CentOS 7 Network Configuration and Troubleshooting Notes

Viewing TCP/IP Parameters in CentOS 7

• To check TCP/IP settings, use either the CentOS GUI or terminal commands.

• Accessing Settings via GUI:

  • Go to Applications > System Tools > Settings > Network.

  • Highlight the active network connection to view Ethernet Device settings. This interface provides a user-friendly way to manage network configurations.

  • When set to DHCP, the IP address is assigned automatically from an external server, simplifying the process of connecting to different networks without manual input.

• Using Terminal Commands to View Settings:

  • The ifconfig command displays network adapter information, including IP address, netmask, and broadcast address.

  • Note: ifconfig has been deprecated in some systems, which may limit its use in future versions of Linux.

  • The ip command is preferred, offering more features and flexibility, requiring multiple sub-commands:

  • Use ip -d addr for detailed IP addresses associated with each interface, showing additional information such as state and associated protocols.

  • Use ip -d route for the default gateway, revealing the routing table information crucial for determining packet paths.

  • DNS lookup settings can be found in the file /etc/resolv.conf. This file is key for resolving domain names into IP addresses during web requests.

  • Example: DNS server notation is nameserver 8.8.8.8 (Google DNS), ensuring high availability and reliability when querying domain names.

Checking Network Resources in CentOS 7

• Ping Command:

  • Use ping to test communication between computers, useful for troubleshooting network connectivity.

  • A successful ping returns how many bytes were sent and the response time, which can help assess network speed.

  • If the command fails, it indicates a problem (e.g. "Destination Host Unreachable"), prompting further investigation into network settings.

  • Example: ping 192.168.1.1 or ping www.sun.com (using domain name) showcases the command’s versatility in testing both local and external connectivity.

• Traceroute Command:

  • Use traceroute to see every hop in a network connection, thus providing insights into the path packets take to reach their destination.

  • Displays paths through switches, routers, and firewalls, enabling identification of network bottlenecks or failures.

  • May display *** symbols when communication fails or is blocked, indicating points of failure.

Accessing Network Resources in CentOS 7

• Accessing shared files in CentOS is similar to Windows 10, making it easy for users familiar with both systems to navigate.

• Mounting a Share:

  • Create a directory for the mount point, which serves as the local access point for the remote share.

  • Use the mount command with the share's UNC path and the destination directory, establishing the connection to the shared resource itself.

  • Example Command: mount -t cifs //server/share /mnt/point -o username=user,password=pass illustrates how to specify authentication details and network locations.

  • After the share is mounted, change to the mount directory and view files using command ls, allowing seamless access to shared resources.

  • Alternatively, use File Browser to view mounted file entries visually, which provides an accessible interface for file management.

  • Be aware that if the computer sharing files shuts down, the directory may appear empty until it's remounted, which is critical to note for continuous access to shared data.