key.

-Rhostname
Removes all keys belonging to hostname from a known_hosts file. This option is useful to delete hashed hosts (see the -H option above).

-rhostname
Print the SSHFP fingerprint resource record named hostname for the specified public key file.

-Sstart
Specify start point (in hex) when generating candidate moduli for DH-GEX.

-Toutput_file
Test DH group exchange candidate primes (generated using the -G option) for safety.

-ttype
Specifies the type of key to create. The possible values are 'rsa1' for protocol version 1 and 'rsa' or 'dsa' for protocol version 2.

-Ureader
Upload an existing RSA private key into the smartcard in reader.

-v' Verbose mode. Causes ssh-keygen to print debugging messages about its progress. This is helpful for debugging moduli generation. Multiple-v options increase the verbosity. The maximum is 3.

-Wgenerator
Specify desired generator when testing candidate moduli for DH-GEX.

-y' This option will read a private OpenSSH format file and print an OpenSSH public key to stdout.

Moduli Generation

ssh-keygen may be used to generate groups for the Diffie-Hellman Group Exchange (DH-GEX) protocol. Generating these groups is a two-step process:first, candidate primes are generated using a fast, but memory intensive process. These candidate primes are then tested for suitability (a CPU-intensiveprocess).

Generation of primes is performed using the -G option. The desired length of the primes may be specified by the -b option. Forexample:

# ssh-keygen -T moduli-2048 -f moduli-2048.candidates

By default, each candidate will be subjected to 100 primality tests. This may be overridden using the -a option. The DH generator value will bechosen automatically for the prime under consideration. If a specific generator is desired, it may be requested using the -W option. Valid generatorvalues are 2, 3, and 5.

Screened DH groups may be installed in /etc/ssh/moduli. It is important that this file contains moduli of a range of bit lengths and that both endsof a connection share common moduli.

Files

Contains the protocol version 1 RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specifya passphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 3DES. This file is not automatically accessedby ssh-keygen but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made.

~/.ssh/identity.pub
Contains the protocol version 1 RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machineswhere the user wishes to log in using RSA authentication. There is no need to keep the contents of this file secret.

~/.ssh/id_dsa
Contains the protocol version 2 DSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify apassphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 3DES. This file is not automatically accessedby ssh-keygen but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made.

~/.ssh/id_dsa.pub
Contains the protocol version 2 DSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machineswhere the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret.

~/.ssh/id_rsa
Contains the protocol version 2 RSA authentication identity of the user. This file should not be readable by anyone but the user. It is possible to specify apassphrase when generating the key; that passphrase will be used to encrypt the private part of this file using 3DES. This file is not automatically accessedby ssh-keygen but it is offered as the default file for the private key. ssh(1) will read this file when a login attempt is made.

~/.ssh/id_rsa.pub
Contains the protocol version 2 RSA public key for authentication. The contents of this file should be added to ~/.ssh/authorized_keys on all machineswhere the user wishes to log in using public key authentication. There is no need to keep the contents of this file secret.

/etc/ssh/moduli
Contains Diffie-Hellman groups used for DH-GEX. The file format is described in moduli(5).

Environment

The reseeding of the OpenSSL random generator is usually done from /dev/urandom. If the SSH_USE_STRONG_RNG environment variable is set tovalue other than 0 the OpenSSL random generator is reseeded from /dev/random. The number of bytes read is defined by the SSH_USE_STRONG_RNGvalue. Minimum is 6 bytes. This setting is not recommended on the computers without the hardware random generator because insufficient entropy causes theconnection to be blocked until enough entropy is available.

See Also

ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8)

Authors

OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt andDug Song removed many bugs, re-added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0.

BSD April 14, 2013 BSD

Referenced By

amaddclient

Ssh-2.0-mod_sftp

(8),autossh(1),backup-manager(8),

Ssh-2.0-openssh_7.4 Exploit

gsimoduli(5),gsissh(1),gsissh-keysign(8),gsissh_config(5),gsisshd(8),rsnapshot(1),scp(1),sftp(1),ssh-keysign(8),ssh_config(5),tlsa(1)