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eDio

Member

From: Ukraine, Kyiv

Registered: 2008-12-02

Posts: 422

/etc/resolv.conf between netctl profile switches

Hi, all.

I use same laptop at home and in my office. Network is managed by netct. At home I connect using a profile generated by wifi-menu, in the office — plain ethernet-dhcp profile form examples folder.
With both connections nameservers are obtained via dhcp.

The issue is that after switching from office ethernet-dhcp to my home wi-fi netctl profile, /etc/resolve.conf retains nameserver and domain entries from the office connection. My home's nameserver entry gets appended to the end of the resolv.conf file. This, of course, causes unacceptable delays when resolving domain names, so I have to edit /etc/resolve.conf manually every time I've been using that office's connection.

I'm wondering whether there is something wrong with my setup.

Profiles are nothing special, as I said:

Description='Automatically generated profile by wifi-menu'
Interface=wlp3s0
Connection=wireless
Security=wpa
ESSID=my_ssid
IP=dhcp
Key=my_passwd

Description='A dhcp ethernet connection'
Interface=enp0s25
Connection=ethernet
IP=dhcp
DHCPClient='dhcpcd'

Please, help me to resolve that issue. Feel free to ask for more details if needed.

Thanks in advance for help.

Last edited by eDio (2014-04-12 19:30:51)

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WonderWoofy

Member

From: Los Gatos, CA

Registered: 2012-05-19

Posts: 8,414

Re: /etc/resolv.conf between netctl profile switches

Can check out what the nameserver IPs are for the two networks and specify them manually to see what happens?  I'm curious if it will still append if it is set up that way.

Otherwise, as a workaround, you could just use the same nameservers for both networks.  For instance, 8.8.8.8 or OpenDNS (whatever their IPs are).  In any case, if this is consistent among all network changes it is probably a bug and should be reported as such.  I don't use netctl anymore, so I cannot really comment any further.

eDio

Member

From: Ukraine, Kyiv

Registered: 2008-12-02

Posts: 422

Re: /etc/resolv.conf between netctl profile switches

Thanks for the hint. Will try to specify nameservers manually in netctl profiles (can check if that works on Monday).

As for the OpenDNS — not a solution for me, those nameservers resolve intranet specific DNS names.

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branch

Member

Registered: 2014-03-16

Posts: 209

Re: /etc/resolv.conf between netctl profile switches

How exactly are you switching profiles? Since these profiles are on different interfaces, nothing prevents them from being logically active at the same time even if only one connection is not physically present. Unless you explicitly stop the wired profile, the information from it's dhcp lease (like the name server) will persist until the lease expires.

Check the output from the following commands (the last four need sudo):
netctl status ethernet-dhcp
netctl status ${your_wireless_profile}
cat /run/resolvconf/interfaces/wlp3s0
cat /run/resolvconf/interfaces/enp0s25
dhcpcd --dumplease wlp3s0
dhcpcd --dumplease enp0s25

eDio

Member

From: Ukraine, Kyiv

Registered: 2008-12-02

Posts: 422

Re: /etc/resolv.conf between netctl profile switches

2branch,

I switch them with netctl switch-to command, which is incorrect, as I understand now.
Important notice is that I unplug ethernet cord first, and then I perform a switch.

Also I tried disabling ethernet-dhcp explicitly after switching to wlp3s0 — not helped.

I checked /run/resolvconf/interfaces, and found that enp0s25 is missing. Instead, I have tun0, which contains problematic entries.

dhcpcd --dumplease enp0s25

broadcast_address=10.1.20.255
dhcp_lease_time=604800
dhcp_message_type=5
dhcp_rebinding_time=529200
dhcp_renewal_time=302400
dhcp_server_identifier=10.1.10.2
domain_name=my.company.domain.name
domain_name_servers='10.1.10.2 10.1.1.6'
ip_address=10.1.20.30
network_number=10.1.20.0
ntp_servers=10.1.10.2
routers=10.1.20.1
subnet_cidr=24
subnet_mask=255.255.255.0

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nomorewindows

Member

Registered: 2010-04-03

Posts: 3,424

Re: /etc/resolv.conf between netctl profile switches

I have wired and wireless interfaces going at the same time and it works fine.  Today I was noticing on another machine receiving its' address from DHCP, that it kept its address but was dropping the nameserver entries.

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I may have to CONSOLE you about your usage of ridiculously easy graphical interfaces...
Look ma, no mouse.