bc is a nice calculator that one can use under linux terminal.
a good exercise: count from 0 to 255 and convert it to binary
# install # debian/ubuntu apt install bc # fedora/redhat/centos yum install bc # run bc # let's count from 1 to 255 and use bc to convert it to binary bc 1.06.95 Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006 Free Software Foundation, Inc. This is free software with ABSOLUTELY NO WARRANTY. For details type `warranty'. scale=5 # calculate the maximum decimal possible value with 8 binary bits (two to the power of 8 = 8 binary digits) 2^8 256 obase=2; 0 0 # value of digit 1 is 1 obase=2; 1 1 # value of digit 2 is 2 obase=2; 2 10 obase=2; 3 11 value of digit 3 is 4 obase=2; 4 100 obase=2; 5 101 obase=2; 6 110 obase=2; 7 111 # value of digit 4 is 8 obase=2; 8 1000 obase=2; 9 1001 obase=2; 10 1010 obase=2; 11 1011 obase=2; 12 1100 obase=2; 13 1101 obase=2; 14 1110 obase=2; 15 1111 # value of digit 5 is 16 obase=2; 16 10000 obase=2; 17 10001 obase=2; 18 10010 obase=2; 19 10011 obase=2; 20 10100 obase=2; 21 10101 obase=2; 22 10110 obase=2; 23 10111 obase=2; 24 11000 obase=2; 25 11001 obase=2; 26 11010 obase=2; 27 11011 obase=2; 28 11100 obase=2; 29 11101 obase=2; 30 11110 obase=2; 31 11111 # value of digit 6 is 32 obase=2; 32 100000 obase=2; 33 100001 obase=2; 34 100010 obase=2; 35 100011 obase=2; 36 100100 obase=2; 37 100101 obase=2; 38 100110 obase=2; 39 100111 obase=2; 40 101000 obase=2; 41 101001 obase=2; 42 101010 obase=2; 43 101011 obase=2; 44 101100 obase=2; 45 101101 obase=2; 46 101110 obase=2; 47 101111 obase=2; 48 110000 obase=2; 49 110001 obase=2; 50 110010 obase=2; 51 110011 obase=2; 52 110100 obase=2; 53 110101 obase=2; 54 110110 obase=2; 55 110111 obase=2; 56 111000 obase=2; 57 111001 obase=2; 58 111010 obase=2; 59 111011 obase=2; 60 111100 obase=2; 61 111101 obase=2; 62 111110 obase=2; 63 111111 # value of digit 7 is 64 obase=2; 64 1000000 obase=2; 65 1000001 obase=2; 66 1000010 obase=2; 67 1000011 obase=2; 68 1000100 obase=2; 69 1000101 obase=2; 70 1000110 obase=2; 71 1000111 obase=2; 72 1001000 obase=2; 73 1001001 obase=2; 74 1001010 obase=2; 75 1001011 obase=2; 76 1001100 obase=2; 77 1001101 obase=2; 78 1001110 obase=2; 79 1001111 obase=2; 80 1010000 obase=2; 81 1010001 obase=2; 82 1010010 obase=2; 83 1010011 obase=2; 84 1010100 obase=2; 85 1010101 obase=2; 86 1010110 obase=2; 87 1010111 obase=2; 88 1011000 obase=2; 89 1011001 obase=2; 90 1011010 obase=2; 91 1011011 obase=2; 92 1011100 obase=2; 93 1011101 obase=2; 94 1011110 obase=2; 95 1011111 obase=2; 96 1100000 obase=2; 97 1100001 obase=2; 98 1100010 obase=2; 99 1100011 obase=2; 100 1100100 obase=2; 101 1100101 obase=2; 102 1100110 obase=2; 103 1100111 obase=2; 104 1101000 obase=2; 105 1101001 obase=2; 106 1101010 obase=2; 107 1101011 obase=2; 108 1101100 obase=2; 109 1101101 obase=2; 110 1101110 obase=2; 111 1101111 obase=2; 112 1110000 obase=2; 113 1110001 obase=2; 114 1110010 obase=2; 115 1110011 obase=2; 116 1110100 obase=2; 117 1110101 obase=2; 118 1110110 obase=2; 119 1110111 obase=2; 120 1111000 obase=2; 121 1111001 obase=2; 122 1111010 obase=2; 123 1111011 obase=2; 124 1111100 obase=2; 125 1111101 obase=2; 126 1111110 obase=2; 127 1111111 # value of digit 8 is 128 obase=2; 128 10000000 obase=2; 129 10000001 obase=2; 130 10000010 obase=2; 131 10000011 obase=2; 132 10000100 obase=2; 133 10000101 obase=2; 134 10000110 obase=2; 135 10000111 obase=2; 136 10001000 obase=2; 137 10001001 obase=2; 138 10001010 obase=2; 139 10001011 obase=2; 140 10001100 obase=2; 141 10001101 obase=2; 142 10001110 obase=2; 143 10001111 obase=2; 144 10010000 obase=2; 145 10010001 obase=2; 146 10010010 obase=2; 147 10010011 obase=2; 148 10010100 obase=2; 149 10010101 obase=2; 150 10010110 obase=2; 151 10010111 obase=2; 152 10011000 obase=2; 153 10011001 obase=2; 154 10011010 obase=2; 155 10011011 obase=2; 156 10011100 obase=2; 157 10011101 obase=2; 158 10011110 obase=2; 159 10011111 obase=2; 160 10100000 obase=2; 161 10100001 obase=2; 162 10100010 obase=2; 163 10100011 obase=2; 164 10100100 obase=2; 165 10100101 obase=2; 166 10100110 obase=2; 167 10100111 obase=2; 168 10101000 obase=2; 169 10101001 obase=2; 170 10101010 obase=2; 171 10101011 obase=2; 172 10101100 obase=2; 173 10101101 obase=2; 174 10101110 obase=2; 175 10101111 obase=2; 176 10110000 obase=2; 177 10110001 obase=2; 178 10110010 obase=2; 179 10110011 obase=2; 180 10110100 obase=2; 181 10110101 obase=2; 182 10110110 obase=2; 183 10110111 obase=2; 184 10111000 obase=2; 185 10111001 obase=2; 186 10111010 obase=2; 187 10111011 obase=2; 188 10111100 obase=2; 189 10111101 obase=2; 190 10111110 obase=2; 191 10111111 obase=2; 191 10111111 obase=2; 192 11000000 obase=2; 193 11000001 obase=2; 194 11000010 obase=2; 195 11000011 obase=2; 196 11000100 obase=2; 197 11000101 obase=2; 198 11000110 obase=2; 199 11000111 obase=2; 200 11001000 obase=2; 201 11001001 obase=2; 202 11001010 obase=2; 203 11001011 obase=2; 204 11001100 obase=2; 205 11001101 obase=2; 206 11001110 obase=2; 207 11001111 obase=2; 208 11010000 obase=2; 209 11010001 obase=2; 210 11010010 obase=2; 211 11010011 obase=2; 212 11010100 obase=2; 213 11010101 obase=2; 214 11010110 obase=2; 215 11010111 obase=2; 216 11011000 obase=2; 217 11011001 obase=2; 218 11011010 obase=2; 219 11011011 obase=2; 220 11011100 obase=2; 221 11011101 obase=2; 222 11011110 obase=2; 223 11011111 obase=2; 224 11100000 obase=2; 225 11100001 obase=2; 226 11100010 obase=2; 227 11100011 obase=2; 228 11100100 obase=2; 229 11100101 obase=2; 230 11100110 obase=2; 231 11100111 obase=2; 232 11101000 obase=2; 233 11101001 obase=2; 234 11101010 obase=2; 235 11101011 obase=2; 236 11101100 obase=2; 237 11101101 obase=2; 238 11101110 obase=2; 239 11101111 obase=2; 240 11110000 obase=2; 241 11110001 obase=2; 242 11110010 obase=2; 243 11110011 obase=2; 244 11110100 obase=2; 245 11110101 obase=2; 246 11110110 obase=2; 247 11110111 obase=2; 248 11111000 obase=2; 249 11111001 obase=2; 250 11111010 obase=2; 251 11111011 obase=2; 252 11111100 obase=2; 253 11111101 obase=2; 254 11111110 # this is the maximum decimal value of a 8 bit (1Byte) integer # why 255 and not 256? # because 256 is the value of the 9th digit obase=2; 255 11111111 # maximum value of all 8 binary (1x Byte) digits: 128+64+32+16+8+4+2+1 = 255
networking hardware and cables:
150m of LWL-patch cable LC UPC to LC UPC Duplex plug OM2 Multimode PVC (OFNR) 2.0mm fibre optic data cable https://www.fs.com/de/products/74394.html
interconnecting two 48x ports 1Gbit switches cisco 200-50GS switch with fibre gbic Transceiver Modul mit DOM – Cisco GLC-SX-MM Kompatibles 1000BASE-SX SFP 850nm 550m – https://www.fs.com/de/products/11774.html
ip net calculator:
now how do routers and computers calculate routes and subnets?
one can download the perl source here
for ipv6
network classes:
https://en.wikipedia.org/wiki/Classful_network
network planning tools:
https://www.netacad.com/courses/packet-tracer
https://www.solarwinds.com/free-tools/gns3-network-emulator
direct download link: https://www.solarwinds.com/downloads/GNS3FTEval.zip
Network monitoring software
https://www.solarwinds.com/network-performance-monitor/registration
designed to reduce network outages and improve performance
- Multi-vendor network monitoring
- Advanced alerting
- Critical path visualization with NetPath
Starts at 2.440 €
computer network schematics:
seems there are no standardized symbols… this is one possible (cisco) representation: (one can download high res network symbols from cisco)
cisco symbol for:
- file-server
- web server:
- micro web server:
- gigabit switch router
- androgynous person
drawing tools:
http://dia-installer.de/index.html
certificates and exercises:
https://www.netacad.com/courses/packet-tracer/introduction-packet-tracer
https://www.quora.com/What-are-some-of-the-best-resources-to-learn-Cisco-Packet-Tracer
Links:
http://www.ciscopress.com/articles/article.asp?p=2180208&seqNum=9
security:
after all switches and routers are computers: https://www.bleepingcomputer.com/news/security/cisco-warns-of-public-exploit-code-for-critical-switch-flaws/
rfcs:
https://tools.ietf.org/html/rfc791
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