EC
ENETRESET
Linux / POSIXERRORNotableNetworkHIGH confidence

Network Dropped Connection on Reset

Production Risk

Indicates connection was forcefully terminated; implement reconnect logic.

What this means

ENETRESET (errno 102) is returned when the remote host sent a reset (RST) that terminated the connection, or when the network stack reset the connection due to a keep-alive failure.

Why it happens
  1. 1Remote host sent TCP RST during an established connection
  2. 2TCP keep-alive probes failed — remote host unreachable
  3. 3Intermediate firewall reset the connection
How to reproduce

read() on a TCP connection that was reset by the remote peer.

trigger — this will error
trigger — this will error
ssize_t n = read(sockfd, buf, sizeof(buf));
// Returns -1, errno = ENETRESET if network reset the connection

expected output

read: Network dropped connection on reset (ENETRESET)

Fix

Reconnect and retry

WHEN After ENETRESET

Reconnect and retry
if (errno == ENETRESET) {
  close(sockfd);
  sockfd = reconnect_to_server();
}

Why this works

ENETRESET is terminal for the connection; close and reconnect.

Sources
Official documentation ↗

Linux Programmer Manual tcp(7)

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