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Origami74andJohnathan Corgan
852f561fa0
Add dual-approach MTU handling to prevent TCP connections from hanging when packets exceed the transport MTU after FIPS encapsulation. ICMPv6 Packet Too Big: - Generate RFC 4443 PTB messages for oversized packets at TUN outbound - Inject back via TUN for local delivery to the application - Per-source rate limiting (100ms interval, 10s entry expiry) - MTU check in handle_tun_outbound before session encapsulation TCP MSS Clamping: - Intercept SYN packets in run_tun_reader() (outbound) - Intercept SYN-ACK packets in TunWriter (inbound) - Clamp MSS option to fit within effective MTU (transport - 127 overhead) - Recalculate TCP checksum after modification Code organization: - ICMP, TCP MSS, and rate limiter modules in upper/ alongside existing protocol-specific packet handling (dns.rs, tun.rs) - Shared FIPS_OVERHEAD constant (127 bytes) and effective_ipv6_mtu() function in upper/icmp.rs - Node::effective_ipv6_mtu() delegates to the shared function - run_tun_reader() accepts actual transport MTU from config Example config corrections: - UDP transport MTU set to 1472 across all configs (correct max UDP payload for standard Ethernet: 1500 - 20 IPv4 - 8 UDP) - Startup logging of effective MTU and max MSS values
38 lines
852 B
YAML
38 lines
852 B
YAML
# FIPS Node A configuration (mesh topology)
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#
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# Identity: npub1sjlh2c3x9w7kjsqg2ay080n2lff2uvt325vpan33ke34rn8l5jcqawh57m
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# FIPS address: fd69:e08d:65cc:3a6b:9c2c:2ac4:bd40:5e4b
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node:
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identity:
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nsec: "0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f20"
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tun:
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enabled: true
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name: fips0
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mtu: 1280
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dns:
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enabled: true
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bind_addr: "127.0.0.1"
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port: 53
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transports:
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udp:
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bind_addr: "0.0.0.0:4000"
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mtu: 1472
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peers:
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- npub: "npub1n9lpnv0592cc2ps6nm0ca3qls642vx7yjsv35rkxqzj2vgds52sqgpverl"
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alias: "node-d"
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addresses:
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- transport: udp
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addr: "172.20.0.13:4000"
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connect_policy: auto_connect
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- npub: "npub1wf8akf8lu2zdkjkmwhl75pqvven654mpv4sz2x2tprl5265mgrzq8nhak4"
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alias: "node-e"
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addresses:
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- transport: udp
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addr: "172.20.0.14:4000"
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connect_policy: auto_connect
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