Multiple Loopback Interfaces

[John Chludzinski]

Both 127.0.0.7 and 127.0.0.10 exist in /etc/hosts for the client apps to
use when connecting to the server.    The clients use both
gethostbyname() and getservbyname() for connecting.  Currently, there
are *no* multiple loopback interfaces defined.  

I wrote my own example TCP socket code to test the set up and found
problems.

Without defining multiple loopback interfaces using 127.0.0.7 and
127.0.0.10, are 127.0.0.7 and 127.0.0.10 simply the same interface?

BTW, this is code I inherited.

---John


On Thu, Aug 29, 2013, at 06:49 AM, Reindl Harald wrote:
> BTW:
> 
> try to ping 127.0.0.1, 127.0.0.2, 127.0.0.3............
> 
> here they are pingable as default
> 
> the instruction below if only needed if the application
> checks that a configured IP exists via ifconfig or lookalike
> 
> Am 29.08.2013 15:46, schrieb Reindl Harald:
> > Am 29.08.2013 15:38, schrieb John Chludzinski:
> >> I need to used multiple loopback addresses (interfaces) for an server
> >> application that communicates with multiple clients running on the same
> >> machine.  Since a loopback interface short circuits the network stack
> >> (looping back in the IP layer) it is a more efficient means of
> >> communication, hence better for my purpose.
> >>
> >> How do I define multiple loopback interfaces?
> >>
> >> BTW, I'm a newbie to this mailing mailing list.  Hopefully this is an
> >> appropriate question?
> > 
> > if you are running network.service it's trivial
> > NetworkManager -> no ida, i do not touch it
> > ___________________________________________
> > 
> > [root at rh:/etc/sysconfig/network-scripts]$ cat /etc/sysconfig/network-scripts/ifcfg-lo:1
> > DEVICE=lo:1
> > IPADDR=127.0.0.2
> > ONPARENT=yes
> > 
> > [root at rh:/etc/sysconfig/network-scripts]$ ifup lo:1
> > 
> > [root at rh:/etc/sysconfig/network-scripts]$ ifconfig lo:1
> > lo:1: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
> >         inet 127.0.0.2  netmask 255.0.0.0
> >         loop  txqueuelen 0  (Lokale Schleife)
> > 
> > [root at rh:/etc/sysconfig/network-scripts]$ ping 127.0.0.2
> > PING 127.0.0.2 (127.0.0.2) 56(84) bytes of data.
> > 64 bytes from 127.0.0.2: icmp_seq=1 ttl=50 time=0.056 ms
> > ___________________________________________
> > 
> > that's the "lo" config shipped with Fedora
> > 
> > [root at rh:/etc/sysconfig/network-scripts]$ cat /etc/sysconfig/network-scripts/ifcfg-lo
> > DEVICE=lo
> > IPADDR=127.0.0.1
> > NETMASK=255.0.0.0
> > NETWORK=127.0.0.0
> > # If you're having problems with gated making 127.0.0.0/8 a martian,
> > # you can change this to something else (255.255.255.255, for example)
> > BROADCAST=127.255.255.255
> > ONBOOT=yes
> > NAME=loopback
> 
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-- 
---
  John Chludzinski
  john-chludzinski at myopera.com