📄 draft-ietf-secsh-architecture-15.2.ps
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90 rotate0.706651 dup scaleuserdict/PStoPSmatrix matrix currentmatrix putuserdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip/showpage{}def/copypage{}def/erasepage{}defPStoPSxform concat%%BeginPageSetup_S75 0 translate/pagenum 1 def/fname () def/fdir () def/ftail () def/user_header_p false def%%EndPageSetup5 701 M(Network Working Group T. Ylonen) s5 690 M(Internet-Draft SSH Communications Security Corp) s5 679 M(Expires: March 31, 2004 D. Moffat, Ed.) s5 668 M( Sun Microsystems, Inc) s5 657 M( Oct 2003) s5 624 M( SSH Protocol Architecture) s5 613 M( draft-ietf-secsh-architecture-15.txt) s5 591 M(Status of this Memo) s5 569 M( This document is an Internet-Draft and is in full conformance with) s5 558 M( all provisions of Section 10 of RFC2026.) s5 536 M( Internet-Drafts are working documents of the Internet Engineering) s5 525 M( Task Force \(IETF\), its areas, and its working groups. Note that other) s5 514 M( groups may also distribute working documents as Internet-Drafts.) s5 492 M( Internet-Drafts are draft documents valid for a maximum of six months) s5 481 M( and may be updated, replaced, or obsoleted by other documents at any) s5 470 M( time. It is inappropriate to use Internet-Drafts as reference) s5 459 M( material or to cite them other than as "work in progress.") s5 437 M( The list of current Internet-Drafts can be accessed at http://) s5 426 M( www.ietf.org/ietf/1id-abstracts.txt.) s5 404 M( The list of Internet-Draft Shadow Directories can be accessed at) s5 393 M( http://www.ietf.org/shadow.html.) s5 371 M( This Internet-Draft will expire on March 31, 2004.) s5 349 M(Copyright Notice) s5 327 M( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s5 305 M(Abstract) s5 283 M( SSH is a protocol for secure remote login and other secure network) s5 272 M( services over an insecure network. This document describes the) s5 261 M( architecture of the SSH protocol, as well as the notation and) s5 250 M( terminology used in SSH protocol documents. It also discusses the SSH) s5 239 M( algorithm naming system that allows local extensions. The SSH) s5 228 M( protocol consists of three major components: The Transport Layer) s5 217 M( Protocol provides server authentication, confidentiality, and) s5 206 M( integrity with perfect forward secrecy. The User Authentication) s5 195 M( Protocol authenticates the client to the server. The Connection) s5 184 M( Protocol multiplexes the encrypted tunnel into several logical) s5 173 M( channels. Details of these protocols are described in separate) s5 129 M(Ylonen & Moffat Expires March 31, 2004 [Page 1]) s_RSPStoPSsaved restoreuserdict/PStoPSsaved save putPStoPSmatrix setmatrix595.000000 421.271378 translate90 rotate0.706651 dup scaleuserdict/PStoPSmatrix matrix currentmatrix putuserdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclipPStoPSxform concat%%BeginPageSetup_S75 0 translate/pagenum 2 def/fname () def/fdir () def/ftail () def/user_header_p false def%%EndPageSetup5 723 M(Internet-Draft SSH Protocol Architecture Oct 2003) s5 690 M( documents.) s5 668 M(Table of Contents) s5 646 M( 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3) s5 635 M( 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3) s5 624 M( 3. Specification of Requirements . . . . . . . . . . . . . . . 3) s5 613 M( 4. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 3) s5 602 M( 4.1 Host Keys . . . . . . . . . . . . . . . . . . . . . . . . . 4) s5 591 M( 4.2 Extensibility . . . . . . . . . . . . . . . . . . . . . . . 5) s5 580 M( 4.3 Policy Issues . . . . . . . . . . . . . . . . . . . . . . . 5) s5 569 M( 4.4 Security Properties . . . . . . . . . . . . . . . . . . . . 6) s5 558 M( 4.5 Packet Size and Overhead . . . . . . . . . . . . . . . . . . 6) s5 547 M( 4.6 Localization and Character Set Support . . . . . . . . . . . 7) s5 536 M( 5. Data Type Representations Used in the SSH Protocols . . . . 8) s5 525 M( 6. Algorithm Naming . . . . . . . . . . . . . . . . . . . . . . 10) s5 514 M( 7. Message Numbers . . . . . . . . . . . . . . . . . . . . . . 11) s5 503 M( 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 11) s5 492 M( 9. Security Considerations . . . . . . . . . . . . . . . . . . 12) s5 481 M( 9.1 Pseudo-Random Number Generation . . . . . . . . . . . . . . 12) s5 470 M( 9.2 Transport . . . . . . . . . . . . . . . . . . . . . . . . . 13) s5 459 M( 9.2.1 Confidentiality . . . . . . . . . . . . . . . . . . . . . . 13) s5 448 M( 9.2.2 Data Integrity . . . . . . . . . . . . . . . . . . . . . . . 16) s5 437 M( 9.2.3 Replay . . . . . . . . . . . . . . . . . . . . . . . . . . . 16) s5 426 M( 9.2.4 Man-in-the-middle . . . . . . . . . . . . . . . . . . . . . 17) s5 415 M( 9.2.5 Denial-of-service . . . . . . . . . . . . . . . . . . . . . 19) s5 404 M( 9.2.6 Covert Channels . . . . . . . . . . . . . . . . . . . . . . 19) s5 393 M( 9.2.7 Forward Secrecy . . . . . . . . . . . . . . . . . . . . . . 20) s5 382 M( 9.3 Authentication Protocol . . . . . . . . . . . . . . . . . . 20) s5 371 M( 9.3.1 Weak Transport . . . . . . . . . . . . . . . . . . . . . . . 21) s5 360 M( 9.3.2 Debug messages . . . . . . . . . . . . . . . . . . . . . . . 21) s5 349 M( 9.3.3 Local security policy . . . . . . . . . . . . . . . . . . . 21) s5 338 M( 9.3.4 Public key authentication . . . . . . . . . . . . . . . . . 22) s5 327 M( 9.3.5 Password authentication . . . . . . . . . . . . . . . . . . 22) s5 316 M( 9.3.6 Host based authentication . . . . . . . . . . . . . . . . . 23) s5 305 M( 9.4 Connection protocol . . . . . . . . . . . . . . . . . . . . 23) s5 294 M( 9.4.1 End point security . . . . . . . . . . . . . . . . . . . . . 23) s5 283 M( 9.4.2 Proxy forwarding . . . . . . . . . . . . . . . . . . . . . . 23) s5 272 M( 9.4.3 X11 forwarding . . . . . . . . . . . . . . . . . . . . . . . 24) s5 261 M( Normative References . . . . . . . . . . . . . . . . . . . . 24) s5 250 M( Informative References . . . . . . . . . . . . . . . . . . . 25) s5 239 M( Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 27) s5 228 M( Intellectual Property and Copyright Statements . . . . . . . 28) s5 129 M(Ylonen & Moffat Expires March 31, 2004 [Page 2]) s_RSPStoPSsaved restore%%Page: (2,3) 2userdict/PStoPSsaved save putPStoPSmatrix setmatrix595.000000 0.271378 translate90 rotate0.706651 dup scaleuserdict/PStoPSmatrix matrix currentmatrix putuserdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip/showpage{}def/copypage{}def/erasepage{}defPStoPSxform concat%%BeginPageSetup_S75 0 translate/pagenum 3 def/fname () def/fdir () def/ftail () def/user_header_p false def%%EndPageSetup5 723 M(Internet-Draft SSH Protocol Architecture Oct 2003) s5 690 M(1. Contributors) s5 668 M( The major original contributors of this document were: Tatu Ylonen,) s5 657 M( Tero Kivinen, Timo J. Rinne, Sami Lehtinen \(all of SSH Communications) s5 646 M( Security Corp\), and Markku-Juhani O. Saarinen \(University of) s5 635 M( Jyvaskyla\)) s5 613 M( The document editor is: Darren.Moffat@Sun.COM. Comments on this) s5 602 M( internet draft should be sent to the IETF SECSH working group,) s5 591 M( details at: http://ietf.org/html.charters/secsh-charter.html) s5 569 M(2. Introduction) s5 547 M( SSH is a protocol for secure remote login and other secure network) s5 536 M( services over an insecure network. It consists of three major) s5 525 M( components:) s5 514 M( o The Transport Layer Protocol [SSH-TRANS] provides server) s5 503 M( authentication, confidentiality, and integrity. It may optionally) s5 492 M( also provide compression. The transport layer will typically be) s5 481 M( run over a TCP/IP connection, but might also be used on top of any) s5 470 M( other reliable data stream.) s5 459 M( o The User Authentication Protocol [SSH-USERAUTH] authenticates the) s5 448 M( client-side user to the server. It runs over the transport layer) s5 437 M( protocol.) s5 426 M( o The Connection Protocol [SSH-CONNECT] multiplexes the encrypted) s5 415 M( tunnel into several logical channels. It runs over the user) s5 404 M( authentication protocol.) s5 382 M( The client sends a service request once a secure transport layer) s5 371 M( connection has been established. A second service request is sent) s5 360 M( after user authentication is complete. This allows new protocols to) s5 349 M( be defined and coexist with the protocols listed above.) s5 327 M( The connection protocol provides channels that can be used for a wide) s5 316 M( range of purposes. Standard methods are provided for setting up) s5 305 M( secure interactive shell sessions and for forwarding \("tunneling"\)) s5 294 M( arbitrary TCP/IP ports and X11 connections.) s5 272 M(3. Specification of Requirements) s5 250 M( All documents related to the SSH protocols shall use the keywords) s5 239 M( "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",) s5 228 M( "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" to describe) s5 217 M( requirements. They are to be interpreted as described in [RFC2119].) s5 195 M(4. Architecture) s5 129 M(Ylonen & Moffat Expires March 31, 2004 [Page 3]) s_RSPStoPSsaved restoreuserdict/PStoPSsaved save putPStoPSmatrix setmatrix595.000000 421.271378 translate90 rotate0.706651 dup scaleuserdict/PStoPSmatrix matrix currentmatrix putuserdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclipPStoPSxform concat%%BeginPageSetup_S75 0 translate/pagenum 4 def/fname () def/fdir () def/ftail () def/user_header_p false def%%EndPageSetup5 723 M(Internet-Draft SSH Protocol Architecture Oct 2003) s5 690 M(4.1 Host Keys) s5 668 M( Each server host SHOULD have a host key. Hosts MAY have multiple) s5 657 M( host keys using multiple different algorithms. Multiple hosts MAY) s5 646 M( share the same host key. If a host has keys at all, it MUST have at) s5 635 M( least one key using each REQUIRED public key algorithm \(DSS) s5 624 M( [FIPS-186]\).) s5 602 M( The server host key is used during key exchange to verify that the) s5 591 M( client is really talking to the correct server. For this to be) s5 580 M( possible, the client must have a priori knowledge of the server's) s5 569 M( public host key.) s5 547 M( Two different trust models can be used:) s5 536 M( o The client has a local database that associates each host name \(as) s5 525 M( typed by the user\) with the corresponding public host key. This) s5 514 M( method requires no centrally administered infrastructure, and no) s5 503 M( third-party coordination. The downside is that the database of) s5 492 M( name-to-key associations may become burdensome to maintain.) s5 481 M( o The host name-to-key association is certified by some trusted) s5 470 M( certification authority. The client only knows the CA root key,) s5 459 M( and can verify the validity of all host keys certified by accepted) s5 448 M( CAs.) s5 426 M( The second alternative eases the maintenance problem, since) s5 415 M( ideally only a single CA key needs to be securely stored on the) s5 404 M( client. On the other hand, each host key must be appropriately) s5 393 M( certified by a central authority before authorization is possible.) s5 382 M( Also, a lot of trust is placed on the central infrastructure.) s5 360 M( The protocol provides the option that the server name - host key) s5 349 M( association is not checked when connecting to the host for the first) s5 338 M( time. This allows communication without prior communication of host) s5 327 M( keys or certification. The connection still provides protection) s5 316 M( against passive listening; however, it becomes vulnerable to active) s5 305 M( man-in-the-middle attacks. Implementations SHOULD NOT normally allow) s5 294 M( such connections by default, as they pose a potential security) s5 283 M( problem. However, as there is no widely deployed key infrastructure) s5 272 M( available on the Internet yet, this option makes the protocol much) s5 261 M( more usable during the transition time until such an infrastructure) s5 250 M( emerges, while still providing a much higher level of security than) s5 239 M( that offered by older solutions \(e.g. telnet [RFC-854] and rlogin) s5 228 M( [RFC-1282]\).) s5 206 M( Implementations SHOULD try to make the best effort to check host) s5 195 M( keys. An example of a possible strategy is to only accept a host key) s5 184 M( without checking the first time a host is connected, save the key in) s5 173 M( a local database, and compare against that key on all future) s⌨️ 快捷键说明
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