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2025-01-30
A 204 with a body stalls some clients
204 and 304 must not carry a body; one extra byte is a protocol error.
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2025-01-17
Do not judge a disk by a single fio number
Sequential and random differ by orders of magnitude.
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2025-01-04
The convenience and risk of SSH agent forwarding
It forwards the ability to use a key, not the key — but that ability is enough.
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2024-12-22
Replacing if with map in nginx
If is Evil; map is the supported alternative.
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2024-12-09
Should high-traffic services sample logs
Full logging melts disks; sampling must keep every error.
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2024-11-26
Minimal mutual TLS configuration
A client certificate is not a switch; the CA, depth and revocation all matter.
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2024-11-13
What DNS round-robin cannot do
TTL, caching and failure removal are all against it.
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2024-10-31
When files in /tmp actually disappear
systemd-tmpfiles cleans by age, not on reboot.
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2024-10-18
A new kernel installed but not running
The package is on disk; the old kernel is in memory, with its bugs.
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2024-10-05
fstab will not mount after a disk move: the UUID changed
Device names move around; UUIDs move with the disk.
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2024-09-22
Clean up temporary files with trap
Failures skip the cleanup line, and /tmp grows.
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2024-09-09
Oversized request headers and the 400 that follows
Cookies fill the header and nginx refuses.