Can't connect to anything with University internet via ethernet

unistudentneedhelp · 2016-08-20 21:30:14

Hello, everyone. I'm having a problem with connecting to my university's internet via ethernet.

I had to register my device with it's MAC address and it assigned an IP address to me (10.41.72.65). However, when I use dhcpcd to set up my connection, I can't ping/connect to any sites or IP addresses besides internal ones as it just drops all the packets.

Here's the output dhcpcd.

DUID 00:01:00:01:1f:42:b2:b4:28:c2:dd:57:3f:e1
enp2s0: IAID 3f:bc:26:af
enp2s0: rebinding lease of 10.41.79.0
enp2s0: probing address 10.41.79.0/21
enp2s0: soliciting an IPv6 router
enp2s0: leased 10.41.79.0 for 28800 seconds
enp2s0: adding route to 10.41.72.0/21
enp2s0: adding default route via 10.41.72.1
forked to background, child pid 462

I have no idea how to fix this, as I thing it's assigning me the wrong IP address. Any help would be appreciated.

Awebb · 2016-08-20 22:39:59

This is most likely not a problem with your setup in a sense, that you have done anything inherently wrong. This is a sure case to bring up with your network admin, help desk or whatever minions your institute shelters. However, if you provided the output of "ip link" and "ip addr" and the actual output of a ping going wrong, we could engage in idle speculations.

pypi · 2016-08-20 23:55:37

I'd imagine that you will need some kind of "internet enabler". I'm not sure how standardized these things are, but here's what my institution uses (this is my modified version, but something similar...):

#!/usr/bin/python2

import os, sys, telnetlib, getpass

def enable(username, password, info='enable'):
    if info == "enable":
        choice = "1"
        statustext = "Internet connection established"
    else:
        choice = "2"
        statustext = "Internet connection deactivated"
        
    tn = telnetlib.Telnet("ienabler.canterbury.ac.nz",  259)
    tn.read_until(b"User: ")
    tn.write(username + b"\n")
    tn.read_until(b"password: ")
    tn.write(password + b"\n")
    response = tn.expect(["choice", "denied"],  5)
    if response[0] == 0:
        tn.write(choice)
        print(statustext)
    else:
        print("Bad username or password provided.")
    del tn, username, password,  choice,  response,  statustext
    
if __name__=="__main__":
    enable(getpass.getuser().encode('ascii'), getpass.getpass().encode('ascii'))

I could also be completely wrong!

ewaller · 2016-08-21 00:12:50

unistudentneedhelp wrote:

I had to register my device with it's MAC address and it assigned an IP address to me (10.41.72.65).

What is "it" ?

However, when I use dhcpcd to set up my connection, I can't ping/connect to any sites or IP addresses besides internal ones as it just drops all the packets.
Here's the output dhcpcd.
...
enp2s0: rebinding lease of 10.41.79.0
enp2s0: probing address 10.41.79.0/21
...
enp2s0: leased 10.41.79.0 for 28800 seconds
enp2s0: adding route to 10.41.72.0/21
enp2s0: adding default route via 10.41.72.1
f...
I have no idea how to fix this, as I thing it's assigning me the wrong IP address. Any help would be appreciated.

I agree that DHCP is not assigning you 10.41.72.65. You are being assigned 10.41.72.0/21. You say you can ping other internal addresses; can you use any higher level protocols on any of those devices? HTTP? SSH?
Can you ping 10.41.72.1?

It might be that your address is being blocked at the bridge because you are not on an assigned address. Could it be that dynamic addresses are not provided internet access, but only LAN access? Maybe you are supposed to be using a static address?

unistudentneedhelp · 2016-08-21 03:46:32

@ewaller

"It" is my university's web-based registration system where I go to register devices for use on the network. Sorry for not clarifying that earlier.

As for higher level protocols, I can use HTTP to connect to my university's registration system. I can ping 10.41.72.1. I can't connect to sites such as Google or the Arch Linux forums. By static address do you mean that I am supposed to specify my IP address at 10.41.72.65?

Last edited by unistudentneedhelp (2016-08-21 03:49:15)

Awebb · 2016-08-21 09:21:04

Give us that "ip link" and "ip addr" already.

ewaller · 2016-08-21 14:11:10

unistudentneedhelp wrote:

By static address do you mean that I am supposed to specify my IP address at 10.41.72.65?

Yes. It is worth a try. But, Awebb's request would be helpful

unistudentneedhelp · 2016-08-21 18:55:27

ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 3f:22:3b:1c:26:af brd ff:ff:ff:ff:ff:ff
    inet 10.41.79.1/21 brd 10.41.79.255 scope global enp2s0
       valid_lft forever preferred_lft forever
    inet6 fe80::3822:3fff:febc:26af/64 scope link 
       valid_lft forever preferred_lft forever
3: wlp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 28:c2:dd:57:3f:e1 brd ff:ff:ff:ff:ff:ff

ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 3f:22:3b:1c:26:af brd ff:ff:ff:ff:ff:ff
3: wlp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 28:c2:dd:57:3f:e1 brd ff:ff:ff:ff:ff:ff

ewaller · 2016-08-21 19:21:00

That looks really wrong. You have an address 10.41.79.1, but that is also your default route. The dhcpcd output has you at 10.41.79.0, which is really wrong.

Okay, let's try a quick and nasty experiment
Try the following two commands:
sudo ip addr add 10.41.72.65/21 dev eno1
sudo ip addr del 10.41.79.1 dev eno1

And let's see what happens. Note these are transient changes and are just an experiment.

unistudentneedhelp · 2016-08-21 20:58:58

The first command executed properly, and the second one gave me the following error.

Warning: Executing wildcard deletion to stay compatible with old scripts.
         Explicitly specify the prefix length (10.41.79.1/32) to avoid this warning.
         This special behaviour is likely to disappear in further releases,
         fix your scripts!
RTNETLINK answers: Cannot assign requested address

Here's the new ip addr and ip link output, if it helps.

ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 3f:22:3b:1c:26:af brd ff:ff:ff:ff:ff:ff
    inet 10.41.79.0/21 brd 10.41.79.255 scope global enp2s0
       valid_lft forever preferred_lft forever
    inet 10.41.72.65/21 scope global secondary enp2s0
       valid_lft forever preferred_lft forever
    inet6 fe80::3822:3fff:febc:26af/64 scope link 
       valid_lft forever preferred_lft forever
3: wlp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 28:c2:dd:57:3f:e1 brd ff:ff:ff:ff:ff:ff

ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 3f:22:3b:1c:26:af brd ff:ff:ff:ff:ff:ff
3: wlp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 28:c2:dd:57:3f:e1 brd ff:ff:ff:ff:ff:ff

ewaller · 2016-08-21 22:43:24

Drat, I got the address wrong. Try
sudo ip addr del 10.41.79.0 dev eno1
You will still get the Warning.

The goal here is to get rid off all addresses but the one you were assigned by the web-registration system.

unistudentneedhelp · 2016-08-22 02:13:29

Both commands ran successfully, however I still have no connection and can no longer connect to anything on the LAN.

Here's the new ip addr and ip link outputs.

ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 3f:22:3b:1c:26:af brd ff:ff:ff:ff:ff:ff
    inet 10.41.72.65/21 scope global enp2s0
       valid_lft forever preferred_lft forever
    inet6 fe80::3822:3fff:febc:26af/64 scope link 
       valid_lft forever preferred_lft forever
3: wlp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 28:c2:dd:57:3f:e1 brd ff:ff:ff:ff:ff:ff

ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 3f:22:3b:1c:26:af brd ff:ff:ff:ff:ff:ff
3: wlp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 28:c2:dd:57:3f:e1 brd ff:ff:ff:ff:ff:ff

Awebb · 2016-08-22 09:28:55

ewaller: Are you sure that was a good idea? If my math isn't failing me, a .0 address is valid in a 21 bit subnet. As we know little to nothing about their internal mechanisms and as we already know, that unistudentneedhelp can indeed connect to addresses inside the local network segment, I recommend, again (and again, if necessary, as often as it takes) to send a message to the helpdesk (or whatever the IT support is called there). In my experience, the most common reason for such problems, is the simple fact that you have not been cleared for WAN traffic. I'd also take pypi's advice into account, but I wouldn't just use a random script. Try some full bloated blown connection tool like Networkmanager with a GUI, those things often recognize authentication requirements.

ewaller · 2016-08-22 15:12:51

Awebb wrote:

ewaller: Are you sure that was a good idea? If my math isn't failing me, a .0 address is valid in a 21 bit subnet.

Good idea? Don't know. At issue is that address is (was) assigned to the wired nic:

 inet 10.41.79.0/21 brd 10.41.79.255 scope global enp2s0

. Bad idea? trying it won't hurt anything -- I am not baking it into a configuring; just fscking with the current state. Nothing that a reboot won't fix.

As we know little to nothing about their internal mechanisms and as we already know, that unistudentneedhelp can indeed connect to addresses inside the local network segment, I recommend, again (and again, if necessary, as often as it takes) to send a message to the helpdesk (or whatever the IT support is called there). In my experience, the most common reason for such problems, is the simple fact that you have not been cleared for WAN traffic.

Absolutely, on all counts. I have a hunch that the address he was assigned by the web interface may have been cleared -- that is what I was really trying to probe. I have seen some highly enlightened universities that make no assumptions as to what OS you are using. I have also seen institutions with severe rectocranial inversions that demand you use Windows.

unistudentneedhelp, Have you the option of trying Windows on your machine to connect to the network? Does it work? Tangentially, have you previously used Windows on that network, perhaps the DHCP server now sees this as a different machine. Again, this may be an argument for talking to the help desk.

Last edited by ewaller (2016-08-22 15:13:26)

paulkerry · 2016-08-22 20:14:12

You could try using a linux boot disk (usb or cd) to check that the network connection is working as expected.
If it doesn't work, then there is a problem with your MAC registration, whereas if it does work, there is something wrong with your arch installation...

Arch Linux

#1 2016-08-20 21:30:14

Can't connect to anything with University internet via ethernet

#2 2016-08-20 22:39:59

Re: Can't connect to anything with University internet via ethernet

#3 2016-08-20 23:55:37

Re: Can't connect to anything with University internet via ethernet

#4 2016-08-21 00:12:50

Re: Can't connect to anything with University internet via ethernet

#5 2016-08-21 03:46:32

Re: Can't connect to anything with University internet via ethernet

#6 2016-08-21 09:21:04

Re: Can't connect to anything with University internet via ethernet

#7 2016-08-21 14:11:10

Re: Can't connect to anything with University internet via ethernet

#8 2016-08-21 18:55:27

Re: Can't connect to anything with University internet via ethernet

#9 2016-08-21 19:21:00

Re: Can't connect to anything with University internet via ethernet

#10 2016-08-21 20:58:58

Re: Can't connect to anything with University internet via ethernet

#11 2016-08-21 22:43:24

Re: Can't connect to anything with University internet via ethernet

#12 2016-08-22 02:13:29

Re: Can't connect to anything with University internet via ethernet

#13 2016-08-22 09:28:55

Re: Can't connect to anything with University internet via ethernet

#14 2016-08-22 15:12:51

Re: Can't connect to anything with University internet via ethernet

#15 2016-08-22 20:14:12

Re: Can't connect to anything with University internet via ethernet

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