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user10178
Asked: 2009-09-15 07:56:09 +0800 CST

Is it possible to alias a hostname in Linux?

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Is it possible to alias a hostname in Linux?

It has been asked by jmillikin at various Ubuntu forums as follows:

Is it possible to create a hostname alias? Sort of like /etc/hosts, but with other hostnames rather than IP addresses. So that with some file like this, you could ping "fakehost1", and it would be re-mapped to "realhost", and then "realhost" would be resolved to an IP address.

# Real host        # Aliases
realhost           fakehost1 fakehost2 fakehost3

Somebody has answered about ssh, but not about ping, etc. My main purpose is to use it as an alias for a Subversion server. In my case, realhost is under a dynamic IP address. So, the "/etc/hosts" alias doesn't work. I want to access my Subversion server as svn://my_svnserver/my_repos instead of svn://realhost/my_repos.

linux

7 Answers

  1. For those who don't have an account on the forums (or don't wish to login):

    if your main issue is not to ping but to ssh, you can create/edit your ~/.ssh/config adding lines like these:

    Host fakehost1
  Hostname real-hostname

Host fakehost2
  Hostname real-hostname2

Host fakehost3
  Hostname real-hostname3
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  2. Linux supports aliasing by setting the HOSTALIASES env variable.

    echo "fakehost realhost" > /etc/host.aliases
echo "export HOSTALIASES=/etc/host.aliases" >> /etc/profile
. /etc/profile

    then you can 

    ping fakehost

    N.B. ping requires you to set this up as root, but you can do it as any user for any application that runs as that user. ping suids to root.

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  3. You can setup this on your DNS server, CNAME records allow a machine to be known by more than one hostname. So add CNAME records to your DNS server like that : 

    
fakehost1 IN CNAME realhost 
fakehost2 IN CNAME realhost 
fakehost3 IN CNAME realhost

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  4. I often do this with environment variables. I know this only works for the command line, but it is where I am most often craving hostname aliases (I worked with several supercomputer accounts, all with long URLs). Here's an example, if you're using BASH. In ~/.bashrc:

    export fakehost="long.ass.annoying.url.org"

    then, in a fresh shell:

    ssh christopher@$fakehost

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  5. The only way this can be done is if you have your own local dns server.

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  6. You'll need an dyndns server that will map your current IP address to a hostname. You'll tell this server about your current IP address whenever you login, and it will update your hostname record.

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  7. The use of /etc/hosts.aliases is a standard feature of the bind resolver libraries. It's more robust than adding entries to /etc/hosts and can be used if you can not add CNAMES to your DNS (don't have access to it).

    In general the best practice is to use CNAMES in the DNS with appropriate SEARCH defined in /etc/resolv.conf.

    Updating /etc/hosts is not very robust as entries have to be kept in sync with IP changes. This only really works on a small scale or when you are using a name service to distribute the hosts map (eg via ldap).

    Another solution may be DNSMasq http://en.wikipedia.org/wiki/Dnsmasq

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