[Tfug] A little help here sharing my cellmodem connection...?

[Jim March]

Guys,

I *finally* tonight got my new Verizon cellmodem working after (sigh)
losing my last one.  The new one fits in an Expresscard slot so the
good news is, more usable USB ports (yay).  It's a KPC680 card,
details on getting it to work are here in case anybody cares (the
solution has implications for at least some other cellmodems and
possibly Debian as well as Ubuntu):

http://ubuntuforums.org/showpost.php?p=5903831&postcount=9

I'm about to go on a month-long road trip monitoring the Maricopa
elections.  I'll be with somebody whose Windows lappy won't have a
cellmodem.  I want to share my cellmodem connection with my Ethernet
port using a cross-wired cat-5 cable straight to his box.  Here's my
ifconfig screen with WiFi turned off - it's an Intel that can't
broadcast well...

---
jim at critter:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:1d:09:4e:be:f3
          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:16

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:6904 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6904 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:369852 (369.8 KB)  TX bytes:369852 (369.8 KB)

ppp0      Link encap:Point-to-Point Protocol
          inet addr:75.211.217.176  P-t-P:66.174.217.64  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:10 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:741 (741.0 B)  TX bytes:534 (534.0 B)

jim at critter:~$
---

My Ethernet hardware is (per lspci):

---
09:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8040
PCI-E Fast Ethernet Controller (rev 12)
---

...and just in case I *can* re-broadcast under the Intel card, it's
the new A/B/G/B mini-PCI-express type:

---
0b:00.0 Network controller: Intel Corporation PRO/Wireless 4965 AG or
AGN Network Connection (rev 61)
---

I'm on Ubuntu Intrepid (Beta1) running Network Manager 7.  However, I
have some options: I also have the cellmodem card fully working with a
wvdial script, so I can either use it bypassing NM7 or I can rip out
Network Manager completely and swap in Wicd if I want to.  In fact I
think I'd prefer that as NM7 is in other ways a pest-ridden mess...

NM7 is supposed to have integrated "port sharing" but either I'm not
using it right or it's as buggy as an ant farm right now, as all
attempts to turn that on have caused NM7 to crash and not come back
until I reboot.  So I'm thinking I ought to do old-fashioned IP
tables, or use a firewall app of some sort.

Heeeelp?

Jim