simple networking questions

simple networking questions

Post by Pet » Fri, 27 Aug 1999 04:00:00



dear all,

if a machine has both an ethernet connection (say, DSL) and a modem PPP
connection at the same time, which connection gets preference for things
like telnet and netscape?

i'm trying to get my DSL connection configured, but the PPP connection is
my best resource (usenet, dejanews...), so i'd like to keep that connection
open.   is there a way of trying to telnet or netscape by using the ethernet
instead of the PPP connection?  the idea is to test the DSL connection
while keeping PPP open so i can continue to look for resources to help me.

also, if your system is connected via ethernet (say, DSL again) where does
gateway and subnet mask information go?

how do you tell the ethernet card what your static IP address is?  is that
the role of ifconfig?  

pete

 
 
 

simple networking questions

Post by rm.. » Fri, 27 Aug 1999 04:00:00


Quote:>if a machine has both an ethernet connection (say, DSL) and a modem PPP
>connection at the same time, which connection gets preference for things
>like telnet and netscape?

Preference has nothing to do with the interfaces, per se.  It's all about
the routes.  If you are simply trying to use your ppp interface
while configuring your dsl via ethernet, make sure your default
route is pointed at our ppp device.

your routes should look something like the following for above situation:

# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
172.16.0.254    0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
10.0.0.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        0 lo
0.0.0.0         0.0.0.0         0.0.0.0         U     0      0        0 ppp0

So your connect routes (10.0.0.0 in this case) will go via your ethernet
device.  Everything else will go out your ppp device.

Then, when you wanna test your dsl connection, add a route for some
internet address you know is active (let's say www.yahoo.com for grins).

Ping it via your ppp interface, make sure it's there.

Name:    www.yahoo.com
Addresses:  204.71.200.74, 204.71.200.67, 204.71.200.75, 204.71.200.68

# ping 204.71.200.74
PING 204.71.200.74 (204.71.200.74): 56 data bytes
64 bytes from 204.71.200.74: icmp_seq=0 ttl=247 time=92.7 ms
64 bytes from 204.71.200.74: icmp_seq=1 ttl=247 time=177.5 ms

# route add -host 204.71.200.74 dev eth0

which will make your route table look something like:

# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
204.71.200.74   0.0.0.0         255.255.255.255 UH    0      0        0 eth0
172.16.0.254    0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
10.0.0.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        0 lo
0.0.0.0         0.0.0.0         0.0.0.0         U     0      0        0 ppp0

Then traceroute to 204.71.200.74 to see it gets through your dsl connection.
If it does, change default to your ethernet and have fun...If it doesn't
work, rinse and repeat.

Quote:>also, if your system is connected via ethernet (say, DSL again) where does
>gateway and subnet mask information go?

Depends on your distribution.  On redhat based distro's, /etc/sysconfig/network

Quote:>how do you tell the ethernet card what your static IP address is?  is that
>the role of ifconfig?  

If config stands for "Interface Config."  This is the utility you to config
your interface.

# ifconfig eth0 10.0.0.1 netmask 255.255.255.0 broadcast 10.0.0.255 up

Type "man ifconfig" and "man route" for more info.

R. Marc

 
 
 

simple networking questions

Post by Thomas Kaeme » Fri, 27 Aug 1999 04:00:00



Quote:

> # route add -host 204.71.200.74 dev eth0

With this route you will only get a time out, because this host isn't a
part of the subnet eth0 is connected. You should add the gateway to your
ISP with this line :
 # route add -host 204.71.200.74 gw x.x.x.x eth0

CU Thomas

 
 
 

simple networking questions

Post by rm.. » Fri, 27 Aug 1999 04:00:00




>> # route add -host 204.71.200.74 dev eth0

>With this route you will only get a time out, because this host isn't a
>part of the subnet eth0 is connected. You should add the gateway to your
>ISP with this line :
> # route add -host 204.71.200.74 gw x.x.x.x eth0

Whoops.  My mistake.  I made a presumption I didn't include in that
you have a gateway route for ethernet.  It's also good to note that my
example uses private IP space which you'll undoubtedly exchange for
real IP's that your ISP(s) give you or dynamically assign to you.

R. Marc

 
 
 

1. simple network question

hi!

do I have to adjust my routing tables, even if the network I want to set up
only consists of two workstations (one linux, one freebsd)? or will changes
in rc.conf and /etc/hosts alone do the trick?

i just want to connect these two machines with each other, there are no
gateways, nothing, just 2 unix boxes with static addresses (192.168.1.1 and
2). what is required? the ethernet  cards were detetced and onfigured
without a problem.

thanx

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