asmhatreandClaude Sonnet 5.5
fadfd05670
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01KqJyCidz3ZgRyHABv2GVJh
23 lines
1.2 KiB
Bash
Executable File
23 lines
1.2 KiB
Bash
Executable File
#!/usr/bin/env bash
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# loss.sh P drop P percent (may be fractional, e.g. 2.5) of packets in each direction on lo, port 4433, TCP and UDP
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# loss.sh P udp the same, UDP only (100 udp = a firewall that blocks QUIC)
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# loss.sh off remove the rules and restore the loopback MTU
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# Loopback MTU is 65536, so TCP would send 64 KiB segments while QUIC sends ~1.2 KB datagrams; a per-packet drop rate
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# would then be wildly unfair. While loss is on we set the loopback MTU to 1500 so both protocols use Ethernet-sized packets.
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# Kernel-level random drop (iptables -m statistic). This is NOT tc netem (netem was unavailable in the sandbox:
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# "Specified qdisc kind is unknown"), so it adds loss but no delay. Needs root / CAP_NET_ADMIN.
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set -euo pipefail
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CH=H3LOSS
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off() { ip link set dev lo mtu 65536; iptables -D INPUT -i lo -j $CH 2>/dev/null || true; iptables -F $CH 2>/dev/null || true; iptables -X $CH 2>/dev/null || true; }
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off
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[ "${1:?P or off}" = off ] && exit 0
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P=$(python3 -c "print(float('$1')/100)")
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ip link set dev lo mtu 1500
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iptables -N $CH
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for proto in ${2:-tcp udp}; do
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for side in --dport --sport; do
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iptables -A $CH -p $proto $side 4433 -m statistic --mode random --probability "$P" -j DROP
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done
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done
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iptables -A INPUT -i lo -j $CH
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