Preferred settings for /etc/hosts

NotionCommotion · 07-15-2013, 09:52 PM

I have a residential router connected to two CentOS servers and the Internet, and myDomain.com points to my router's public IP.

Is there anything else I should add to /etc/sysconfig/network?

What is the purpose of /etc/hosts, and giving my configuration, should I change it?

Thank you

PS. Don't know if it is relevant, but desktop communicates using wlan0 and laptop communicates using eth0.

Code:

[root@desktop ~]# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=desktop.myDomain.com

[root@desktop ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

[root@desktop ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 88:51:FB:51:DF:70
          inet addr:192.168.0.202  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

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:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

wlan0     Link encap:Ethernet  HWaddr B8:76:3F:69:31:95
          inet addr:192.168.0.104  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::ba76:3fff:fe69:3195/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:13547 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6620 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:2846258 (2.7 MiB)  TX bytes:1298853 (1.2 MiB)

[root@desktop ~]#

Code:

[root@laptop ~]# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=laptop.myDomain.com

[root@laptop ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

[root@laptop ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:1C:23:1E:8B:00
          inet addr:192.168.0.201  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::21c:23ff:fe1e:8b00/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:4042 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1454 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:324360 (316.7 KiB)  TX bytes:328752 (321.0 KiB)
          Interrupt:17

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:34 errors:0 dropped:0 overruns:0 frame:0
          TX packets:34 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2412 (2.3 KiB)  TX bytes:2412 (2.3 KiB)

virbr0    Link encap:Ethernet  HWaddr 52:54:00:12:38:1C
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

wlan0     Link encap:Ethernet  HWaddr 00:1E:4C:9A:95:AE
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

[root@laptop ~]#

frankbell · 07-15-2013, 10:36 PM

This wikipedia article gives a pretty good summary of the history and uses of a hosts file.

https://en.wikipedia.org/wiki/Hosts_(file)

The only essential entry in most contemporary uses is the loopback address (commonly 127.0.0.1).

If you want to use it to block internet redirects (as "ad.doubleclick.net") this link will help. I prefer this method to running adblock browser add-ons, because it uses minimal CPU cycles and is browser-independent.

NotionCommotion · 07-15-2013, 10:52 PM

Thanks Frank,

So, my /etc/hosts file lists a bunch of localhostX and localdomainX. Do I want to change any of these to desktop or laptop and myDomain.com?

PS. Anyone clicking the link, be sure to add a ) to the url.

frankbell · 07-15-2013, 11:44 PM

I would say that, if it's working, there's no reason to change anything.

If you want to test some new settings, be sure to save the original so you can restore it if necessary.

If you would like us to look at your hosts file, just post it, being sure to surround it with "code" tags, which become available when you click the "Go Advanced" button at the bottom of the quick reply window. Seeing the file, or at least a portion of it, would make it easier to answer your question.

Here's mine from Debian Wheezy:

Code:

~$ cat /etc/hosts
127.0.0.1 localhost
127.0.1.1 tuna.bell.org tuna.bell.org

# The following lines are desirable for IPv6 capable hosts
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts
127.0.0.1 tuna # added by Apache Friends XAMPP

bell.org is strictly internal to my home network and I name all my computers after denizens of the sea.

I'm not using IPv6, but Debian added that section, probably during the last dist-upgrade, because I know I didn't.