Resolving Connectivity
Common Connectivity Issues and Solutions
Resolving network connectivity problems requires a structured approach and targeted interventions.
Connectivity Issue Categories
Issue Type |
Symptoms |
Potential Solutions |
IP Configuration |
No IP address |
DHCP reconfiguration |
DNS Resolution |
Cannot resolve hostnames |
DNS server modification |
Routing Problems |
Packets not forwarding |
Route table adjustment |
Firewall Blocking |
Connection refused |
Firewall rule modification |
Network Reconfiguration Workflow
graph TD
A[Identify Connectivity Issue] --> B{Issue Type}
B -->|IP Config| C[Reconfigure Network Interface]
B -->|DNS| D[Update DNS Settings]
B -->|Routing| E[Modify Routing Tables]
B -->|Firewall| F[Adjust Firewall Rules]
C --> G[Restart Network Service]
D --> G
E --> G
F --> G
G --> H[Verify Connectivity]
Network Interface Reconfiguration
## Bring down network interface
sudo ifdown eth0
## Bring up network interface
sudo ifup eth0
## Renew DHCP lease
sudo dhclient -r
sudo dhclient
DNS Configuration Fix
## Edit DNS configuration
sudo nano /etc/netplan/01-netcfg.yaml
## Example DNS configuration
network:
version: 2
renderer: networkd
ethernets:
eth0:
addresses: [192.168.1.100/24]
nameservers:
addresses: [8.8.8.8, 1.1.1.1]
routes:
- to: default
via: 192.168.1.1
## Apply network configuration
sudo netplan apply
Firewall Configuration
## Check firewall status
sudo ufw status
## Allow specific port
sudo ufw allow 22/tcp
## Enable firewall
sudo ufw enable
Routing Table Management
## View routing table
ip route show
## Add static route
sudo ip route add 192.168.2.0/24 via 192.168.1.1
## Delete route
sudo ip route del 192.168.2.0/24
LabEx Connectivity Best Practices
At LabEx, we emphasize:
- Systematic troubleshooting
- Minimal configuration changes
- Comprehensive testing after modifications
Final Connectivity Verification
- Ping local gateway
- Test external DNS resolution
- Verify internet connectivity
- Check application-specific connections