routing problem (RH7.1)

routing problem (RH7.1)

Post by Ochre6 » Fri, 06 Jul 2001 00:11:11



my linux box is my gateway to the internet via my cable modem.

My modem-side NIC gets an IP OK via DHCP from the cable provider, and I can
ftp to its DNS server, but I can't ping anywhere (either IP or name,
although names are being resolved OK)

after installion, route shows:

Destination                Gateway            Genmask                Iface
192.168.0.0            0.0.0.0                255.255.255.0        eth1
144.132.240.0        0.0.0.0                255.255.240.0        eth0
127.0.0.0                0.0.0.0                255.0.0.0                lo
0.0.0.0                    144.132.240.1    0.0.0.0                    eth0

give the .240. genmask for the cable-side network, do these multiple class c
nets have something to do with my problem?

 
 
 

routing problem (RH7.1)

Post by Ken DeRoch » Fri, 06 Jul 2001 01:07:15


144.132.240.0        0.0.0.0                255.255.240.0        eth0
0.0.0.0                    144.132.240.1    0.0.0.0    ^^^           eth0
Quote:>                                            ^^^

It seems to me, that with this subnet mask, the 144.132.240.1 ip would not
be a valid host ip with above subnet. Perhaps subnetmask should be
255.255.255.0

give the .240. genmask for the cable-side network, do these multiple class c

Quote:> nets have something to do with my problem?

144.132.x.x is class 'B' btw.

I hope this helps.
---regards: Ken


Quote:> my linux box is my gateway to the internet via my cable modem.

> My modem-side NIC gets an IP OK via DHCP from the cable provider, and I
can
> ftp to its DNS server, but I can't ping anywhere (either IP or name,
> although names are being resolved OK)

> after installion, route shows:

> Destination                Gateway            Genmask                Iface
> 192.168.0.0            0.0.0.0                255.255.255.0        eth1
> 144.132.240.0        0.0.0.0                255.255.240.0        eth0
> 127.0.0.0                0.0.0.0                255.0.0.0
lo
> 0.0.0.0                    144.132.240.1    0.0.0.0
eth0

> give the .240. genmask for the cable-side network, do these multiple class
c
> nets have something to do with my problem?


 
 
 

routing problem (RH7.1)

Post by Trygve Selme » Fri, 06 Jul 2001 01:17:33



> 144.132.240.0        0.0.0.0                255.255.240.0        eth0
> 0.0.0.0                    144.132.240.1    0.0.0.0    ^^^           eth0
> >                                            ^^^
> It seems to me, that with this subnet mask, the 144.132.240.1 ip would not
> be a valid host ip with above subnet. Perhaps subnetmask should be
> 255.255.255.0

This is a perfectly legal entry for a default gateway. Check out your
own routing table :-)

        Trygve.

 
 
 

routing problem (RH7.1)

Post by Ken DeRoch » Fri, 06 Jul 2001 01:39:33




> > 144.132.240.0        0.0.0.0                255.255.240.0        eth0
> > 0.0.0.0                    144.132.240.1    0.0.0.0    ^^^
eth0
> > >                                            ^^^
> > It seems to me, that with this subnet mask, the 144.132.240.1 ip would
not
> > be a valid host ip with above subnet. Perhaps subnetmask should be
> > 255.255.255.0

> This is a perfectly legal entry for a default gateway. Check out your
> own routing table :-)

> Trygve.

The default gateway entry looks fine, it's the above subnet mask entry for
that network, that seems to
make the gw ip 'out of range' for that subnet.
the routing table on my own gateway:

Kernel IP routing table
Destination     Gateway         Genmask                Flags Metric Ref
Use Iface
192.168.2.1     192.168.1.1     255.255.255.255 UGH   0      0        0
eth1
192.168.1.10    0.0.0.0            255.255.255.255 UH      0      0        0
eth1
192.168.3.0     192.168.1.1     255.255.255.0     UG      0      0        0
eth1
65.32.59.0       0.0.0.0             255.255.255.0     U         0      0
0       eth0
192.168.2.0     192.168.1.1     255.255.255.0     UG      0      0        0
eth1
192.168.1.0     192.168.1.1     255.255.255.0     UG      0      0        0
eth1
192.168.1.0     0.0.0.0             255.255.255.0     U         0      0
0       eth1
127.0.0.0         0.0.0.0             255.0.0.0             U         0
0        0       lo
0.0.0.0             65.32.59.1       0.0.0.0                 UG      0
0        0       eth0

 
 
 

routing problem (RH7.1)

Post by M. Buchenried » Fri, 06 Jul 2001 01:29:08



>144.132.240.0        0.0.0.0                255.255.240.0        eth0
>0.0.0.0                    144.132.240.1    0.0.0.0    ^^^           eth0
>>                                            ^^^
>It seems to me, that with this subnet mask, the 144.132.240.1 ip would not
>be a valid host ip with above subnet.

[...]

Nope, that's perfectly fine. The network spans from
144.132.240.0 to 144.132.254.255.

That doesn't mean, however, that this routing information is
correct.

What does "ifconfig" say about your NICs settings?

Michael

--

          Lumber Cartel Unit #456 (TINLC) & Official Netscum
    Note: If you want me to send you email, don't munge your address.

 
 
 

routing problem (RH7.1)

Post by Ken DeRoch » Fri, 06 Jul 2001 06:21:40




> >144.132.240.0        0.0.0.0                255.255.240.0        eth0
> >0.0.0.0                    144.132.240.1    0.0.0.0    ^^^           eth0
> >>                                            ^^^
> >It seems to me, that with this subnet mask, the 144.132.240.1 ip would
not
> >be a valid host ip with above subnet.

> [...]

> Nope, that's perfectly fine. The network spans from
> 144.132.240.0 to 144.132.254.255.

> That doesn't mean, however, that this routing information is
> correct.

> What does "ifconfig" say about your NICs settings?

> Michael

> --

>           Lumber Cartel Unit #456 (TINLC) & Official Netscum
>     Note: If you want me to send you email, don't munge your address.

I beg to differ sir. the way I see it is as follows:
address 144.132.240.0 (a class B) without subnetting has a network address
of 144.132.0.0
Default subnet mask is 255.255.0.0
 inserting subnet mask of 255.255.240.0 to the 144.132.0.0 network results
in valid subnets
beginning with:
144.132.16.0
144.132.32.0
144.132.48.0
144.132.64.0
144.132.80.0
144.132.96.0
144.132.112.0
144.132.128.0
144.132.144.0
144.132.160.0
144.132.176.0
144.132.192.0
144.132.224.0             144.132.239.254 would be the last valid host id
with this subnet scheme.

144.132.240.0 (and 144.132.241.0 etc.) would not be a valid address in such
a network/subnetwork.

lastly, a 255.255.240.0 netmask on a class B network provides for 4094 hosts
per subnet.
This seems illogical on a cable modem network, as they typically function as
an IEEE 802.3 CSMA/CD Ethernet, such a large number of hosts would make for
a massive collision domain (without many switches, bridges, routers etc.)
and thus would have poor, if any useable bandwidth.
 ---Regards:  Ken

 
 
 

routing problem (RH7.1)

Post by Trygve Selme » Fri, 06 Jul 2001 07:09:52



> I beg to differ sir. the way I see it is as follows:
> address 144.132.240.0 (a class B) without subnetting has a network address
> of 144.132.0.0
> Default subnet mask is 255.255.0.0
>  inserting subnet mask of 255.255.240.0 to the 144.132.0.0 network results
> in valid subnets
> beginning with:
> 144.132.16.0
> 144.132.32.0
> [snip]
> 144.132.192.0
> 144.132.224.0             144.132.239.254 would be the last valid host id
> with this subnet scheme.

> 144.132.240.0 (and 144.132.241.0 etc.) would not be a valid address in such
> a network/subnetwork.

I'm sorry, Ken, but the golden days with class A, B, and C are gone.
What you have is a /20 network (or, if you like, a subnetwork from an
old B-class address range). You missed out by deleting the first and
last entry of your table, namely networks 144.132.0.0/20 and
144.132.240.0/20. They are perfectly legal!

Your list should read (mask is 255.255.240.0):
144.132.0.0/20, hosts 144.132.0.1 - 144.132.15.254
144.132.16.0/20, hosts 144.132.16.1 - 144.132.31.254
...
144.132.224.0/20, hosts 144.132.224.1 - 144.132.239.254
144.132.240.0/20, hosts 144.132.240.1 - 144.132.255.254

        Trygve.

 
 
 

routing problem (RH7.1)

Post by Ochre6 » Fri, 06 Jul 2001 08:44:35


it says I have an IP of 144.132.242.XX



> >144.132.240.0        0.0.0.0                255.255.240.0        eth0
> >0.0.0.0                    144.132.240.1    0.0.0.0    ^^^           eth0
> >>                                            ^^^
> >It seems to me, that with this subnet mask, the 144.132.240.1 ip would
not
> >be a valid host ip with above subnet.

> [...]

> Nope, that's perfectly fine. The network spans from
> 144.132.240.0 to 144.132.254.255.

> That doesn't mean, however, that this routing information is
> correct.

> What does "ifconfig" say about your NICs settings?

> Michael

> --

>           Lumber Cartel Unit #456 (TINLC) & Official Netscum
>     Note: If you want me to send you email, don't munge your address.

 
 
 

routing problem (RH7.1)

Post by Dean Thompso » Fri, 06 Jul 2001 12:54:11


Hi!,

Quote:> my linux box is my gateway to the internet via my cable modem.

> My modem-side NIC gets an IP OK via DHCP from the cable provider, and I can
> ftp to its DNS server, but I can't ping anywhere (either IP or name,
> although names are being resolved OK)

> after installion, route shows:

> Destination                Gateway            Genmask                Iface
> 192.168.0.0            0.0.0.0                255.255.255.0        eth1
> 144.132.240.0        0.0.0.0                255.255.240.0        eth0
> 127.0.0.0                0.0.0.0                255.0.0.0                lo
> 0.0.0.0                    144.132.240.1    0.0.0.0                    eth0

> give the .240. genmask for the cable-side network, do these multiple class
> c nets have something to do with my problem?

If your TCP/IP is working without a problem, then it would suggest that your
routing is up to a point where it is working.  Check to make sure that the
firewall is not blocking ICMP packets or that your service provider isn't
squashing ICMP above you.

See ya

Dean Thompson

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routing problem (RH7.1)

Post by M. Buchenried » Fri, 06 Jul 2001 14:52:14



>it says I have an IP of 144.132.242.XX

[...]

That's fine.

Can you ping the gateway?

Michael

--

          Lumber Cartel Unit #456 (TINLC) & Official Netscum
    Note: If you want me to send you email, don't munge your address.

 
 
 

routing problem (RH7.1)

Post by M. Buchenried » Fri, 06 Jul 2001 14:47:33


[...]

Quote:>I beg to differ sir. the way I see it is as follows:
>address 144.132.240.0 (a class B) without subnetting has a network address
>of 144.132.0.0
>Default subnet mask is 255.255.0.0

Right.

Quote:> inserting subnet mask of 255.255.240.0 to the 144.132.0.0 network results
>in valid subnets
>beginning with:
>144.132.16.0

Wrong.

The first subnet will be
N.N.0.0, N.N.0-15.N , N.N.15.255

and the last one
N.N.240.0, N.N.240-254.N, N.N.254.255

A /16 netmask creates 16 valid and useable 4-bit subnets.

Please read RFC 1878. What you're thinking about is classful
networking, which has been overthrown 8 years ago. These are the
days of CIDR.

[...]

Quote:>144.132.240.0 (and 144.132.241.0 etc.) would not be a valid address in such
>a network/subnetwork.

Nope. It's a perfectly valid subnet.

Quote:>lastly, a 255.255.240.0 netmask on a class B network provides for 4094 hosts
>per subnet.

Right.

Quote:>This seems illogical on a cable modem network,

[...]

Agreed, but that's the cable network company's decision.

Michael
--

          Lumber Cartel Unit #456 (TINLC) & Official Netscum
    Note: If you want me to send you email, don't munge your address.

 
 
 

routing problem (RH7.1)

Post by Ochre6 » Fri, 06 Jul 2001 23:29:00


not as yet, but my (rapid) learning curve leads me to believe that the
problem lies in the firewall rather than the route since I'm resolving names
from the DNS OK, but my ICMP packets seem to be getting squashed.

most informative discussion on nets/subnets, lads.  thanks for the tutorial.



> >it says I have an IP of 144.132.242.XX

> [...]

> That's fine.

> Can you ping the gateway?

> Michael

> --

>           Lumber Cartel Unit #456 (TINLC) & Official Netscum
>     Note: If you want me to send you email, don't munge your address.

 
 
 

routing problem (RH7.1)

Post by Ken DeRoch » Sun, 08 Jul 2001 07:04:16


Did you ever get your gateway going?


> not as yet, but my (rapid) learning curve leads me to believe that the
> problem lies in the firewall rather than the route since I'm resolving
names
> from the DNS OK, but my ICMP packets seem to be getting squashed.

> most informative discussion on nets/subnets, lads.  thanks for the
tutorial.




> > >it says I have an IP of 144.132.242.XX

> > [...]

> > That's fine.

> > Can you ping the gateway?

> > Michael

> > --


http://www.muc.de/~mibu

- Show quoted text -

Quote:> >           Lumber Cartel Unit #456 (TINLC) & Official Netscum
> >     Note: If you want me to send you email, don't munge your address.

 
 
 

1. RH7 routing problem

Hello folks,

 I'm having a nightmare of a time geting routing to work right on my
RH7 box.  Here's the story:  I have a single 3c509-TP0 PnP cart (eth0)
that, after some careful config'ing, seems to load up fine.  I added
routes for the eth0 interface, as well as the default gateway (see
below).  I can ping my card, but when i try to ping outside, I get
the "network unreachable" error.  The funny thing is, I can see my LAN
light on my DSL modem blinks (it lit solid in windows) with each
packet.  Please note, this is not the DATA light, so it seems that the
packet make it to the modem but can't find anywhere to go after
that?!?  Below is some of my data config, any help would be greatly
appreciated!

dmesg | tail:
Linux agpgart interface v0.99 (c) Jeff Hartmann
agpgart: Maximum main memory to use for agp memory: 28M
agpgart: Detected Intel 440BX chipset

eth0: 3c509 at 0x300 tag 1, 10baseT port, address  00 20 af cf 86 2e,
IRQ 10.

eth0: Setting Rx mode to 1 addresses.
hdb: ATAPI 32X CD-ROM drive, 128kB Cache
Uniform CD-ROM driver Revision: 3.10
hdc: ATAPI 6X CD-ROM CD-R/RW drive, 768kB Cache

ifconfig:
eth0      Link encap:Ethernet  HWaddr 00:20:AF:CF:86:2E
          inet addr:XXX.YY.91.212  Bcast:XXX.YY.95.255
Mask:255.255.248.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          Interrupt:3 Base address:0x300

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:3924  Metric:1
          RX packets:248 errors:0 dropped:0 overruns:0 frame:0
          TX packets:248 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0

route:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
XXX.YY.88.0     *               255.255.248.0   U     0      0        0
eth0
127.0.0.0       *               255.0.0.0       U     0      0        0
lo
default         XXX.YY.88.1     0.0.0.0         UG    1      0        0
eth0

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