Proper Layout of /etc/hosts

itgl72 · 04-22-2005, 10:51 AM

I know this is a basic topic, and I have set these up many a time in simple environements and gotten the machine to work but I wanted to ask the forum about this question since I have read several help files online that have not really NAILED DOWN my question on /etc/hosts in a way in which I may want to use it.

I'm looking for the best practice in setting up the /etc/hosts for a linux box called "linuxserv" with an internal domain of abc.com and external domain of xyz.com.

Heres how I set up a basic system, IS IT WRONG TO GIVE IT TWO NAMES THAT POINT TO 127.0.0.1?

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
127.0.0.1 linuxserv.abc.com linuxserv

What about adding the internal IP address of the system like so, DOES THE FORMAT BELOW LOOK ACCEPTABLE?

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
127.0.0.1 linuxserv.abc.com linuxserv
192.168.1.2 linuxserv.abc.com linuxserv

Now lets say linuxserv also had a second network interface that links to the external network. What about adding the external IP address of the system like so, DOES THE FORMAT BELOW LOOK ACCEPTABLE?

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
127.0.0.1 linuxserv.abc.com linuxserv
192.168.1.2 linuxserv.abc.com linuxserv
234.X.X.X linuxserv.xyz.com linuxserv

What would make any of these unacceptable, or wrong in a best practice environement?

lugoteehalt · 04-22-2005, 11:33 AM

Quote:

#lugo The next line is all that was in the file. I am commenting it out.
#127.0.0.1 debian localhost
#
#lugo Put in next block to try to get networking.
127.0.0.1 localhost
192.168.1.1 debian.domain.org debian
192.168.1.2 apricot.domain.org apricot

Don't know if that any help, it's my file. It's for computer 1, debian, on a two computer network. The other computer is apricot.domain.org. You may put what you want for domain.org.link. It's a Debian system.

itgl72 · 04-25-2005, 08:22 AM

That did not really clear up my question. I'm looking for someone to reply with information regarding my setup posted above. I understand the basics but wanted to get a better grasp of the hosts file and its formats.

jschiwal · 04-25-2005, 09:05 AM

127.0.0.1 linuxserv.abc.com linuxserv
192.168.1.2 linuxserv.abc.com linuxserv
234.X.X.X linuxserv.xyz.com linuxserv

I believe that these lines would cause a problem. One thing that is sometimes done is to block access to a certain website by making its IP address 127.0.0.1 in the hosts file.

127.0.0.1 localhost localhost.localdomain
127.0.0.1 www.crackerland.com

That is assuming that /etc/hosts is searched first. That is true if a line in your host.conf is:
order hosts,bind

PTrenholme · 04-25-2005, 09:25 AM

Here's the first few lines of my primary /etc/hosts file:

Code:

$ cat /mnt/fc3/etc/hosts | more
90.0.0.4        tss-4   TSS-4
90.0.0.3        tss-3   TSS-3
90.0.0.2        tss-2   TSS-2
90.0.0.1        tss-1   TSS-1
127.0.0.1       localhost.localdomain   localhost
127.0.0.1       view.atdmt.com
127.0.0.1       clk.atdmt.com
127.0.0.1       nytmembercenter.112.2o7.net
127.0.0.1       promotions.real.com
127.0.0.1       media.fastclick.net

Note the first five lines: They are each assigning two names to the specified address. (The 90.0.0.* lines are for our internal [i.e., "home"] network. Our firewall used 90.0.0.* for internal networks, and M$ seems to prefer uppercase names for NETBIOS, which one of the family's systems is using.)