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25 lines
1.3 KiB
Plaintext
25 lines
1.3 KiB
Plaintext
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The idea is that IPFilter in its current state can already do a simple L4
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round-robin in its NAT rules. However, it does not detect or sense when a
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service and/or host is down. It will continue to send requests to a downed
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service/host.
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However, IPFilter lets us add and remove rules on-the-fly so it should be
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possible to build a daemon that lets you specify "clusters". In each cluster
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you would specify its members/hosts and services. As well as a health-check
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for the service to determine its current state.
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Once a service was deemed "up" we would add a Round-Robin rule to the NAT
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table, and naturally, the reverse once we detect a service as being "down".
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In addition to this, this program can optionally add ipf rules to log for RST
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(reset) packets coming from the members of your clusters. In the situations
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where the software/port goes down, but the host itself is still working, we
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would detect failure instantly. (Since the forwarded connections to the service
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would trigger a RST packet back). If this option is enabled, l4ip spawns the
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"ipmon" command to monitor for the "log" entries given when such a packet is
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detected. l4ip will then mark the service down. This is an add-on feature and
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is strictly not necessary for functional usage. It is currently only supported
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for TCP.
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WWW: http://www.lundman.net/unix/l4ip.php
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