Initialize ICMP echo ID and sequence to random values #412
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This should help preventing issues with some network devices that have trouble NATing ICMP packets with the same ID and sequence nubmer but a different source IP address. Currently, this can happen if the blackbox_exporter runs in a container (the ID is set to the PID, which is typically 1 in a container), and serveral blackbox_exporters are restarted at the same time (the sequence numbers are reset to zero and stay in sync). This commit sets the ICMP echo ID to a random value if the PID is 1, and initializes the sequence number at a random offset. See prometheus#411 for details. Signed-off-by: Benoît Knecht <benoit.knecht@fsfe.org>
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This should help preventing issues with some network devices that have
trouble NATing ICMP packets with the same ID and sequence nubmer but a
different source IP address.
Currently, this can happen if the blackbox_exporter runs in a container
(the ID is set to the PID, which is typically 1 in a container), and
serveral blackbox_exporters are restarted at the same time (the sequence
numbers are reset to zero and stay in sync).
This commit sets the ICMP echo ID to a random value if the PID is 1, and
initializes the sequence number at a random offset.
See #411 for details.