[CentOS] outside ssh connection from two different ISP's

Mon Nov 10 22:38:27 UTC 2014
Jack Bailey <jack at internetguy.net>

On 11/10/2014 2:11 PM, Frank Cox wrote:
> I have both cable and dsl service.  The router attached to the cable service is 192.168.0.1 and the router attached to the dsl service is 192.168.0.254.  I determine which service my computers communicate through by setting the gateway assignment to either of those addresses and it just works.
>
> I can connect to my computers from the outside by port forwarding from my routers to the computer that I want to connect to.
>
> However, the outside ssh connection works only if the computer's gateway assignment matches the router that I'm connecting to.  I suspect that I have to set up some sort of routing assignment to tell the computer to reply to the gateway that the ssh connection request came in on if it doesn't match the current gateway assignment, but I have no idea how to do that.
>

I also have two ISPs at home.  I have a Peplink to manage this now, but 
before that I some commands in rc.local.  I had two networks and two 
NICs on my workstation.  This used to work on CentOS 6.

##############################
# symetric routing           #
##############################

NIC1=eth0
IP1=192.168.1.6
GW1=192.168.1.1
NET1=192.168.1.0/24

NIC2=eth1
IP2=192.168.2.6
GW2=192.168.2.1
NET2=192.168.2.0/24

DEFGW=$GW2

cat << EOF > /etc/iproute2/rt_tables
#
# reserved values
#
255     local
254     main
253     default
0       unspec
#
# local
#
#1      inr.ruhep

# symetric routing
101     T1
102     T2
EOF

# routing and default gateway for each interface
ip route add $NET1 dev $NIC1 src $IP1 table T1
ip route add default via $GW1 table T1
ip route add $NET2 dev $NIC2 src $IP2 table T2
ip route add default via $GW2 table T2

# regular routes
ip route add $NET1 dev $NIC1 src $IP1
ip route add $NET2 dev $NIC2 src $IP2

# preference for default route
route delete default
ip route add default via $DEFGW

# rules
ip rule add from $IP1 table T1
ip rule add from $IP2 table T2

# enable routing
echo 1 > /proc/sys/net/ipv4/ip_forward

Good luck,
Jack