= Linux Networking =

<<TableOfContents>>

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== Connections ==

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== Name Resolution ==

See [[Linux/DNS|here]].

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== Routing ==

By default, the Linux kernel will not forward [[Protocols/IP|IP]] packets (i.e. will not NAT).

This is overridden like:

{{{
#works until reboot
sudo sh -c 'echo 1 > /proc/sys/net/ipv4/ip_forward'

#permanently
sudo sh -c 'echo "net.ipv4.ip_forward = 1" >> /etc/sysctl.conf'
}}}

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== Address ==



=== DHCP ===



=== Ports ===

Ports 1 through 1024 are '''privileged''' and can only be bound by root processes.

To adjust this range (i.e. to lower the privileged range and allow a non-root process use of port 80), try:

{{{
#works until reboot
sudo sh -c "echo 80 > /proc/sys/net/ipv4/ip_unprivileged_port_start"

#permanent
sudo sh -c 'echo "net.ipv4.ip_unprivileged_port_start=80" >> /etc/sysctl.conf'
}}}

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== Firewalls ==

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== Unix Sockets ==

Linux offers a file-like object that can act like TCP/IP sockets for inter-process communication. These are known as '''Unix sockets'''.

Some advantages to a Unix socket over a traditional TCP/IP socket are:

 * as first class file-like objects, Unix sockets obey file permissions
 * Unix sockets are only addressable on the local file system, mitigating some security concerns
 * because there is no routing beyond filesystem lookups, Unix sockets ''can'' be faster



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CategoryRicottone