Ssh Sha1

Posted : admin On 1/29/2022
  • .-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kexparsekexinit: ssh-rsa. Ssh/knownhosts debug3: checkhostinhostfile: match.
  • SHA1 decrypter / decoder. Rainbow table lookup for reverse lookup of SHA1 hashes.

1(2) ASA supports dh-group14-sha1 for SSH. This page lists the rainbow tables we generated and verified to work.

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3.9. Algorithms Used by SSH

Table 3-4 through Table 3-6 summarizethe available ciphers in the SSH protocols andtheir implementations. Required algorithms are in bold;, recommendedones are italic; the others are optional. Parentheses indicate analgorithm not defined in the protocol, but provided in someimplementation. The meanings of the entries are:
x
The implementation supports the algorithm and is included in thedefault build.
o
The implementation supports the algorithm, but it isn'tincluded in the default build (it must be specifically enabled whencompiling).
-
The implementation doesn't support the algorithm.

Table 3-4. Algorithms in the SSH Protocols

SSH-1.5SSH-2.0
Public-keyRSADSA, DH
HashMD5, CRC-32SHA-1, MD5
Symmetric3DES, IDEA,ARCFOUR, DES3DES, Blowfish,Twofish, CAST-128, IDEA, ARCFOUR
Compressionzlibzlib

Note that Table 3-4 simply lists algorithms in differentcategories used in the two protocol specifications, without regard topurpose. So for example, SSH-1 uses both MD5 and CRC-32, but fordifferent purposes; this listing doesn't imply that SSH-1 hasoption to employ MD5 for integrity checking.

Table 3-5. SSH-1 Ciphers

3DESIDEARC4DES(Blowfish)
SSH1xxoox
OpenSSHx---x

Table 3-6. SSH-2 Ciphers

3DESBlowfishTwofishCAST-128IDEARC4
SSH2xxx--x
F-Secure SSH2xxxx-x
OpenSSHxx-x-x
The free version of SSH2 supports only the required DSA for publickeys, while the commercial F-Secure SSH2 Server adds partial supportfor RSA keys for user authentication. [Section 6.2.2, 'Generating RSA/DSA Keys for SSH2'].The F-Secure server starts if its host key is RSA and reports that itsuccessfully read the key. However, it still advertises its host keytype as DSA in its key-exchange messages and then supplies the RSAkey anyway, causing clients to fail when they try to read thesupplied key. Of course, this problem masks the question of whetherthe client can handle an RSA host key even if it were properlyidentified. OpenSSH/2 doesn't contain RSA support at all, butnow that the RSA patent has expired, the ssh-rsa key type will beadded to the SSH-2 protocol, and support should follow shortly.We now summarize each of the algorithms we have mentioned.Don't treat these summaries as complete analyses, however. Youcan't necessarily extrapolate from characteristics ofindividual algorithms (positive or negative) to whole systems withoutconsidering the other parts. Security is complicated that way.

3.9.1. Public-Key Algorithms

3.9.1.1. Rivest-Shamir-Adleman (RSA)

TheRivest-Shamir-Adlemanpublic-key algorithm (RSA) is the most widely used asymmetric cipher.It derives its security from the difficulty of factoring largeintegers that are the product of two large primes of roughly equalsize. Factoring is widely believed to be intractable (i.e.,infeasible, admitting no efficient, polynomial-time solution),although this isn't proven. RSA can be used for both encryptionand signatures.Until September 2000, RSA was claimed to be patented in the United States by PublicKey Partners, Inc., a company in which RSA Security, Inc. is apartner. (The algorithm is now in the public domain.) While thepatent was in force, PKP claimed that it controlled the use of theRSA algorithm in the USA, and that the use of unauthorizedimplementations was illegal. Until the mid-1990s, RSA Securityprovided a freely available reference implementation, RSAref, with alicense allowing educational and broad commercial use (as long as thesoftware itself was not sold for profit). They no longer support ordistribute this toolkit, though it is commonly available. Since RSAis now in the public domain, there's no longer any reason touse RSAref. It is no longer supported, some versions contain securityflaws, and there are better implementations out there; we discourageits use.The SSH-1 protocol specifies use of RSA explicitly. SSH-2 can usemultiple public-key algorithms, but it defines only DSA. [Section 3.9.1.2, 'Digital Signature Algorithm (DSA)'] The SECSH working group plans to add the RSAalgorithm to SSH-2 now that the patent has expired. In the meantime,only the F-Secure SSH2 Server implements RSA keys in SSH2, using theglobal key-format identifier 'ssh-rsa'. This isn'tyet part of the draft standard: to be technically correct it shoulduse a localized name, e.g., [email protected].[Section 3.5.1.1, 'Algorithm choice and negotiation'] However, this is unlikely to cause areal problem. The feature is useful for authentication to an SSH2server with an existing SSH1 key, so you don't need to generatea new (DSA) key.

3.9.1.2. Digital Signature Algorithm (DSA)

The Digital Signature Algorithm (DSA)was developed by the U.S. National Security Agency (NSA), andpromulgated by the U.S. National Institute of Standards andTechnology (NIST) as part of the Digital Signature Standard(DSS). The DSS was issued as aFederal Information Processing Standard, FIPS-186, in May 1994. It isa public-key algorithm, based on the Schnorr and ElGamal methods, andrelies on the difficulty of computing discrete logarithms in a finitefield. It is designed as a signature-only scheme that can't beused for encryption, although a fully general implementation mayeasily perform both RSA and ElGamal encryption.DSA has also been surrounded by a swirl of controversy since itsinception. The NIST first claimed that it had designed DSA, theneventually revealed that the NSA had done so. Many question themotives and ethics of the NSA, with ample historical reason to doso.[37] Researcher Gus Simmons discovered asubliminal channel in DSA that allows an implementor to leakinformation -- for instance, secret key bits -- with everysignature.[38] Since the algorithm wasto be made available as a closed hardware implementation in smartcards as part of the government's Capstone program, many peopleconsidered this property highly suspicious. Finally, NIST intendedDSA to be available royalty-free to all users. To that end it waspatented by David Kravitz (patent #5,231,668), then an employee ofthe NSA, who assigned the patent to the U.S. government. There havebeen claims, however, that DSA infringes existing cryptographicpatents, including the Schnorr patent. To our knowledge, this issuehas yet to be settled in court.
[37]See James Bamford's book, ThePuzzle Palace (Penguin), for an investigative history ofthe NSA.
[38]G. J. Simmons, 'The SubliminalChannels in the U.S. Digital Signature Algorithm (DSA).'Proceedings of the Third Symposium on: State and Progressof Research in Cryptography, Rome: Fondazione UgoBordoni, 1993, pp. 35-54.
The SSH-2 protocol uses DSA as its required (and currently, onlydefined) public-key algorithm for host identification.

3.9.2. Secret-Key Algorithms

3.9.2.1. International Data Encryption Algorithm (IDEA)

TheInternationalData Encryption Algorithm (IDEA) was designed in 1990 by Xuejia Laiand James Massey,[39] and went through several revisions, improvements, andrenamings before reaching its current form. Although relatively new,it is considered secure; the well-known cryptographer Bruce Schneierin 1996 pronounced it 'the best and most secure block algorithmavailable to the public at this time.'
[39]X. Lai and J. Massey, 'AProposal for a New Block Encryption Standard,'Advances in Cryptology -- EUROCRYPT `92Proceedings, Springer-Verlag, 1992, pp 389-404.
IDEA is patented in Europe and the United States by the Swiss companyAscom-Tech AG.[40] The name 'IDEA' is atrademark of Ascom-Tech. The attitude of Ascom-Tech towards thispatent and the use of IDEA in the United States has changed overtime, especially with regard to its inclusion in PGP. It is free fornoncommercial use. Government or commercial use may require aroyalty, where 'commercial use' includes use of thealgorithm internal to a commercial organization, not just directlyselling an implementation or offering its use for profit. Here aretwo sites for more information:
[40]U.S. patent #5,214,703, 25 May 1993;international patent PCT/CH91/00117, 28 November 1991; Europeanpatent EP482 154 B1.
http://www.ascom.ch/infosec/idea.htmlhttp://www.it-sec.com/index_e.php

3.9.2.3. Triple-DES

Triple-DES,or 3DES, is a variant of DES intended to increase its security byincreasing the key length. It has been proven that the DES functiondoesn't form a group over its keys,[41] which means that encrypting multiple times withindependent keys can increase security. 3DES encrypts the plaintextwith three iterations of the DES algorithm, using three separatekeys. The effective key length of 3DES is 112 bits, a vastimprovement over the 56-bit key of plain DES.
[41]K. W.Campbell and M. J. Wiener, 'DES Is Not a Group,'Advances in Cryptology -- CRYPTO `92Proceedings, Springer-Verlag, pp. 512-520.

3.9.2.5. Blowfish

Blowfishwas designed by Bruce Schneier in 1993, as a step toward replacingthe aging DES. It is much faster than DES and IDEA, though not asfast as ARCFOUR, and is unpatented and free for all uses. It isintended specifically for implementation on large, modern,general-purpose microprocessors and for situations with relativelyfew key changes. It isn't particularly suited to low-endenvironments such as smart cards. It employs a variable-sized key of32 to 448 bits; SSH-2 uses 128-bit keys. Blowfish has received a fairamount of cryptanalytic scrutiny and has proved impervious to attackso far. Information is available from Counterpane, Schneier'ssecurity consulting company, at:
http://www.counterpane.com/blowfish.html

3.9.2.6. Twofish

Twofish isanother design by Bruce Schneier, together with J. Kelsey, D.Whiting, D. Wagner, C. Hall, and N. Ferguson. It was submitted in1998 to the NIST as a candidate for the Advanced Encryption Standard,to replace DES as the U.S. government's symmetric dataencryption standard. Two years later, it is one of the five finalistsin the AES selection process, out of 15 initial submissions. LikeBlowfish, it is unpatented and free for all uses, and Counterpane hasprovided uncopyrighted reference implementations, also freely usable.Twofish admits keys of lengths 128, 192, or 256 bits; SSH-2 specifies256-bit keys. Twofish is designed to be more flexible than Blowfish,allowing good implementation in a larger variety of computingenvironments (e.g., slower processors, small memory, in-hardware). Itis very fast, its design is conservative, and it is likely to bequite strong. You can read more about Twofish at:
http://www.counterpane.com/twofish.html
You can read more about the NIST AES program at:
http://www.nist.gov/aes/

3.9.2.8. Speed comparisons

We ran some simple experiments torank the bulk ciphers in order of speed. Since there is no single SSHpackage that contains all of the ciphers, we present two experimentsto cover them all. Table 3-7 and Table 3-8 show the time required totransfer a 5-MB file from a 300-MHz Linux box to a 100-MHz Sparc-20over an otherwise unloaded 10-base-T Ethernet.

Table 3-7. Transferring with scp2 (F-Secure SSH2 2.0.13)

CipherTransfer Time (seconds)Throughput (KB/second)
RC422.5227.4
Blowfish24.5208.6
CAST-12826.4193.9
Twofish28.2181.3
3DES51.898.8

Table 3-8. Same Test with scp1 (SSH-1.2.27)

CipherTransfer Time (seconds)Throughput (KB/second)
RC451024.0
Blowfish6853.3
CAST-1287731.4
Twofish14365.7
3DES15341.3
Note that scp1 is roughly four times faster thanscp2. This is due to a major implementationdifference: scp1 uses the scp1-t server, whereas scp2uses the SFTP subsystem. [Section 7.5.9, 'For Internal Use Only'] Nonetheless,the relative cipher speed comparisons do agree where they overlap.We must emphasize that we included RC4 in the SSH1 test only forcompleteness; due to security vulnerabilities, RC4 shouldn'tordinarily be used with the SSH-1 protocol.

3.9.3. Hash Functions

3.9.3.1. CRC-32

The 32-bit Cyclic RedundancyCheck (CRC-32), defined in ISO 3309,[42] is a noncryptographic hashfunction for detecting accidental changes to data. The SSH-1 protocoluses CRC-32 (with the polynomial 0xEDB88320) for integrity checking,and this weakness admits the 'insertion attack' discussedlater. [Section 3.10.5, 'The Insertion Attack'] The SSH-2 protocol employscryptographically strong hash functions for integrity checking,obviating this attack.
[42]InternationalOrganization for Standardization, ISO InformationProcessing Systems -- Data Communication High-Level Data LinkControl Procedure -- Frame Structure, IS 3309, October1984, 3rd Edition.

3.9.3.2. MD5

MD5 ('Message Digest algorithm number5') is a cryptographically strong, 128-bit hash algorithmdesigned by Ron Rivest in 1991, one of a series he designed forRSADSI (MD2 through MD5). MD5 is unpatented, placed in the publicdomain by RSADSI, and documented in RFC-1321. It has been a standardhash algorithm for several years, used in many cryptographic productsand standards. A successful collision attack against the MD5compression function by den Boer and Bosselaers in 1993 caused someconcern, and though the attack hasn't resulted in any practicalweaknesses, there is an expectation that it will, and people arebeginning to avoid MD5 in favor of newer algorithms. RSADSIthemselves recommend moving away from MD5 in favor of SHA-1 orRIPEMD-160 for future applications demandingcollision-resistance.[43]
[43]RSA Laboratories Bulletin #4,12 November 1996, ftp://ftp.rsasecurity.com/pub/pdfs/bulletn4.pdf.

3.9.3.4. RIPEMD-160

Yet another 160-bit MD4 variant,RIPEMD-160, wasdeveloped by Hans Dobbertin, Antoon Bosselaers, and Bart Preneel aspart of the European Community RIPE project. RIPE stands for RACEIntegrity Primitives Evaluation;[44]RACE, in turn, was the program for Research and Development inAdvanced Communications Technologies in Europe, an EC-sponsoredprogram which ran from June 1987 to December 1995 (http://www.analysys.com). RIPEwas part of the RACE effort, devoted to studying and developing dataintegrity techniques. Hence, RIPEMD-160 should be read as 'theRIPE Message Digest (160 bits).' Inparticular, it has nothing to do with RIPEM, an old Privacy-EnhancedMail (PEM) implementation by Mark Riordan (http://ripem.msu.edu/ ).
[44]Not to be confusedwith another 'RIPE,' Réseaux IP Européens('European IP Networks'), a technical and coordinatingassociation of entities operating wide area IP networks in Europe andelsewhere (http://www.ripe.net).
RIPEMD-160 isn't defined in the SSH protocol, but it is usedfor an implementation-specific MAC algorithm in OpenSSH, under thename [email protected]. RIPEMD-160 isunpatented and free for all uses. You can read more about itat:
http://www.esat.kuleuven.ac.be/~bosselae/ripemd160.html

3.9.4. Compression Algorithms: zlib

zlib is currently the only compression algorithm defined for SSH. Inthe SSH protocol documents, the term 'zlib' refers to the'deflate' lossless compression algorithm as firstimplemented in the popular gzip compressionutility, and later documented in RFC-1951. It is available as asoftware library called ZLIB at:
http://www.info-zip.org/pub/infozip/zlib/
3.8. SSH and File Transfers 3.10. Threats SSH Can Counter

Copyright © 2002 O'Reilly & Associates. All rights reserved.





У нас есть два сервера CentOS 6.9. Один мы назовем «INHOUSE», а другой назовем «BACKUP».

Мы пытаемся настроить скрипт, который использует соединение RSA, где мы можем использовать SSH от сервера «INHOUSE» к серверу «BACKUP».

Это то, что мы делали в прошлом, но этот случай вызывает у нас проблемы. После копирования ключа RSA из «INHOUSE» в «BACKUP» (и перезапуска службы SSHD) мы можем перевести SSH в «BACKUP», однако нам все равно предлагается пароль.

Ssh sha1 fingerprint

Я знаю, что здесь есть объяснение, но у нас это не сработало.

Sha1

Мы попытались уничтожить содержимое authorized_keys файла на «BACKUP» и повторного добавления ключей и она по- прежнему не работает.

Я знаю, что иногда разрешения могут быть проблемой. Вот мои текущие настройки разрешений:

На «BACKUP» в /root/:

В /root/.ssh:

На «BACKUP» в /root/:

В /root/.ssh на «BACKUP»:

Также вот как мы установили /etc/ssh/sshd_config на каждом сервере.

На «BACKUP»: (все значения по умолчанию)

На «INHOUSE»: (RSAAuth является единственным не по умолчанию)

Ssh Sha1

Мы также попытались установить противоположное направление. Мы можем SSH из «BACKUP» в «INHOUSE».

Вывод команды ssh -vvv показывает следующее; Что еще я могу попытаться сделать так, чтобы SSH работал от «INHOUSE» до «BACKUP» без запроса пароля?

Ваш каталог .ssh и его содержимое должны быть доступны только владельцу. У них не должно быть никаких групповых или глобальных разрешений.

Сервер:

Клиент:

Ваш .ssh/ в обеих системах имеет неправильные разрешения. У тебя есть

Sha1

Kexalgorithms Diffie Hellman Group1 Sha1

Это должен быть drwx------ . Запустите эту команду, чтобы изменить эти разрешения для этих каталогов:

No Matching Key Exchange Algorithm

И аналогично разрешениям .ssh , у вас есть это для authorized_keys:

-rwx ------ 1 root root 394 сен. 18 10:54 авторизованных ключей

Это должно быть -rw------- . Запустите эту команду, чтобы изменить эти разрешения:

Эти команды, начинающиеся с ~/ предполагают, что вы вошли в систему как пользователь, имеющий доступ к этому каталогу .ssh . Так что отрегулируйте путь в соответствии со своими потребностями.

Ssh

Ssh Hmac-sha1

Кроме того, если вы хотите SSH из «INHOUSE» в «BACKUP», вам нужно отредактировать /etc/ssh/sshd_config чтобы RSAAuthentication yes и перезапускал SSHD. Скорее всего, это причина, по которой вы можете использовать SSH с «BACKUP» на «INHOUSE», но не с «INHOUSE» на «BACKUP» на данный момент.

Ssh Sha1 Group1

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