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This document describes the security framework for the "Hubs and Spokes" model in Softwire networks. It includes updates on authentication, encryption, access control, and protection against various attacks.
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Softwire Security Update Shu Yamamoto Carl Williams Florent Parent Hidetoshi Yokota 67 IETF, San Diego
Document Status • Published -01 version • Revised “Hubs and Spokes” security Security description in framework document is added. Modification with comments at Interim Meeting. • Security for Mesh solution is added. • Subject to Framework Document • This work will keep track with the framework document. • This document will change over time subject to change of framework document.
SC Hub & Spokes Security Model (Trusted) AF(i) • Mutual Authentication SHOULD be offered. (optionally one side) PPP Authentication (CHAP) AF(i,j) AF(i) AAA SI PPP/L2TP/UDP/IP Softwire AF(j) Host User’ Home ISP Network CPE Access Network DoS TRUSTED PPP Encryption (ECP) Voluntary Tunnel • Authentication can be turned off when already authenticated by other means.
SC SC Hub & Spokes Security Model (Non-Trusted) AF(i) • Mutual Authentication MUST be used. • PPP Authentication: no per-packet authentication, integrity nor replay protection RFC3193 Service Theft • IPsec authentication MUST be used. Non-TRUSTED L2TPv2, PPP AAA SI Softwire User Host ISP Network Public Facilities DoS Snoop Spoof Replay Modification Deletion Rogue SC MITM BLH PPP Encryption (ECP): No key management
Softwire Authentication Mechanism • PPP Authentication • Mutual authentication using CHAP • No per-packet authentication, no integrity, no replay protection • L2TPv2 Authentication • Optional CHAP-like authentication • Same security verunerability as PPP • IPsec Authentication • MUST be used in non-trusted, public IP network • IKE must be supported. • Selection of Key management mechanism depends on deployment scenario (shared secret, certificate and EAP exchange identity for IKEv2 ) • NAT-traversal in IKE
Control and Data Plane Protection • IPsec can provide the necessary security mechanisms • “Full payload security” on control and data plane when required. • Fornon-trusted network RFC3193: for Confidentiality, ‘Should’ for Control and ‘May’ for Data.
IPv6 SC Applying IPsec in Hub&Spokes Scenario • L2TPv2 and IPsec filter guidelines described in RFC3193 in case where the SC chooses a new IP address/port number: load-balancing • Use RFC3193 IPsec filter details (section 4) • SC and SI must have IPsec security policy filters pre-configured. AAA SI (PPP/L2TPv2/UDP/IPv4) Softwire User ESP (transport mode) Host ISP Network
AF(j) SC IPsec Security Policy example SI (PPP/L2TPv2/UDP/AF(i)) Softwire User ESP (transport mode) src dst Protocol Action --- --- -------- -------- * SC ESP BYPASS * SC IKE BYPASS * SC UDP, src *, dst 1701 PROTECT(ESP,transport) src dst Protocol Action --- --- -------- -------- SI SC ESP BYPASS SI SC IKE BYPASS SI SC UDP, src 1701, dst 1701 PROTECT(ESP,transport) SC SI UDP, src * , dst 1701 PROTECT(ESP,transport)
SC SC Hub & Spokes Non-Authenticated Mode AF(i) Service Theft Non-Authentication Service Non-TRUSTED L2TPv2, PPP SI Softwire User Host ISP Network (Visited) Public Facilities Snoop Spoof Replay Modification Deletion Ingress Filter Rogue SC MITM BLH Anonymous Connection
SC SC SC Hub & Spokes Security Model (Visited) AF(i) ISP Network (Home) AAA Service Theft Host Authentication Roaming Agreement Non-TRUSTED L2TPv2, PPP AAA SI Softwire User Host ISP Network (Visited) Public Facilities Snoop Spoof Replay Modification Deletion Rogue SC MITM BLH
CE CE PE CE P PE CE P PE CE CE P PE P CE CE CE Mesh Security Model AF(i) Static Route or Routing Protocol Attack on Control Plane Route Reflector AF(i) BGP Update AF(i) AF(i) AFBR-2 AF(j) Backbone AF(i) AFBR-1 AF(i) AFBR-N AF(i) AF(i) Attack on Data Plane DoS Intrusion AF(i)
CE CE PE CE P CE PE P PE CE CE P PE P CE CE CE Security Protection TCP MD5 IPsec S-BGP, soBGP, psBGP AF(i) Static Route or Routing Protocol AF(i) Route Reflector BGP Update AF(i) AF(i) AFBR-2 AF(j) Backbone AF(i) AFBR-1 AF(i) AFBR-N AF(i) AF(i) IPsec Static Routing Packet Filtering AF(i)
Softwire Mesh Security Protection • Control Plane Protection • TDP MD5 MUST be supported Peer-peer based authentication Replay protection is not enough No protection for confidentiality • IPsec ESP provide confidentiality as well as integrity and authentication. IKE must be supported for replay protection • S-BGP, soBGP, and psBGP (Byzantine attacks) • Data Plane Protection • IPsec Encapsulation To support replay protection, integrity, and confidentiality ESP, IKE • Access Control Techniques
TCP MD5 and IPsec for MP-BGP UPDATE • TCP MD5 (RFC2385) • Offering Authentication and integrity on a point-to-point basis • Protection from spoofing attacks and connection hijacking • But not for eavesdropping and weak against replay attacks • Lack of an automated key management • IPsec • ESP protocol offers authentication, data integrity, and anti-replay between BGP speakers (i.e. AFBRs) • IKE protocol supported for automated key management • PKI can be used when available. • draft-bellovin-useipsec-05.txt provides guidelines for mandating the use of IPsec.
IPsec Softwire Mesh (Data Plane) • Encapsulation • BGP Tunnel SAFI provides Softwire mesh encapsulation attributes. • IPsec encapsulation is defined in Tunnel SAFI attributes. • IPsec Parameters • ESP (with or without encryption) • Transport/Tunnel Mode • Automated Key Management (IKE phase1 and ID) • Selectors • SPD • Proposed IPsec Tunnel Information TLV is enough? (only IKE identifier)
Next Steps • To work with security liaison for the review of the document. • To continue to track the framework document update.
Comments from Tero Kivinen • 1. Introduction • Needs more explanation • 3.1 H&S deployment Scenario • Something missing in description • 3.3 Softwire Security Threat Scenarios • Add more other protocol • 3.4 Softwire Security Guidelines • Editorial • Need correction of IKE description • 3.5 Guidelines for Usage of Security Protection Mechanism • Need for IKEv2 description
Comments from Tero Kivinen (cont.) • 3. 5.2.3 IPsec Authentication • To address that Group Shared key should not be used. • 3.5.5.1 IPv6 over IPv4 Softwire with L2TPv2 example • Comments on PDS table. Need more work. • 4.1 Deployment Scenarios • Add more words • 4.3 Softwire Threat Scenarios • Need some more explanation • 4.5.1 Security Protection mechanism for Control Plane • TCP MD5 should not be mandated. IPsec Should be.
Comments from Tero Kivinen (cont.) • 4. 5.1.1 TCP MD5 • TCP MD5 does not protect against so security attacks described in the document. Need more proper description for TCP MD5. • 4.5.1.2 IPsec • Use of AH should be dropped. AH does not work for NAT traversal. • Should mention IKEv2 instead of IKEv1 • 4.5.1.3 Secure BGP • Typo