Session Date/Time: 10 Nov 2023 08:30

masque

Summary

The MASQUE working group met at IETF 118 to discuss ongoing work on extensions to the core MASQUE protocol. Key topics included security and privacy considerations for Quick Proxy forwarding mode, a potential loop attack in multi-hop proxy scenarios, and the MASQUE Connect-UDP Listener draft. There was also a discussion about the Connect-Ethernet draft, which sparked debate about its scope, adherence to Ethernet standards, and charter implications.

Key Discussion Points

Quick Proxy Threat Model and Encryption: The design team presented an analysis of passive and active attacks against Quick Proxy's forwarded mode. Discussion focused on the trade-offs between security, privacy, and performance, especially in relation to timing and packet size correlation attacks. The team is leaning toward focusing on mitigation techniques but avoiding complex solutions that emulate tunnel mode. Concern raised regarding the effort required to mitigate timing/size attacks.
Multi-Hop Proxy Loop Attack: Martin Duke presented a potential loop attack in multi-hop proxy deployments where a malicious client could cause traffic to loop indefinitely between proxies due to CID manipulation and lack of TTL decrementing. Several mitigation strategies were discussed, including enforcing a TTL, restricting socket reuse, and altering CID management.
MASQUE Connect-UDP Listener: Abby Singh presented the Connect-UDP Listener draft, which enables clients to listen for connections from multiple targets over a single connection. Discussions centered on renaming the extension, proxy advertisement of its public IP address and port(s), and restricting accessible IPs to mitigate potential abuse. The closing of the main listener was seen as a potential defense.
Connect-Ethernet Draft: Discussion about the scope of the Connect-Ethernet draft and its alignment with Ethernet standards. Concerns were raised about whether the group should be implementing the full range of the specification and its associated attributes and implications. Need to talk to 802 group about if a subset is acceptable. Potential for coordination with IEEE 802 was emphasized. The group agreed to delay re-chartering until this discussion happens. Fragmentation and reassembly of Ethernet frames were also discussed.

Decisions and Action Items

Quick Proxy: Continue analysis of mitigation efforts against timing/size attacks, including padding and traffic shaping for both tunnel and forwarded modes. Investigate alternative encryption protocols based on Tor research.
Multi-Hop Proxy Loop Attack: Further discussion on the list regarding the optimal mitigation strategy for the loop attack, balancing complexity and security. Authors to update the document with best solution.
Connect-UDP Listener: Continue discussion on the mailing list regarding the name of the extension. Implement the agreed-upon design for proxy address advertisement (single IPv4/IPv6 per port). Explore mechanisms for clients to block unwanted traffic sources, potentially leveraging context IDs and capsule negotiation.
Connect-Ethernet: Contact IEEE 802 and other relevant parties to review scope and alignment with standards. Eric Vyncke will take the coordination task. Delay charter update until after liaison with 802.

Next Steps

Authors to incorporate feedback from the meeting into updated drafts.
Continue discussion of open issues on the mailing list and GitHub.
Chairs to facilitate coordination with IEEE 802 regarding the Connect-Ethernet draft.
Chairs to coordinate with other internal IETF areas to review changes.