Ubuntu
systemd package

systemd-resolved can't resolve Comcast mail server addresses

Bug #1805027 reported by Tomdkat
52
This bug affects 11 people
Affects Status Importance Assigned to Milestone
systemd (Ubuntu)
Triaged
Undecided
Unassigned

Bug Description

1) Ubuntu release: 18.10
2) systemd-resolved version: (Default latest version that comes with Ubuntu 18.10)
3) Expected behavior: Comcast's POP3 mail server addresses to be resolved to IP addresses
4) Actual behavior: Comcast's POP3 mail server addresses can't be resolved to IP addresses

Starting on Monday, November 19, 2018, Comcast made a DNS change related to its POP3 mail servers (mail.comcast.net and pop3.comcast.net) that prevent resolved from being able to resolve those domains into IP addresses. When I try to ping either host (mail.comcast.net or pop2.comcast.net), I get this error:

tom@deathstar:~$ ping mail.comcast.net
ping: mail.comcast.net: Name or service not known
tom@deathstar:~$

When I manually lookup up the domain, I get these results:

tom@deathstar:~$ nslookup mail.comcast.net
Server: 127.0.0.53
Address: 127.0.0.53#53

Non-authoritative answer:
mail.comcast.net canonical name = imap.ge.xfinity.com.
Name: imap.ge.xfinity.com
Address: 96.118.242.209
Name: imap.ge.xfinity.com
Address: 96.118.242.197
Name: imap.ge.xfinity.com
Address: 96.118.242.233
Name: imap.ge.xfinity.com
Address: 96.118.242.225
Name: imap.ge.xfinity.com
Address: 96.118.242.226
Name: imap.ge.xfinity.com
Address: 96.118.242.217
Name: imap.ge.xfinity.com
Address: 96.118.242.208
Name: imap.ge.xfinity.com
Address: 96.118.242.230
Name: imap.ge.xfinity.com
Address: 96.118.242.232
Name: imap.ge.xfinity.com
Address: 96.118.242.218
Name: imap.ge.xfinity.com
Address: 96.118.242.211
Name: imap.ge.xfinity.com
Address: 96.118.242.242
Name: imap.ge.xfinity.com
Address: 96.118.242.221
Name: imap.ge.xfinity.com
Address: 96.118.242.196
Name: imap.ge.xfinity.com
Address: 96.118.208.40
Name: imap.ge.xfinity.com
Address: 96.118.208.99
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:9:f816:3eff:fee8:4f07
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:9:f816:3eff:fe7d:1b0c
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:9:f816:3eff:fe25:5ae5
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:9:f816:3eff:fef6:babc
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:9:f816:3eff:fe87:c172
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:9:f816:3eff:fee6:7a57
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:9:f816:3eff:fe0f:a4a
Name: imap.ge.xfinity.com
Address: 2001:558:fc11:2:f816:3eff:fec7:cb93
Name: imap.ge.xfinity.com
Address: 2001:558:fee2:1000:f816:3eff:fe42:4f14
Name: imap.ge.xfinity.com
Address: 2001:558:fc18:0:f816:3eff:fe33:9aaa
Name: imap.ge.xfinity.com
Address: 2001:558:fc18:0:f816:3eff:feb2:8c0d
Name: imap.ge.xfinity.com
Address: 2001:558:fc18:0:f816:3eff:fef1:25a5
Name: imap.ge.xfinity.com
Address: 2001:558:fc18:0:f816:3eff:febd:320a
Name: imap.ge.xfinity.com
Address: 2001:558:fc18:0:f816:3eff:fe36:aba3
Name: imap.ge.xfinity.com
Address: 2001:558:fc18:0:f816:3eff:fe3f:76f2
Name: imap.ge.xfinity.com
Address: 2001:558:fc18:0:f816:3eff:fe45:1d1e

tom@deathstar:~$ dig mail.comcast.net

; <<>> DiG 9.11.4-3ubuntu5-Ubuntu <<>> mail.comcast.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 15037
;; flags: qr rd ra; QUERY: 1, ANSWER: 17, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;mail.comcast.net. IN A

;; ANSWER SECTION:
mail.comcast.net. 15 IN CNAME imap.ge.xfinity.com.
imap.ge.xfinity.com. 12 IN A 96.117.3.119
imap.ge.xfinity.com. 12 IN A 96.117.3.96
imap.ge.xfinity.com. 12 IN A 96.117.3.143
imap.ge.xfinity.com. 12 IN A 96.117.3.145
imap.ge.xfinity.com. 12 IN A 96.117.3.129
imap.ge.xfinity.com. 12 IN A 96.117.3.148
imap.ge.xfinity.com. 12 IN A 96.117.3.201
imap.ge.xfinity.com. 12 IN A 96.117.3.136
imap.ge.xfinity.com. 12 IN A 96.118.133.238
imap.ge.xfinity.com. 12 IN A 96.117.3.128
imap.ge.xfinity.com. 12 IN A 96.117.3.144
imap.ge.xfinity.com. 12 IN A 96.117.2.238
imap.ge.xfinity.com. 12 IN A 96.117.3.110
imap.ge.xfinity.com. 12 IN A 96.117.3.140
imap.ge.xfinity.com. 12 IN A 96.117.3.154
imap.ge.xfinity.com. 12 IN A 96.117.3.132

;; Query time: 13 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Tue Nov 20 06:58:31 PST 2018
;; MSG SIZE rcvd: 334

tom@deathstar:~$

Before November 19, 2018, everything was working fine. The initial indication there was a problem was Mozilla Thunderbird failed to connect to Comcast's POP3 mail server. Once I did some investigation, I found the information above.

I have since disabled system-resolved and have installed "Unbound". After installing "Unbound", I'm able to ping "mail.comcast.net" without issue and Mozilla Thunderbird can contact successfully Comcast's POP3 mail servers.

I started a thread about this on Ubuntuforums.org:

https://ubuntuforums.org/showthread.php?t=2406399

and others report being impacted by this as well.

Let me know if more information is needed! Thanks!

Revision history for this message
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in systemd (Ubuntu):
status: New → Confirmed
Revision history for this message
Trev Peterson (trev-advanced-reality) wrote :

This certainly seems like an ubuntu 18.04 bug. 3 machines here all affected. dig imap.comcast.net resolves to imap.ge.xfinity.com. Ping, telnet, wget are all unable to resolve imap.comcast.net.

Revision history for this message
Brian Murray (brian-murray) wrote :

fetchmail is also affected e.g.

 $ fetchmail -p imap imap.comcast.net
Enter password for <email address hidden>:
fetchmail: couldn't find canonical DNS name of imap.comcast.net (imap.comcast.net): Temporary failure in name resolution
fetchmail: Query status=11 (DNS)

Even if you aren't using comcast for email this is a good way to test it, just use some made up password.

tags: added: rls-dd-incoming
Revision history for this message
Brian Murray (brian-murray) wrote :

There is a systemd SRU for Cosmic in progress, bug 1804487, which may be the same issue as this bug. If someone affected could install the version of systemd from cosmic-proposed and report back that would be helpful. Thanks!

Revision history for this message
Mathieu Trudel-Lapierre (cyphermox) wrote :

Setting to Triaged: it's easily reproduced by developers, and we have all the information we need to debug it -- nothing is secret or hidden, just needs someone to look at the packets and what resolved does with them.

Changed in systemd (Ubuntu):
status: Confirmed → Triaged
Francis Ginther (fginther)
tags: added: id-5c094e11580a2f05d67fe6f3
Revision history for this message
Brian Murray (brian-murray) wrote :

I copied the patch debian/patches/resolved-Increase-size-of-TCP-stub-replies.patch (cherry picked from commit e6eed9445956cfa496e1db933bfd3530db23bfce) from the upload of systemd that was in cosmic-proposed and added to a package I built for 18.04 on top of systemd version 237-3ubuntu10.11. I installed the following packages:

ii libnss-systemd:amd64 237-3ubuntu10.11~ppa1 amd64 nss module providing dynamic user and group name resolution
ii libpam-systemd:amd64 237-3ubuntu10.11~ppa1 amd64 system and service manager - PAM module
ii libsystemd0:amd64 237-3ubuntu10.11~ppa1 amd64 systemd utility library
ii systemd 237-3ubuntu10.11~ppa1 amd64 system and service manager
ii systemd-sysv 237-3ubuntu10.11~ppa1 amd64 system and service manager - SysV links

and the issue was not resolved.

 $ wget imap.comcast.net
--2019-01-17 09:15:18-- http://imap.comcast.net/
Resolving imap.comcast.net (imap.comcast.net)... failed: Name or service not known.
wget: unable to resolve host address ‘imap.comcast.net’

Revision history for this message
Brian Murray (brian-murray) wrote :

The workaround, of adding "options edns0" to my /etc/resolv.conf, in bug 1811471 resolved the issue for me. That's only temporary though as /etc/resolv.conf will get overwritten.

Revision history for this message
Brian Murray (brian-murray) wrote :

I installed the version of systemd from -updates for Ubuntu 18.04 and Ubuntu 18.10, with those versions of systemd I was no longer able to recreate the problem regarding resolving imap.comcast.net. As such I am marking this bug as a duplicate of bug 1811471.

Revision history for this message
Markus Alexander Kuppe (c-launchpad-net-lemmster-de) wrote :

The same symptons appear for "emea.mail.microsoft.com" even with systemd 237-3ubuntu10.21 from -updates.

To post a comment you must log in.
This report contains Public information  
Everyone can see this information.
Subscribing...

Other bug subscribers

Remote bug watches

Bug watches keep track of this bug in other bug trackers.