There are probably lots of situation when this can happen, but this is a big mistery for me. Some tools can use the network just fine (wget, dig, apt-get, ...), but some tools are just failing (ping, traceroute, the browser, ...).
For example, I can download a file with wget
:
gonvaled@pegasus ~ » wget archive.ubuntu.com
--2014-10-02 10:52:34-- http://archive.ubuntu.com/
Resolving archive.ubuntu.com (archive.ubuntu.com)... 2001:67c:1360:8c01::18, 2001:67c:1360:8c01::19, 91.189.91.14, ...
Connecting to archive.ubuntu.com (archive.ubuntu.com)|2001:67c:1360:8c01::18|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 671 [text/html]
Saving to: ‘index.html.2’
100%[========================================================================================================================================================>] 671 --.-K/s in 0s
2014-10-02 10:52:34 (30,8 MB/s) - ‘index.html.2’ saved [671/671]
I can resolve the domain with dig
:
gonvaled@pegasus ~ » dig archive.ubuntu.com
; <<>> DiG 9.9.5-3-Ubuntu <<>> archive.ubuntu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36593
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 7, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;archive.ubuntu.com. IN A
;; ANSWER SECTION:
archive.ubuntu.com. 572 IN A 91.189.92.200
archive.ubuntu.com. 572 IN A 91.189.91.15
archive.ubuntu.com. 572 IN A 91.189.91.14
archive.ubuntu.com. 572 IN A 91.189.91.13
archive.ubuntu.com. 572 IN A 91.189.88.153
archive.ubuntu.com. 572 IN A 91.189.88.149
archive.ubuntu.com. 572 IN A 91.189.92.201
;; Query time: 2 msec
;; SERVER: 10.11.0.1#53(10.11.0.1)
;; WHEN: Thu Oct 02 10:58:00 CEST 2014
;; MSG SIZE rcvd: 148
But I can not ping the site (not because the site is not replying to pings, but because Network is unreachable
):
gonvaled@pegasus ~ » ping archive.ubuntu.com
connect: Network is unreachable
Traceroute is also failing:
gonvaled@pegasus ~ » traceroute archive.ubuntu.com
traceroute to archive.ubuntu.com (91.189.88.149), 30 hops max, 60 byte packets
connect: Network is unreachable
This is my network config (nothing out of the ordinary!):
gonvaled@pegasus ~ » ifconfig eth0
eth0 Link encap:Ethernet HWaddr 2c:76:8a:e0:b0:6b
inet addr:10.11.44.84 Bcast:10.11.255.255 Mask:255.255.0.0
inet6 addr: 2001:4dd0:fff4:11:2c3f:5f86:f975:579f/64 Scope:Global
inet6 addr: fe80::2e76:8aff:fee0:b06b/64 Scope:Link
inet6 addr: 2001:4dd0:fff4:11:2e76:8aff:fee0:b06b/64 Scope:Global
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:37502 errors:0 dropped:0 overruns:0 frame:0
TX packets:14119 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:13558552 (13.5 MB) TX bytes:3533448 (3.5 MB)
gonvaled@pegasus ~ » route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.11.0.0 * 255.255.0.0 U 0 0 0 eth0
link-local * 255.255.0.0 U 1000 0 0 eth0
What else could I check to narrow down this issue?
EDIT
There seem to be two things at play here: IPv6 and default gateway. Whenever I enable wlan, I get these routes:
gonvaled@pegasus ~ » route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 10.11.0.1 0.0.0.0 UG 0 0 0 wlan0
10.11.0.0 * 255.255.0.0 U 0 0 0 eth0
10.11.0.0 * 255.255.0.0 U 9 0 0 wlan0
link-local * 255.255.0.0 U 1000 0 0 eth0
Which has a default gateway, and makes IPv4 work fine.
So now I still have two open questions:
- Why don't I get a default gateway with my eth0? (this is the real issue at hand)
- Why does IPv6 does not need a default gateway? (this is what was confusing me all along)
wget
used IPv6, yourping
IPv4. Maybe your IPv4 networking isn't working at all?2001:67c:1360:8c01::18|:80
which is via IPv6. You can force it to use v4 likewget -4 ...
.wget -4
just fails. I was not seeing the forest because of so many trees :). Thanks. Now I wonder if that is an issue with my interface configuration (I have indeed been playing with it recently) or if it has something to do with the network itself.