When working with VPN clients like vpnc and manually modifying routing tables, it's common to encounter situations where network connectivity breaks completely. The classic symptoms include:

ping: sendto: Network is unreachable
traceroute: bind: Can't assign requested address

While rebooting always works to restore default routes, developers need a more surgical approach. Here's how to completely reset your routing table without restarting:

# Step 1: Flush all existing routes
sudo route -n flush

# Step 2: Restore default routes
sudo ifconfig en0 down && sudo ifconfig en0 up

Replace en0 with your active network interface (check with ifconfig or networksetup -listallhardwareports).

For more complex scenarios where basic interface reset doesn't work, try this comprehensive approach:

# Disable Wi-Fi (or Ethernet)
sudo networksetup -setairportpower en0 off

# Flush DNS cache
sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder

# Clear all routes
sudo route -n flush
sudo route -n flush all

# Re-enable interface
sudo networksetup -setairportpower en0 on

For frequent VPN users, create a recovery script (netfix.sh):

#!/bin/bash

INTERFACE="en0"

echo "[+] Flushing routing tables..."
sudo route -n flush
sudo route -n flush all

echo "[+] Resetting interface $INTERFACE..."
sudo ifconfig $INTERFACE down
sleep 2
sudo ifconfig $INTERFACE up

echo "[+] Restoring default route..."
sleep 5  # Wait for DHCP
route -n get default

echo "[+] Network reset complete"

If problems persist after reset:

• Check for leftover VPN processes: ps aux | grep vpn
• Verify DNS with: scutil --dns
• Inspect system logs: log show --predicate 'process == "configd"' --last 10m

Remember that MacOS (especially newer versions) handles routing differently:

• Service order matters (System Preferences > Network)
• IPv6 can interfere - try disabling temporarily
• VPN clients often create high-priority routes

When working with vpnc or other VPN clients on macOS, we often need to manipulate routing tables for local network access. But things can go wrong quickly:

$ ping google.com
ping: sendto: Network is unreachable

$ traceroute example.com
traceroute: bind: Can't assign requested address

After a fresh boot, macOS creates these essential routes automatically:

• Default gateway route
• Local network routes
• Loopback interface route
• Multicast/broadcast routes

Here's how to restore routing tables without rebooting:

# Step 1: Flush all existing routes
sudo route -n flush

# Step 2: Bring interfaces down and up (en0 for wired, en1 for wireless)
sudo ifconfig en0 down
sudo ifconfig en0 up

# Alternative: Use networksetup for Wi-Fi
sudo networksetup -setnetworkserviceenabled Wi-Fi off
sudo networksetup -setnetworkserviceenabled Wi-Fi on

For frequent VPN users, create a reset script:

#!/bin/bash

# Reset routing
echo "Flushing routes..."
sudo route -n flush

# Reset primary interface
INTERFACE=$(route -n get default | grep 'interface' | awk '{print $2}')
echo "Resetting interface $INTERFACE..."
sudo ifconfig $INTERFACE down
sudo ifconfig $INTERFACE up

# Verify restoration
echo "New routing table:"
netstat -rn

For complete network stack reset:

# Release and renew DHCP
sudo ipconfig set en0 DHCP
sudo ipconfig set en0 NONE  # For some configurations
sudo ipconfig set en0 DHCP

Check these when routes misbehave:

# Show current routing table
netstat -rn

# Verify interface status
ifconfig

# Check DNS resolution
dscacheutil -q host -a name google.com