Question: I have been setting up my own server, and a lot of help documents refer to the 127.0.0.1 address. What is 127.0.0.1?
Answer: 127.0.0.1 is the standard ip address assigned to the lookback network interface in IPv4. Because it is a standard, all server should conform to it, and you should be able to access any open ports on your own server through that address. It is also known by the hostname “localhost”, and it is actually more common for documentation to use localhost just in case a server happens to use a different ip address.
If you are running Apache on a local machine, you can use 127.0.0.1 or localhost to access it through a web browser or other method. It is also used by MySQL, CUPS, and many other services, all using their own various ports. Even if no other network devices are setup on a Linux server, the “lo” loopback device should still be present. To find out information about it, you can type “ifconfig” from the command line. It should produce output that looks something like this:
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:49476 errors:0 dropped:0 overruns:0 frame:0
TX packets:49476 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:9790315 (9.7 MB) TX bytes:9790315 (9.7 MB)
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