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--- notes:computer_network [2026/02/08 03:46] – created - external edit 127.0.0.1
+++ notes:computer_network [2026/04/05 01:58] (current) – azman
@@ Line 1: / Line 1: @@
 ====== Computer Network ======
+Useful stuff?
 ===== IPV4 Addresses =====
@@ Line 25: / Line 27: @@
 https://test-ipv6.com/
 </file>
+====== Cisco Stuff ======
+My experience configuring cisco device(s). I'm just dumping my text notes for now... will try to make this prettier some other time 8-)
+Status: At the moment, my DHCP server on 1841 is running and correctly providing machines on my switch with proper IPs. NAT works.
+===== Cisco 1841 Router =====
+I want to setup a LAN in my lab so that I can have a central login server for all Windows machines. One interface on the 1841 will be for LAN, while the other will be connected to Uni's network.
+<file text cisco-1841_config.txt>
+------------
+general info
+------------
+- note that default hostname for device is 'Router'
+- basic prompt is {hostname}>
+- privileged prompt is {hostname}#
+- to reset configuration, reboot and send break within 60 seconds?
+  = on minicom, hit ctrl+a-f
+  = should get rommon console (i.e. rommon {1-based index}>)
+- configure router to bypass configuration
+  = type 'confreg 0x2142'
+  = type 'reset'
+- configure router to use configuration
+  = type 'confreg 0x2102'
+  = type 'reset'
+-----------------------------
+configuring cisco 1841 router
+-----------------------------
+- pc serial port connect to rj45 console port on 1841
+  = need usb2serial for most pc nowadays
+  = need an rj45-rs232 cable!
+- i use minicom on slackware
+  = use 9600 8n1 with no flow control
+- start router, skip all wizards/auto-config
+  = should get 'Router>' prompt
+  = type <command> ? for specific help
+  = typing help will tell you this :p
+- type 'enable' to get to global config privileged mode
+  = should get 'Router#' prompt
+* configure basics
+- type 'conf t' to start configuring
+  = shortcut for 'configure terminal'
+- configurations:
+  = no ip domain lookup
+    - this disables domain lookup (do not use dns)
+  = no logging console
+    - this disables log messages display on console
+  = hostname my1841
+    - changes router hostname (prompt should reflect)
+  = enable secret 0 my1pass
+    - default level is 5? but the command above still sets 5
+    - tested 20161208: show running-config | include enable
+    - maybe add keyword level before 0?
+  = service password-encryption
+    - enables password enryption (on clear text? not needed for secret?)
+- type 'exit' in config-mode then write
+* configure wan & lan ports
+- type 'conf t' to start
+- configurations:
+  = interface fas0/0
+    - prompt appended with (config-if)
+    - configuring fast ethernet port 0
+  = description WAN_LINK
+    - just a label
+  = ip address dhcp client-id FastEthernet0/0
+    - set to be dhcp client
+  = no shut
+  = exit
+    - get back to global config
+  = interface fas0/1
+    - configuring fast ethernet port 1
+  = description LAN_LINK
+  = ip address 192.168.100.1 255.255.255.0
+    - set private local ip
+  = no shut
+  = exit
+    - get back to global config
+- type 'exit' in config-mode then write
+* configure dhcp for lan
+- type 'conf t' to start
+- configurations:
+  = ip dhcp pool my1dhcp
+    - prompt appended with (dhcp-config)
+  = network 192.168.100.0 255.255.255.0
+  = default-router 192.168.100.1
+  = dns-server 8.8.8.8
+  = exit
+    - get back to global config
+  = ip dhcp excluded-address 192.168.100.1 192.168.100.9
+    - 'reserve' these for network management
+- type 'exit' in config-mode then write
+* configure gui http server
+- type 'conf t' to start
+- configurations:
+  = username admin privilege 15 password check
+  = ip http server
+  = ip http secure-server
+  = ip http authentication local
+- type 'exit' in config-mode then write
+* link wan & lan using nat (NOT TESTED!)
+- type 'conf t' to start
+- configurations:
+  = interface fas0/0
+  = ip nat outside
+  = exit
+  = interface fas0/1
+  = ip nat inside
+  = exit
+  = access-list 100 permit ip any any
+    - simple access-list - just allow everything
+  = ip nat inside source list 100 interface fas0/0
+    - anything sourced from ACL 100 is permitted
+    - outside interface (FastEthernet 0/0) is the port for PAT
+- type 'exit' in config-mode then write
+</file>
+===== Cisco 3560 Switch =====
+This switch actually have a [[https://en.wikipedia.org/wiki/Network_layer|layer 3]] implementation (well, provided you get the correct software image) that enables routing.
+I just need a simple switch configuration for now.
+<file text cisco_3560_config.txt>
+------------
+general info
+------------
+- note that default hostname for device is 'Switch'
+- basic prompt is {hostname}>
+- privileged prompt is {hostname}#
+* to reset
+- delete flash:vlan.dat
+- erase startup-config
+- reload
+  = do not save anything if prompted
+* to check flash content
+- dir flash:
+* show 'show' options
+- show ?
+* to check boot settings
+- show boot
+(configure boot system)
+- boot system flash: (???)
+-----------------------------
+configuring cisco 3560 switch
+-----------------------------
+* configure basics
+- to start configuring
+  # configure terminal
+- change hostname to 'my3560'
+  # hostname my3560
+- set password 'my1pass' to enable
+  # enable secret my1pass
+- exit config-mode
+  # exit
+- write/save config
+  # write
+</file>
+//**Note**: The  default 'factory' image should be ''c3560-ipbase-mz.122-53.SE/c3560-ipbase-mz.122-53.SE.bin'', but the one I got has ''c3560-advipservicesk9-mz.122-37.SE.bin''. I guess this is the image that provides layer 3 stuffs.//