2022-01-16 18:20:39 +00:00
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---
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title: "protocols"
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tags: [ "Documentation", "networking" ]
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---
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2020-01-02 00:04:35 +00:00
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# Protocols
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| TCP | UDP | ICMP |
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|:-----------------|:-----------------|:------------------|
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|Transmission Control Protocol | User Datagram Protocol | Internet Control Message Protocol |
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| Reliable and slow. | Fast but unreliable, such as VOIP. Provides checksums. | Dirty checks such as pings. |
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# Networking Addressing
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## IPv4
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Three address ranges pertain only to private networks, so no computer looks beyond the local router to resolve them:
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10.0.0.0 to 10.255.255.255
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172.16.0.0 to 172.31.255.255
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192.168.0.0 to 192.168.255.255
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In theory, networks should fall within one of 3 ranges, depending upon their first octet:
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Class A 1-127
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Class B 128 to 191
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Class C 192 to 223
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# Service Ports
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There are three types of port ranges:
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1 to 1023: Well-known and established ports.
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1024 to 49151 ICANN registered ports, used by various products, with limited oversight.
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49152 to 65535 Dynamic ports for ad hoc use.
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View a more complete list of ports with:
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> less /etc/services
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# ip
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Show all addresses with:
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> ip a{dd{ress}} s{how}
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If a link's not present, load it with:
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sudo ip link set dev wlp3s0 up
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Add an interface to a device as so:
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> sudo ip a add 192.168.0.15/255.255.255.0 dev eth1
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See network interfaces available on Fedora with:
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> less /etc/sysconfig/network-scripts/ifcfg-enp2s0f0
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or on Debian with:
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> less /etc/network/interfaces
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Mostly, interfaces will receive automatic addresses from a DHCP server. If this hasn't happened for you, you can request a dhcp address with:
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> sudo dhclient eth1
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View your current route to the internet with:
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> route
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... although on void this is:
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> routel
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If you don't have a route to the internet, you can manually specify the default gateway with:
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> sudo route add default gw 192.168.0.1
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... or ...
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> sudo ip route add default via 192.168.0.1
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