Fix clw-network-exhausted: Network Resources Exhausted in OpenClaw

By James Park
OpenClaw advanced Linux macOS Windows (WSL2)

1. Symptoms

The clw-network-exhausted error manifests when OpenClaw detects that network resources allocated to containers, services, or the runtime environment have been fully consumed. This typically occurs during high-throughput operations, concurrent service deployments, or when background processes accumulate unbounded network handles.

Shell Output Indicating This Error:

[OpenClaw Runtime Error]
Error Code: clw-network-exhausted
Message: Network resources exhausted. Unable to establish new connections.
Context: Container 'api-service-prod' attempted to bind to port 8080
Details: Available ephemeral ports: 0/65535, Active connections: 8192/8192
Timestamp: 2024-01-15T14:32:07Z
Recommendation: Increase system network limits or terminate idle connections

Additional Symptoms Include:

  • Services failing to start with bind address already in use errors despite no visible processes occupying those ports
  • Timeout errors during API calls to internal container services
  • Increased latency on inter-container communication
  • OpenClaw daemon reporting degraded health status in openclaw status output
  • Kernel log entries showing “too many open files” or network-related syscall failures
  • DNS resolution failures within container networks despite network configuration appearing correct

2. Root Cause

The clw-network-exhausted error stems from depletion of one or more underlying network resource pools that OpenClaw depends upon. Understanding these resource constraints requires examining the layered architecture where application-level networking interfaces with the operating system’s network stack.

Primary Contributing Factors:

The most common cause involves exhausting the ephemeral port range. Linux systems typically reserve ports 32768-60999 for ephemeral (client-side) ports. When a container or service maintains thousands of concurrent outbound connections without proper connection pooling or linger timeouts, these ports become exhausted. Each connection, whether properly closed or left in TIME_WAIT state, consumes a port temporarily until the operating system reclaims it after the appropriate timeout period.

OpenClaw’s container networking subsystem creates virtual ethernet pairs and bridge interfaces for inter-container communication. Each active container connection consumes file descriptors from the system limit. If the global fs.file-max or per-process ulimit -n settings are configured below the workload’s actual requirements, OpenClaw cannot allocate new network handles even when physical bandwidth remains available.

Additionally, network namespace isolation creates independent network stacks for each container. When running numerous containers simultaneously, the aggregated connection count across all namespaces can exceed the host’s connection tracking table size. The nf_conntrack_max kernel parameter limits entries in the connection tracking table, and when full, new valid connections are rejected until entries expire.

Secondary Contributing Factors:

Container bridge network mode requires MAC address allocation per container. While technically not a network resource in the traditional sense, some hypervisor or network monitoring systems impose MAC address limits or require uniqueness that becomes problematic at scale. Rate limiting on network interfaces, whether hardware-enforced or software-configured via tc (traffic control), can also manifest as resource exhaustion when legitimate traffic exceeds configured thresholds.

3. Step-by-Step Fix

Resolving the clw-network-exhausted error requires systematic investigation of which resource pool is depleted, followed by targeted configuration adjustments. Complete these steps in order until the error resolves.

Step 1: Identify the Depleted Resource

# Check current network connection counts
ss -s | grep -E "(TCP|ESTABLISHED|TIME-WAIT)"

# View ephemeral port availability
cat /proc/sys/net/ipv4/ip_local_port_range

# Check file descriptor usage for OpenClaw
lsof -p $(pgrep -f openclaw-daemon) 2>/dev/null | wc -l
ulimit -n

# Examine connection tracking table usage
cat /proc/sys/net/netfilter/nf_conntrack_max
cat /proc/sys/net/netfilter/nf_conntrack_count

Step 2: Increase Ephemeral Port Range

Before:

cat /proc/sys/net/ipv4/ip_local_port_range
# Output: 32768   60999

After:

# Append to /etc/sysctl.conf for persistence
echo "net.ipv4.ip_local_port_range = 32768 65535" | sudo tee -a /etc/sysctl.conf

# Apply immediately
sudo sysctl -w net.ipv4.ip_local_port_range="32768 65535"

Step 3: Raise File Descriptor Limits

Before:

ulimit -n
# Output: 1024

After:

# Add to /etc/security/limits.conf
sudo bash -c 'cat >> /etc/security/limits.conf << EOF
root             soft    nofile          65536
root             hard    nofile          65536
EOF'

# Modify OpenClaw daemon limits in /etc/openclaw/daemon.yml
sudo sed -i 's/max-open-files: 1024/max-open-files: 65536/' /etc/openclaw/daemon.yml

# Restart OpenClaw daemon
sudo systemctl restart openclaw-daemon

Step 4: Increase Connection Tracking Table Size

Before:

cat /proc/sys/net/netfilter/nf_conntrack_max
# Output: 262144

After:

# Append to /etc/sysctl.conf
sudo bash -c 'cat >> /etc/sysctl.conf << EOF
net.netfilter.nf_conntrack_max = 1048576
net.netfilter.nf_conntrack_tcp_timeout_established = 3600
EOF'

# Apply immediately
sudo sysctl -w net.netfilter.nf_conntrack_max=1048576
sudo sysctl -w net.netfilter.nf_conntrack_tcp_timeout_established=3600

Step 5: Configure Connection Reuse in Application Layer

If the error stems from excessive TIME_WAIT connections, enable connection pooling and adjust TCP keepalive parameters:

Before:

# Example openclaw-service.yml
network:
  max_connections: 1000
  connection_timeout: 30s

After:

# Example openclaw-service.yml
network:
  max_connections: 1000
  connection_timeout: 30s
  keepalive: true
  keepalive_idle: 60
  keepalive_interval: 30
  keepalive_count: 3
  reuse_address: true

4. Verification

After applying fixes, verification ensures the resolution is stable and the system handles expected workloads without recurrence.

# Confirm ephemeral port range update
cat /proc/sys/net/ipv4/ip_local_port_range
# Expected: 32768   65535

# Verify file descriptor limits are active
ulimit -n
# Expected: 65536 or higher

# Check OpenClaw daemon is healthy
openclaw status
# Expected: All services operational, no warnings

# Generate test load to verify stability under pressure
openclaw run --load-test --duration 60s ./test-workload.yaml

# Monitor network resource usage during load
watch -n 1 'ss -s | grep -E "(TCP|ESTAB)"'

Expected Successful Output:

[OpenClaw Status]
Version: 2.4.1
Runtime: Healthy
Containers Running: 12
Network Status:
  - Ephemeral Ports Available: 32768-65535 (32768 free)
  - File Descriptors in Use: 4,521 / 65,536
  - Connection Tracking: 12,847 / 1,048,576
  - Active TCP Connections: 4,521

Load Test Result: PASSED
  - Peak Concurrent Connections: 8,234
  - Failed Connection Attempts: 0
  - Average Latency: 12ms

If the load test passes without triggering clw-network-exhausted, the fix is confirmed. Monitor logs over 24-48 hours under production traffic to ensure no resource creep causes recurrence.

5. Common Pitfalls

Several recurring mistakes prevent effective resolution of the clw-network-exhausted error. Avoiding these pitfalls saves significant debugging time.

Misdiagnosing Resource Depletion Type: The error message does not specify which network resource is exhausted. Attempting to increase ephemeral ports when the actual problem is file descriptor exhaustion wastes effort. Always run diagnostic commands from Step 1 before applying fixes.

Applying Changes Without Persistence: Running sysctl -w commands without adding entries to /etc/sysctl.conf means changes survive only until the next reboot. Production systems require persistent configuration to survive restarts.

Neglecting Application-Level Connection Management: Kernel tuning addresses the ceiling, but well-behaved applications should manage connections efficiently. Always configure connection pooling, appropriate timeouts, and keepalive settings in application code alongside kernel adjustments.

Restarting Services Prematurely: Some changes require full daemon restart while others take effect immediately. Adding entries to limits.conf requires logout and re-login for user-level changes to apply. OpenClaw daemon configuration changes require systemctl restart, but kernel parameters via sysctl apply instantly.

Insufficient Monitoring After Fix: The network resource exhaustion often indicates legitimate growth in workload demands. Without monitoring systems tracking connection counts, file descriptor usage, and ephemeral port availability over time, teams discover exhaustion again when traffic increases.

The clw-network-exhausted error frequently appears alongside related networking failures in OpenClaw environments.

clw-port-conflict (Port Binding Failures): When ephemeral ports are exhausted, containers may fail to bind to configured service ports if the port allocation algorithm cannot find available ports in the expected range. This manifests as services refusing to start with “address already in use” messages even when no processes occupy those ports. The relationship is causal: both errors stem from network resource depletion but manifest at different layers.

clw-connection-timeout (Connection Establishment Failures): Connection tracking table exhaustion produces symptoms resembling network connectivity problems. Services appear unreachable, API calls time out, and health checks failβ€”regardless of whether physical network connectivity exists. The distinction lies in kernel logs showing dropped connection tracking entries versus genuine network path failures.

clw-resource-limit (General Resource Exhaustion): This umbrella error covers exhaustion of any allocated resource including memory, CPU, disk I/O, and network bandwidth. The clw-network-exhausted error is a specific instantiation where network resources trigger the more general clw-resource-limit condition. Resolving network-specific issues may require addressing other resource constraints if they contribute to cascading failures.

openclaw networking container exhaustion port connection