Linux Network Management-Basics

MAC: Media Access Control

CSMA/CD: Carrier Sense Multi access/collision Detection, carrier-listening multi-access conflict detection

Hub: hub

Repeater:

Network Bridge:

Switch:

Mac table:

Conflict domain:

Router:

Routing table:

Routing Table Convergence:

Routing protocol:

Default route:

Route Merge:

Subnets:

Hyper-Net:

Gateway:

Subnet Mask:

ARP: Address Resolution Protocol, addresses resolution Protocol, IP->MAC

RARP: Revise address Resolution Protocol, reverse URL Resolution Protocol, MAC->IP

Port:

Socket: IP and Port bindings.

MTU: Max Transfer Unit, Maximum transmission unit.

ICANN: Internet Name and digital address distribution agency.

Osi:

• Physical layer: Message preamble.
• Data link layer: MAC.
• Network layer: IP.
• Transport layer: TCP, UDP.
• Session Layer:
• Presentation layer: Compress, encrypt.
• Application layer: HTTP.

Tcp / ip:

• Physical Layer:
• Data Link Layer:
• Network layer:
• Transport Layer:
• Application layer:

IP message:

• IP VERSION:IP version, 4b.
• HDR Les: Packet head length, 4b.
• Type of Service (TOS): type of services, whether expedited, 8b.
• Total length: Message overall, 16b.

• Identification (Fragment ID): Slice id,16b.
• R:
• Df:don ' t Fragment, no sectioning mark, 1b.
• Mf:more Fragment, slice identification, 1b.
• Fragment offset: Slice offset, 13b.

• Time-to-live (TTL): Time to live, 8b.
• Protocol: Upper layer Protocol (TCP, UDP), 8b.
• Header Checksum: Header checksum, 16b.

• Source IP Address: 32b.

• Destination IP Address: Destination IP addresses, 32b.

• Options: Option up to 40b.

• Data:.

IP Address:

The host bits are all 0 for the network address, and the host bit is 1 for the broadcast address.

• Class A: Starting with 0, 1-126, (2^7-1), 255.0.0.0
• Class B: Starting with 10, 128-191, (2^14), 255.255.0.0
• Class C: Starting with 110, 193-223, (2^21), 255.255.255.0
• Class D: Starting with 1110, 224-239
• Class E:

Private Address:

Class A: 10.0.0.0/8

Class B: 172.16.0.0-172.31.0.0/16

Class C: 192.168.0.0-192.168.255.0/24

TCP: Transmission Control Protocol, transmission protocol.

UDP: User Datagram Protocol, Subscriber Datagram Protocol.

TCP message:

• Source port number: 16b.
• Destination Port number: Destination port, 16b.

• Sequence number: Serial, 32b.

• Acknowledgement number: Confirm, 32b.

• Header Length: First ministerial degree, 4b.
• Reserved: Reserved bit, 6b.
• URG: Emergency bit, 1b.
• ACK: Confirm bit, 1b.
• PSH: Push bit, not stay in buffer, 1b.
• RST: Reset bit, connection reset, 1b.
• Syn:1b.
• Fin:1b.
• Window Size: 16b.

• TCP Checksum: Checksum, 16b.
• Urgent Pointer: Emergency pointer, 16b.
• Options: Optional.
• Data:.

Three-time handshake:

• syn=1,sn=100-syn_sent
• syn=1,ack=1,sn=100,an=101-syn_recv
• Ack=1,sn=101,an=101-established

Four-time disconnection:

• Fin=1,ack=1,sn=x,an=z
• Ack=1,sn=z,an=x+1
• Fin=1,ack=1,sn=y,an=x
• Ack=1,sn=x

DHCP: Dynamic Host configuration Protocol. config protocol

Lo: local loopback

Ethernet network card:EthX

Point-to-point connection:pppx

Rhel5:/etc/modprobe.conf

Alias

Rhel6:/etc/udev/rules.d/70-persistent-net.rules

Ifconfig

• Role

View network card information.

Ifconfig EthX Ip/mask [Up|down], the configured address takes effect immediately, but restarting the network service or host fails.

Network services:

rhel5:/etc/init.d/network {Start|stop|status|restart}

Rhel6:/etc/init.d/networkmanager {Start|stop|status|restart}

• Options

-A: Displays all interface configuration information.

Route

• Role

Manage routing. The changes made fail after restarting the network service or host.

Add: Adding

-host: Host Routing

-net: Network Routing

Route add-net|-host DEST GW Nexthop

Route add default GW nexthop

Del: Delete

-host:

-net:

Route Del-net Nexthop

• Options

-n:numeric, displays information about each organization or port in a digital manner.

Network configuration file:

/etc/sysconfig/network

Network Interface configuration file:

/etc/sysconfig/network-scripts/ifcfg-interface_name

Device=: The associated device, to be consistent with the second half of the file name.

BOOTPROTO={STATIC|NONE|DHCP|BOOTP}: The bootstrap protocol, to use static addresses, use the statics or NONE;DHCP to represent the use of the DHCP server to obtain addresses.

Ipaddr=:ip address.

netmask=: Subnet mask.

Gateway=: Sets the default gateway.

Onboot=: Whether this network interface is activated automatically when powered on.

Hwaddr=: Hardware address, to be consistent with the address in the hardware, can be saved.

Userctl={yes|no}: Indicates whether an ordinary user is allowed to control this interface.

PEERDNS={YES|NO}: The DNS address specified by the DHCP server is accepted when Bootproto is DHCP.

Restart Network Service:

/etc/init.d/network restart

Routing:

/etc/sysconfig/network-scripts/route-ethx

Add format one:

DEST via Nexthop

Add format two:

address0=

netmask0=

gateway0=

DNS server Specifies the method:

/etc/resolv.conf

NameServer dns_ip_1

NameServer dns_ip_2

NameServer Dns_ip_3

Specify local resolution:

/etc/hosts

Destination host IP host name host Alias

Dns-->/etc/hosts-->dns Cache-->dns Server

Configure host Name:

/etc/sysconfig/network

Hostname=

Networking={yes|no}

Networking_ipv6={yes|no}

RHEL5:

　　Setup:system-config-network-tui

System-config-network-gui

Iproute2:

　　Ip:

Link: Configure network interface properties.

Show:ip-s Link Show

Set:ip Link set DEV {up|down}

Addr: Protocol address.

Add: Adds an address.

IP addr Add ADDRESS dev Dev

Del: delete address.

IP addr del ADDRESS dev Dev

Show: Displays address information.

IP addr Show Dev dev to PREFIX

Flush: Clears the address.

IP addr Flush Dev dev to PREFIX

Route: Routing.

A network card can use multiple addresses:

Network devices can use aliases.

Ethx:x

Configuration method:

Ifconfig ethx:x Ip/netmask

/etc/sysconfig/network-scripts/ifcfg-ethx:x

Device=ethx:x

Non-primary addresses cannot be dynamically obtained using DHCP.

Linux Network Management-Basics