tcpip20250331.txt

(C) David Vajda
2025-03-31
TCP/IP auswendig

ASCII Code

NUL     Nullzeichen
SOH     Start of Heading
STX     Start of Text
ETX     End of Text
EOT     End of Transmission
ETB     End of Transmission Block
LF      Line Feed
FF      Form Feed
HT      Horizontal Tab
VT      Vertical Tab
CR      Carriage Return
DEL     Delete
BEL     Bell - Klingel
CAN     Cancel
ESC     Escape?
SI      Shift Ins
SO      Shift Out
DC1     Device Control 1
... DC4

RS232 - CCITT-1

GND - Ground
TxD - Transmit Data
RxD - Recieve Data
CTS - Clear 2 send
RTS - Ready 2 send
DSR - Data Set Ready
DTR - Data Terminal Ready

Terminal - Datenendgeraet
Modem - Datenuebertragungsgeraet

1 Start Bit
1 oder 2 Stop Bit
keine gerade ungerade Paritaet
5 6 7 8 oder 9 Data Bits

Baudrate
    1200
    2400
    4800
    9600
    ...

Baud: 1 Zeichen pro Sekunde des Entsprechenden Zeichensatzes

UBRR - USART Baud Rate Register
UBRRL UBRRH
UCSRC UCSRB UCSRA - USART Controll and Status Register
UDR - USART Data Register

TXEN - Transmit Enable
RXEN - Recieve Enable

UDRE - USART Data Register Empty
URSEL - ...
UCSZ1 UCSZ0

Data Flow Controll
    Hardware
    Software
    Protokoll

Application Layer Ports
    15  netstat
    20  ftp
    22  ssh
    25  smtp
    53  dns
    80  http
    110 pop3
    143 imap
    443 https
    587 smtps/imaps?

DNS
    A       IPv4 - name
    AAAA    IPv6 - name
    PTR     Pointer Record
    TXT     Text Record
    CNAME   Cannonical Name Record - kanonisch - Richtschnur
    MX      mail eXchange Record

TCP
    Source Port (2 Byte)
    Destination Port (2 Byte)
    Sequence Number (4 Byte)
    Acknowlegement Number (4 Byte)
    Data Offset (5 Bit)
    Reserved
    Flags
        ...
    Recieve Window
    Checksum
    Urgent Pointer
    Options?

IP
    Source Address
    Destination Address
    TTL - Time 2 Live
    DSCP -
    IHL
    ...

Binarys - TCP/IP
    iptables ifconfig ip
    route traceroute tracepath
    telnet
    netstat
    ping
    wget
    nslookup
    whois
    ...

iptables
    chains
    tables

    tables
        filter
        nat
        mangle
        raw

    chains
        INPUT
        PREROUTING
        FORWARD
        POSTROUTING
        OUTPUT

    ACTIONS
        DROP
        ACCEPT
        REJECT
        LOG
        ...

    -d DESTINATION ADDRESS
    -s SOURCE ADDRESS

    -dport DESTINATION PORT
    -sport SOURCE PORT

    -p PROTOCOLL
        icmp/tcp/udp

    -j ACTION


GPG - Encryption Algorithms
    IDEA 3DES CAST5 BLOWFISH
    AES AES-192 AES-256
    TWOFISH
    CAMELLIA-192 CAMELLIA-256 CAMELLIA-512