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Shuobude Technical Blog

website·Indexed 29 days ago

https://www.shuobude.top

A collection of technical guides and notes covering Linux administration (RHEL, Debian), Kubernetes (K8S) RBAC and ABAC, Docker, Nginx, and network configuration. Includes practical tutorials on vsftpd, systemd, GitLab optimization, and various shell scripting and Python automation tasks.

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What's inside Shuobude

  1. Overview of Network Teaming Runners

    Network teaming logically links NICs for failover or higher throughput. RHEL 7 uses a kernel driver and the teamd user-space daemon to implement this. The behavior of the team is determined by the 'runner' selected:

    • broadcast: Transmits every packet from all ports.
    • roundrobin: Transmits packets in a round-robin fashion across ports.
    • activebackup: A failover runner that monitors link changes and selects an active port for data input.
    • loadbalance: Monitors traffic and uses a hash function to balance packets across ports.
    • lacp: Implements the 802.3ad Link Aggregation Control Protocol (LACP), using the same port selection as loadbalance.

  2. Overview of firewalld and Zone Logic

    firewalld is the default host-level firewall management tool for RHEL. It manages the Linux kernel netfilter subsystem via low-level tools like iptables, ip6tables, and ebtables.

    Incoming traffic is routed to zones based on the first matching rule in this order:

    1. Source address match (source rule).
    2. Incoming interface match (filter setting).
    3. Default zone (a pointer to another defined zone).

    By default, new network interfaces are assigned to the public zone unless overridden by NetworkManager.

  3. Overview of sniproxy and dnsmasq for streaming access

    This solution uses a combination of dnsmasq and sniproxy to enable access to streaming services like Netflix and Disney+ without requiring a traditional VPN or proxy client (ladder). Note that because sniproxy relies on proxy servers, network speeds and stability may vary.

  4. Overview of firewalld in RHEL

    firewalld is the default host-level firewall management tool in RHEL 7. It manages the Linux kernel netfilter subsystem via low-level tools like iptables, ip6tables, and ebtables. To prevent conflicts and accidental erasure of firewall configurations, it is recommended to mask the legacy .service files for iptables, ip6tables, and ebtables using systemctl.
    for SERVICE in iptables ip6tables ebtables; do
  systemctl unmask ${SERVICE}.service
done

  5. Overview of theme layout components

    The theme layout consists of global navigation elements, page-specific content areas, and interface utility buttons. All of these components can be customized via the global theme options or within a specific page's frontmatter.

    Global Layout Components:

    • Navbar
    • Sidebar
    • Footer

    Page-Specific Elements:

    • Breadcrumbs (Path navigation)
    • Page title and page information
    • Table of Contents (TOC)
    • Page meta information (Contributors, update time, etc.)
    • Comments section

    Interface Utility Elements:

    • Dark mode toggle button
    • Back-to-top button
    • Print button

  6. Overview of Network Teaming Runners

    Network Teaming allows multiple NICs to be linked logically for failover or increased throughput. The behavior of the team is determined by the 'runner' selected:

    • broadcast: Transmits every packet from all ports.
    • roundrobin: Transmits packets in a round-robin fashion across ports.
    • activebackup: Failover runner that monitors link changes and selects an active port for data input.
    • loadbalance: Monitors traffic and uses a hash function to balance packets across ports.
    • lacp: Implements the 802.3ad Link Aggregation Control Protocol (LACP), using the same port selection as loadbalance.

  7. Overview of the sed stream editor

    sed (stream editor) is a non-interactive text editor used to process standard input from sources such as keyboard input, text redirection, strings, variables, or pipes. It operates on a line-by-line basis, storing the current line in a temporary buffer called the "pattern space." After processing the buffer, sed outputs the content to the screen or writes it to a file. Note that by default, sed prints the result to the screen and does not modify the original file unless output is redirected or a specific write-back flag is used.

  8. Overview of GRE over IPsec vs IPsec over GRE

    GRE (Generic Routing Encapsulation) provides a point-to-point tunnel that supports non-IP traffic and multicast but lacks encryption. IPsec provides encryption but does not support routing or multicast.

    GRE over IPsec (Recommended): GRE encapsulates the private IP, and IPsec encrypts the resulting GRE packet. This supports multicast and is the standard for site-to-site interconnects. In this mode, the IPsec ACL matches the tunnel flow (source/destination of the tunnel endpoints), and the policy is applied to the physical interface.

    IPsec over GRE: Data is encrypted first, then encapsulated in GRE. This is rarely used as it does not support multicast. The IPsec ACL matches the business traffic flow, and the policy is applied to the tunnel interface.

  9. Overview of iSCSI Remote Block Storage

    iSCSI (Internet Small Computer System Interface) is a TCP/IP-based protocol used to emulate high-performance local SCSI storage buses over IP networks. It allows for the creation of Storage Area Networks (SAN) across LANs, WANs, and the Internet, enabling location-independent data storage and retrieval. iSCSI preserves the SCSI Command Descriptor Block (CDB) command set but encapsulates it within standard TCP/IP packets. It can be implemented via software (OS TCP/IP stack), TCP Offload Engines (TOE) on specialized NICs, or hardware Host Bus Adapters (HBA) for higher performance.

  10. Overview of Linux Access Control Lists (ACLs)

    Standard Linux file permissions are limited to the owner, a single group, and others. ACLs allow for more refined permissions by granting access to specific users (via username or UID) and specific groups (via group name or GID) using the standard rwx (read, write, execute) flags. ACLs can be set on individual files or directories; new files and subdirectories can inherit ACL settings from a parent directory's default ACL.

  11. Overview of Let’s Encrypt Certificate Authority

    Let’s Encrypt is a free, open, and automated Certificate Authority (CA) operated by the Internet Security Research Group (ISRG). It provides digital certificates required to enable HTTPS (SSL/TLS) for websites to create a more secure and privacy-respecting web environment.

    Key principles of Let’s Encrypt include:

    • Free: Anyone with a domain name can obtain trusted certificates at no cost.
    • Automated: Software running on servers can interact directly with Let’s Encrypt to obtain, configure, and automatically renew certificates.
    • Secure: It promotes TLS security best practices for both the CA and website operators.
    • Transparent: All issued or revoked certificates are publicly logged.
    • Open: The protocols for automatic issuance and renewal are published as open standards.
    • Collaborative: It is a community effort designed for the benefit of the entire internet, not controlled by a single organization.

  12. Generate pages using Markdown in VuePress

    VuePress generates pages primarily from Markdown files, making it suitable for creating documentation or blog sites. To create different pages, you should organize and write Markdown files according to the desired file structure, which VuePress then converts into corresponding pages.