CentOS-6.6
We have a host that has multiple IPv4 addresses aliased to eth0. The
primary address is 216.185.71.x and the alias is 192.168.6.x.
This host connects to devices on both netblocks without problems.
Only default routing is used and it looks like this:
#ip route
192.168.6.0/24 dev eth0 proto kernel scope link src 192.168.6.x
216.185.71.0/24 dev eth0 proto kernel scope link src 216.185.71.x
169.254.0.0/16 dev eth0 scope link metric 1002
default via 192.168.6.1 dev eth0 src 192.168.6.x
default via 216.185.71.1 dev eth0
When the system connects to internal systems via ssh it uses the src
216.185.71.x for devices on that netblock and 192.168.6.x for devices
on the other.
The problem is that when we try to establish an ssh connection
off-site to another netblock altogether the host uses 192.168.6.x as
the source and the destination gets the public side IP address of our
gateway router as the point of origin due to masquerading.
I have solved this by explicitly binding ssh to the public ipv4 when
connecting using the --bind=216.185.71.x parameter. But I have two
questions I would like to find answers for
1. Why is ssh using the private IP in preference to the public IP when
connecting to off-site addresses?
2. How does one configure the routing table on network startup to
specifically detail the route particular addresses are supposed to
take?
For diagnosis here are the ifcfg scripts used for both interfaces:
DEVICE="eth0"
BOOTPROTO="static"
BROADCAST="216.185.71.255"
DNS1="216.185.71.33"
GATEWAY="216.185.71.1"
HWADDR="38:60:77:D5:AC:D8"
IPADDR="216.185.71.x"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
NETMASK="255.255.255.0"
NM_CONTROLLED="no"
ONBOOT="yes"
TYPE="Ethernet"
UUID="0202e615-ce93-4fe1-833a-c11259afb850"
DEVICE="eth0:192"
BOOTPROTO="static"
BROADCAST="192.168.6.255"
GATEWAY="192.168.6.1"
IPADDR="192.168.6.x"
NETMASK="255.255.255.0"
NM_CONTROLLED="no"
ONPARENT="yes"
TYPE="Ethernet"
--
*** E-Mail is NOT a SECURE channel ***
James B. Byrne mailto:ByrneJB@xxxxxxxxxxxxx
Harte & Lyne Limited http://www.harte-lyne.ca
9 Brockley Drive vox: +1 905 561 1241
Hamilton, Ontario fax: +1 905 561 0757
Canada L8E 3C3
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
