[Novalug] stuck at reading route, traceroute

Walt Smith waltechmail@yahoo.com
Fri Dec 9 17:20:10 EST 2016



Hi,

Thought I'd better review fundamentals:

the routes as the packets leave my box 
and get out to the Internet:


On a ppp dialup, I show a route  and a traceroute
and a ifconfig below, hopefully readable on wide screen..

1. 
The route -n shows the gateway as 0.0.0.0, which I always
thought of as default going out.  However, some reading 
has told me that the * means there is No Gateway !!

But the default route below also shows no gateway.
Is destination 0.0.0.0 a special case ?  IF default is
by definition 0.0.0.0, where does the next packet go- 
i.e. which interface etc?

2.
Neither route nor traceroute  show the linux end at the modem
of the ppp0 IP number:  69.72.x.x which I assume to be at the 
dialup modem at my end.  It starts at the other end of the telco.

Aren' there interfaces ( even if ppp virtual ) between the lo
interface and the telco's access point end ?  does the 69.x.x
belong to the modem ?  or the serial port ?

3. why does the traceroute  in case 2 below show the telco's
access point as the first IF rather than the virtual ppp 69.72.x.x ?

4. And a validating Q:
in ifconfig below, would 209.163.x.x be considered a "gateway "
and the 69.x.x.x be the virtual ppp address at my end ?

thx,

Walt . . . .

----------------------

[root@CentOS68 etc]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
mgmt-apx01.bltm *               255.255.255.255 UH    0      0        0 ppp0
default         *               0.0.0.0         U     0      0        0 ppp0

[root@CentOS68 etc]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
209.163.113.81  0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
0.0.0.0         0.0.0.0         0.0.0.0         U     0      0        0 ppp0

[root@CentOS68 etc]# traceroute 69.72.61.28
traceroute to 69.72.61.28 (69.72.61.28), 30 hops max, 60 byte packets
 1  core-bltm-69-72-61-28.dynamic-dialup.coretel.net (69.72.61.28)  0.068 ms  0.019 ms  0.018 ms

[root@CentOS68 etc]# traceroute 209.163.113.81
traceroute to 209.163.113.81 (209.163.113.81), 30 hops max, 60 byte packets
 1  mgmt-apx01.bltm.coretel.net (209.163.113.81)  1210.309 ms  1210.215 ms  1212.207 ms
[root@CentOS68 etc]# traceroute sdf.org
traceroute to sdf.org (192.94.73.15), 30 hops max, 60 byte packets
 1  mgmt-apx01.bltm.coretel.net (209.163.113.81)  122.757 ms  137.267 ms  247.392 ms
 2  gw1-apx1.bltm.coretel.net (209.163.113.193)  213.304 ms gw2-apx1.bltm.coretel.net (209.163.113.197)  232.230 ms gw1-apx1.bltm.coretel.net (209.163.113.193)  247.196 ms
 3  jr1-balt-ge-0-0-9.qis.net (209.150.98.73)  232.163 ms  268.888 ms  287.851 ms




ppp0      Link encap:Point-to-Point Protocol  
          inet addr:69.72.61.236  P-t-P:209.163.113.81  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:596 errors:5 dropped:0 overruns:0 frame:0
          TX packets:618 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3 
          RX bytes:264368 (258.1 KiB)  TX bytes:64163 (62.6 KiB)



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