[CentOS] need help on second Ethernet port (eth1) point to point connect

Wed Aug 29 15:49:47 UTC 2007
Robert Moskowitz <rgm at htt-consult.com>


mcclnx mcc wrote:
> I have two DELL servers with two Ethernet ports in it.
>  Bith servers have CENTOS 4.5 installed.  First
> Ethernet port connect to public Ethernet line and work
> correctly.  Second Ethernet port I connect
> point-to-point as private Ethernet (cable direct
> connect without router or switch).  Private Ethernet
> use IP asddress 1.1.1.1 and 1.1.1.2.
>   
Take a quick look at RFC 1918 for priviate addresses to use (I am a 
co-author of that RFC).

Advice:

If you use addresses from the 192.168 range, avoid the nets: 
192.168.0.0, 192.168.1.0, 192.168.2.0, and 192.168.100.0  These are 
commonly used by various 'appliances'.  Choose something 'wierd' like 
192.168.49.0 (or some other prime number less than 255).  Though I tend 
to use 192.168.64.0, 192.168.96.0, or 192.168.128.0

Also avoid the 172.16 and 10. ranges.  These are commonly used in 
Company internal private networks, and if you want to 'VPN' to them, it 
can cause unwanted results (like it won't work).

This is general advice to anyone using private addresses for small 
usages (from a person that has taken more flak on private addresses and 
NAT than you probably care to deal with; I 'caused it').
> I check "ifconfig -a" and both eth0 and eth1 are up
> and active.  when I tried to ping another server use
> second port (private) and no response.  Does anything
> I configure wrong?
>
> Thanks.
>
> ========   info   ===  
>
>  %ifconfig -a
> eth0      Link encap:Ethernet  HWaddr
> 00:08:74:EA:54:64  
>           inet addr:172.29.86.15  Bcast:172.29.85.255 
> Mask:255.255.255.0
>           inet6 addr: fe80::208:74ff:feea:5464/64
> Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500 
> Metric:1
>           RX packets:471 errors:0 dropped:0 overruns:0
> frame:0
>           TX packets:91 errors:0 dropped:0 overruns:0
> carrier:0
>           collisions:0 txqueuelen:0 
>           RX bytes:65669 (64.1 KiB)  TX bytes:11847
> (11.5 KiB)
>
> eth1      Link encap:Ethernet  HWaddr
> 00:0E:2E:C8:B9:80  
>           inet addr:1.1.1.1  Bcast:1.1.1.255 
> 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)
>           Interrupt:18 Base address:0x4c00 
>
> %ping 1.1.1.2
> PING 1.1.1.2 (1.1.1.2) 56(84) bytes of data.
> >From 1.1.1.1 icmp_seq=1 Destination Host Unreachable
> >From 1.1.1.1 icmp_seq=2 Destination Host Unreachable
> >From 1.1.1.1 icmp_seq=3 Destination Host Unreachable
>
> --- 1.1.1.2 ping statistics ---
> 4 packets transmitted, 0 received, +3 errors, 100%
> packet loss, time 3015ms
> , pipe 3
>
>
> %telnet 1.1.1.2
> Trying 1.1.1.2...
> telnet: connect to address 1.1.1.2: No route to host
>
>
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