diff --git a/network/sockopts.go b/network/sockopts.go
index 7d537e4..1b6c32c 100644
--- a/network/sockopts.go
+++ b/network/sockopts.go
@@ -20,7 +20,7 @@ func SetServerSocketOptions(conn net.Conn, bufferSize int) error {
 }
 
 func setCommonSocketOptions(conn *net.TCPConn) error {
-	if err := conn.SetKeepAliveConfig(net.KeepAliveConfig{
+	if err := applyKeepAlive(conn, net.KeepAliveConfig{
 		Enable:   true,
 		Idle:     DefaultKeepAliveIdle,
 		Interval: DefaultKeepAliveInterval,
diff --git a/network/sockopts_keepalive.go b/network/sockopts_keepalive.go
new file mode 100644
index 0000000..0f8cb42
--- /dev/null
+++ b/network/sockopts_keepalive.go
@@ -0,0 +1,11 @@
+//go:build !openbsd
+
+package network
+
+import "net"
+
+// applyKeepAlive enables TCP keepalive on conn and applies the per-socket
+// idle/interval/count tuning from cfg.
+func applyKeepAlive(conn *net.TCPConn, cfg net.KeepAliveConfig) error {
+	return conn.SetKeepAliveConfig(cfg) //nolint: wrapcheck
+}
diff --git a/network/sockopts_keepalive_openbsd.go b/network/sockopts_keepalive_openbsd.go
new file mode 100644
index 0000000..6c12f7d
--- /dev/null
+++ b/network/sockopts_keepalive_openbsd.go
@@ -0,0 +1,20 @@
+package network
+
+import "net"
+
+// applyKeepAlive enables (or disables) TCP keepalive on conn.
+//
+// OpenBSD has no user-settable per-socket TCP keepalive options: TCP_KEEPIDLE,
+// TCP_KEEPINTVL and TCP_KEEPCNT do not exist on OpenBSD, and Go's
+// (*TCPConn).SetKeepAliveConfig therefore returns ENOPROTOOPT ("protocol not
+// available") for any non-negative Idle/Interval/Count value (see
+// src/net/tcpsockopt_openbsd.go in the Go source tree). Calling
+// SetKeepAliveConfig with mtg's defaults (zero values) breaks every accepted
+// listener connection and every outbound dial on OpenBSD.
+//
+// On OpenBSD we only flip SO_KEEPALIVE on or off; the keepalive timing is
+// controlled system-wide via the sysctl knobs net.inet.tcp.keepidle and
+// net.inet.tcp.keepintvl.
+func applyKeepAlive(conn *net.TCPConn, cfg net.KeepAliveConfig) error {
+	return conn.SetKeepAlive(cfg.Enable) //nolint: wrapcheck
+}
diff --git a/network/v2/sockopts.go b/network/v2/sockopts.go
index 933c76f..edbc47a 100644
--- a/network/v2/sockopts.go
+++ b/network/v2/sockopts.go
@@ -6,7 +6,7 @@ import (
 )
 
 func setCommonSocketOptions(conn *net.TCPConn, keepAliveConfig net.KeepAliveConfig) error {
-	if err := conn.SetKeepAliveConfig(keepAliveConfig); err != nil {
+	if err := applyKeepAlive(conn, keepAliveConfig); err != nil {
 		return fmt.Errorf("cannot configure TCP keepalive: %w", err)
 	}
 
diff --git a/network/v2/sockopts_keepalive.go b/network/v2/sockopts_keepalive.go
new file mode 100644
index 0000000..0f8cb42
--- /dev/null
+++ b/network/v2/sockopts_keepalive.go
@@ -0,0 +1,11 @@
+//go:build !openbsd
+
+package network
+
+import "net"
+
+// applyKeepAlive enables TCP keepalive on conn and applies the per-socket
+// idle/interval/count tuning from cfg.
+func applyKeepAlive(conn *net.TCPConn, cfg net.KeepAliveConfig) error {
+	return conn.SetKeepAliveConfig(cfg) //nolint: wrapcheck
+}
diff --git a/network/v2/sockopts_keepalive_openbsd.go b/network/v2/sockopts_keepalive_openbsd.go
new file mode 100644
index 0000000..6c12f7d
--- /dev/null
+++ b/network/v2/sockopts_keepalive_openbsd.go
@@ -0,0 +1,20 @@
+package network
+
+import "net"
+
+// applyKeepAlive enables (or disables) TCP keepalive on conn.
+//
+// OpenBSD has no user-settable per-socket TCP keepalive options: TCP_KEEPIDLE,
+// TCP_KEEPINTVL and TCP_KEEPCNT do not exist on OpenBSD, and Go's
+// (*TCPConn).SetKeepAliveConfig therefore returns ENOPROTOOPT ("protocol not
+// available") for any non-negative Idle/Interval/Count value (see
+// src/net/tcpsockopt_openbsd.go in the Go source tree). Calling
+// SetKeepAliveConfig with mtg's defaults (zero values) breaks every accepted
+// listener connection and every outbound dial on OpenBSD.
+//
+// On OpenBSD we only flip SO_KEEPALIVE on or off; the keepalive timing is
+// controlled system-wide via the sysctl knobs net.inet.tcp.keepidle and
+// net.inet.tcp.keepintvl.
+func applyKeepAlive(conn *net.TCPConn, cfg net.KeepAliveConfig) error {
+	return conn.SetKeepAlive(cfg.Enable) //nolint: wrapcheck
+}