[GLLUG] IP Aliases and routing

Brad Fears brad@mtsdev.com
04 Nov 2002 07:55:12 -0500

I have a similar box, but with multiple NICs rather than aliases, and I
use the NAT functions of IPTABLES to route my packets to their
appropriate destination IPs.  As long as the OS doesn't know the
difference between aliases and physical interfaces, I'm pretty sure nat
would work for you too.

Regarding the server packages, most should have a configuration option
for binding to a specific IP.  I know at least Apache, OpenSSH, and most
FTP servers can bind themselves to a specific IP address or listen on
all addresses by default.

--Brad Fears

On Sat, 2002-11-02 at 10:48, Subba Rao wrote:
> Hello,
> We have a Linux PC which has only one NIC with several IP Aliased
> addresses.  The aliased addresses are on different subnets.  Th Linux PC
> is pretty much behaving like a router.  I can ping all the address from the
> actual gateway that is connected to the Linux PC.  All the typical servers
> (FTP, Telnet, SMTP, HTTP, Syslog etc.) are running on this Linux PC.
> One of the aliased addresses (S.S.S.S) is serving as the syslog server for the gateway.
> When I watch the traffic using tcpdump,  the syslog packet makes it to the Linux PC but returned
> back (or dropped) because it cannot route it to S.S.S.S.
> I have 2 questions for this setup.
> 1. How do I route the packets on the Linux PC to it's alias address S.S.S.S?
> 2. Do the Linux servers (FTP,Telnet,SMTP,Syslog.....etc) bind to the actual interface address?
>     Or they attached to the IP Aliases as well?
> Thank you in advance for any help.
> Subba Rao
> sailorn@attglobal.net
> 2002-11-02
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