TCP IP
| The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP). Early versions of this networking model were known as the Department of Defense (DoD) model because the research and development were funded by the United States Department of Defense through DARPA. | |
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| wikipedia:: Internet protocol suite |
Broadcast
- When a client tries to get an ip?
- 255.255.255.255?
- Address for sending something to everyone
- E.g. When a client is looking for who has a particular ip or mac address
- IP addresses
- One of the two principal namespaces of the Internet (the other is DNS).
- Private/Public Address
- Public IPs (routable)
- Private IPs (unroutable)
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- 192.168.
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- Internal/External Address
- Static/Dynamic Address
- Static can be set on the client in its adapter settings or by an external DHCP service by e.g. MAC address reservations/assignments
- IPv4
- 32 bits
- IPv6
- 128 bits
- Ports
- like channels or tunnels
- Only one port can be used per app, e.g. ssh, ftp, etc.
- 1 - to 65535
- Common Ports
- 80 http
- 443 https
- 20 ftp data
- 21 ftp
- 22 ssh
- 25 smtp
- 43 WHOIS
- 53 DNS
- 67 DHCP server
- 68 DHCP client
- 143 IMAP mail
- 631 CUPS
- 666 Doom game
- internal and external port forwards don’t need to be the same (when defining the port forwarding rule)
- don’t use the normal default ports externally, choose higher up ones, like 10000 or above or something
- A very minor security step, doesn't do much, but why not? It just makes it slightly less obvious and less likely to be found via scanning and scripts, etc. Makes scanning a little more costly.
- 54321
- 5432
- 5433
- Port Knocking
- DHCP
- TCP vs UDP
- TCP
- establish handshake and maintain link
- UDP
- just sends packets in whatever order without necessarily handshaking and verifying?
- more of a solid stream, what you get you get
- Better for streaming multimedia
- TCP
- Subnetwork
- A logitcal subdivision of an ip network - splitting a network in two or more networks
- Devices in a subnet have IPs that are split in 2 fields: the network number or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific host or network interface.
- network number aka routing prefix
- rest field aka host identifier
- identifies a specific device
- Traffic is exchanged between subnetworks through routers when the routing prefixes of the source address and the destination address differ. A router serves as a logical or physical boundary between the subnets.
- Examples
- 198.51.100.0/24
- 24 bits allocated for the network prefix
- remaining 8 bits reserved for host addressing
- Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network.
- /32 - single IP
- /24 - 256 IPs
- /16 - 65,536 IPs
- /8 - 16,777,216 IPs
- 198.51.100.0/24
- Calculator
- Subnet mask
- Address Classes
- A
- e.g. /8 with subnet mask 255.0.0.0
- B
- e.g. /16 with subnet mask 255.255.0.0
- C
- e.g. /24 with subnet mask 255.255.255.0
- A
3 Dumb routers
Test 2
Segmentation/isolation
- 3 dumb routers
TCP IP
Interactive graph
On this page
TCP IP
DNS
Network Socket
Broadcast
DMZ (networking)
ICMP
3 Dumb routers
Segmentation/isolation