tcpip20250317.txt

(C) David Vajda
2025-03-17
TCP/IP Networking

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
HT          Horizontal Tab
VT          Vertical Tab
LF          Line Feed
FF          Form Feed
CR          Carriage Return
DEL         Delete
CAN         Cancel
BS          Backspace
ACK         Acknowledge/Acknowlege?
NAK         No Acknowlegemenet
SYN?
SI          Shift In
SO          Shift Out
DC1         Device Controll 1
DC2
DC3
DC4

RS-232
TxD     Transmit Data
RxD     Recieve Data
RTS     Ready To Send
CTS     Clear To Send
DSR     Data Set Ready
DTR     Data Terminal Ready

Sub-D-9
    Buchse
    stecker

Terminal: Datenendgeraet
Datenuebertragungsgeraet

1 Startbit
1 oder 2 Stopbit
no even odd parity bit
5 6 7 8 9 stop bit

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

UCSZ2? UCSZ1 UCSZ0
UBR???

TXEN
RXEN

UDRE

Baudrate
    UBRR <- CPU-Takt-Rate / (16 * Baudrate) - 1     ???

Baudot-Code: CCITT-1
CCITT-5

Asynchron

1 Bd = 1 Zeichen eines Zeichensatz pro Sekunde

Clear: Erlaubnis
Ready: Bereit
Request: Anfrage
Acknowlege: Bestaetigung

Handshaking - Data Flow Controll
    protokoll?
    hardware
    software

X-ON/X-OFF Protocoll - Strg-Q/Strg-S: Bash
ACK/NAK

Application Layer Ports
    15 NETSTAT
    20 FTP
    22 SSH
    25 SMTP
    53 DNS
    80 HTTP
    443 HTTPS
    110 POP3
    143 IMAP
    587 SMTPS

RECORDS DNS
    A IPv4 Name Address
    AAAA
    TXT
    MX Mail eXanchange Record
    PTR Pointer Record
    CNAME - Canonical Name Record - Canonical - kanonisch - richtschnur

TCP/IP Pakete
    TCP
        Source Port (2 Byte)
        Destination Port (2 Byte)
        Sequence Number (4 Byte)
        Acknowlegement Number (4 Byte)
        Data Offset (5 Bit?)
        Reseverd
        Flags
            ...
    IP
        ...
        Source IP Address
        Destination IP Address

    IP
        IHL DSCP TTL
        Source IP Address
        Destination IP Address

iptables
    tables
    chains

    tables
        ... nat mangle raw
    chains
        PREROUTING
        INPUT
        FORWARDING
        OUTPUT
        POSTROUTING

    action:
        DROP
        ACCEPT
        REJECT
        LOG

    -d DESTADDR
    -s SOURCEADDR
    --source-port SOURCEPORT
    --destination-port DSTPORT
    -j ACTION
    -A CHAIN
    -p PROTCOLL

ip ifconfig iptables
netstat route nslookup (reverse-dns-lookup?)
hostname host
whois
telnet
ping
dig
traceroute


Encryption Algorithms
    IDEA 3DES CAST5 BLOWFISH
    AES AES192 AES256
    TWOFISH
    CAMELLIA-192 CAMMELIA-256 CAMMELIA-512