Generated by Python Test Suite | Date: Mon May 4 14:02:28 2026 | Debug Log
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ip/host
port(range)
ping
IPv6
iperf3 -c (TCP)
--reverse (TCP)
iperf3 -c (UDP)
--reverse (UDP)
Congestion ⓘ
Select a server to view details
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Test Explanations
1. Port Range & Scanning
This test verifies which ports are accessible on the target server. We use RustScan (via Docker) to quickly scan for open ports.
Why it fails/varies: A "Closed" result doesn't always mean the service is down. Many servers use firewalls that drop scan packets (stealth mode) or only allow traffic from specific IPs. Additionally, some network policies block the scanning behavior itself.
2. Ping (ICMP)
Ping measures the round-trip time (RTT) for a packet to reach the server and return.
Usage: It gives a quick estimate of network latency.
Reliability: Ping uses ICMP packets. Many modern servers and routers deprioritize or block ICMP to prevent flood attacks. Therefore, a "Timeout" or failure here does not prove the server is offline; it just means it's not replying to pings.
3. Server Busy
Receiving the "server busy" message confirms that the server is online and reachable, but the port is currently occupied by another test.
Unlike multi-port configurations, single-port iperf3 servers often reject connections because they lack concurrency, not because they are down.
4. IPv6 Connectivity
Tests connectivity using the IPv6 protocol via iperf3 -6 -c <host>.
If the server or your local network doesn't support IPv6, this test will be skipped or marked as failed.
5. iperf3 Modes (TCP/UDP)
iperf3 -c (TCP Upload): Sends data from your machine to the server. Tests your upload speed / server's download speed.
--reverse (TCP Download): The server sends data to your machine. Tests your download speed / server's upload speed.
UDP: Uses User Datagram Protocol. Unlike TCP, it doesn't verify delivery. Used to test packet loss and jitter at a specific target bandwidth.
6. Congestion Control
Congestion Control algorithms manage how TCP sends data to avoid clogging the network.
CUBIC: The standard algorithm. Loss-based - it slows down when packets are lost. Reliable and fair.
BBR (Bottleneck Bandwidth and RTT): Developed by Google. It models the network speed and latency instead of relying on packet loss. It is often faster on long-distance or slightly lossy connections.
Illinois / HTCP: Older algorithms optimized for high-speed, high-latency networks. They try to be more aggressive than standard TCP but are often outperformed by BBR today.
7. Symbols
Success / Passed: The test completed successfully.
Failed: The test failed.
Server Busy: The server is online but currently busy running a test.
Skipped (no IPv6): IPv6 tests are skipped when the server does not support IPv6.
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Not Requested / Unknown: The test was not requested (e.g. UDP was not enabled) or no data is available.