Why can't I route to some sites from my MacBook Pro that I can see from my iPad?

Question

Possible Duplicate:
Mac OS X traceroute not even reaching router gateway

I am on M1 Cable (residential) broadband in Singapore.

I have an intermittent problem routing to some sites from my MacBook Pro—often Google-related sites (arduino.googlecode.com and ajax.googleapis.com right now, but sometimes even gmail.com.) This prevents StackExchange chat from working, for instance. Funny thing is, my iPad can route to those sites and they're on the same wireless network! I can ping the sites, but not traceroute to them which I find odd.

That I can get through via the iPad implies the problem is with the MBP. In any case, calling M1 support is... not helpful.

I get the same behaviour when I bypass the Airport Express entirely and plug the MBP directly into the cable modem. Can anybody explain a) how this is even possible and b) how to fix it?

mella:~ ratkins$ ping ajax.googleapis.com
PING googleapis.l.google.com (209.85.132.95): 56 data bytes
64 bytes from 209.85.132.95: icmp_seq=0 ttl=50 time=11.488 ms
64 bytes from 209.85.132.95: icmp_seq=1 ttl=53 time=13.012 ms
64 bytes from 209.85.132.95: icmp_seq=2 ttl=53 time=13.048 ms
^C
--- googleapis.l.google.com ping statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 11.488/12.516/13.048/0.727 ms
mella:~ ratkins$ traceroute ajax.googleapis.com
traceroute to googleapis.l.google.com (209.85.132.95), 64 hops max, 52 byte packets
traceroute: sendto: No route to host
 1 traceroute: wrote googleapis.l.google.com 52 chars, ret=-1
 *traceroute: sendto: No route to host
traceroute: wrote googleapis.l.google.com 52 chars, ret=-1
^C
mella:~ ratkins$

The traceroute from the iPad goes (and I'm copying this by hand):

10.0.1.1
119.56.34.1
172.20.8.222
172.31.253.11
202.65.245.1
202.65.245.142
209.85.243.156
72.14.233.145
209.85.132.82

From the MBP, I can't traceroute to any of the IPs from 172.20.8.222 onwards.

Answer 1

Turns out this was the answer (tl;dr, nuke Peerguardian from orbit.)

Answer 2

Firstly, the traceroute: sendto: No route to host message is your primary clue. Your MacBook Pro's network configuration isn't fully functional. Perhaps the MacBook is configured with some static settings that overide the settings that are obtainable by DHCP from your cable broadband modem or router?

Secondly MacBooks and iPads run different operating systems. It is possible that this has some bearing on the problem. Either in the way these devices pick up wireless settings or in the way tracert/traceroute work (normally they use ICMP protocol but some variants use TCP - it is possible that ICMP is blocked at some router/firewall)

On the Macbook Pro, can you get it to display it's network settings - chiefly default gateway and DNS servers? E.g. ifconfig -a

If you can see the equivalent informatio on the iPad - look for differences.