Comment 6 for bug 232051

I run into this problem when running in.talkd daemons between Debian 8.5 and Fedora 24. I'm letting everyone know about how I could make the two work even though not one of the involved machined was an Ubuntu one, because I guess the issue other people experienced years ago could be caused by the same configuration errors.

Involved distros (lsb_release -d):
Description: Debian GNU/Linux 8.5 (jessie)
Description: Fedora release 24 (Twenty Four)

Involved packages:
(dpkg-query --search /usr/sbin/in.ntalkd)
talkd: /usr/sbin/in.ntalkd
(dpkg-query --show talkd)
talkd 0.17-15

(rpm -qf /usr/sbin/in.ntalkd)
talk-server-0.17-50.fc24.x86_64

First thing, I put the following lines in the /etc/xinetd.d/ntalk file on both machines:

service ntalk
{
        disable = no
        id = talk-dgram
        socket_type = dgram
        protocol = udp
        flags = IPv4
        #user = nobody
        user = talk
        server = /usr/sbin/in.ntalkd
        wait = yes
}

As I did not want the nobody user to be part of a system group (it's supposed to be always the least-capable user in the system), I created on both machines an ad-hoc talk user with the command:

[root@... ~]# useradd -c 'in.talkd User' -d /nonexistent -s /usr/sbin/nologin -r -g tty talk

Line "flags = IPv4" was necessary in order to prevent the two talk client to hang after displaying: [No connection yet] followed by: [Checking for invitation on caller's machine] and the following line appearing in the Fedora machine log /var/log/messages:

Jul 14 12:23:57 wrkstn07 talkd[2457]: recvfrom: bogus address length

Restricting the two talkd daemons made this error disappear. However, another error showed up that would prevent the talk session to initiate:

On the Debian machine: [Target machine does not recognize us] ... [Trying to connect to your party's talk daemon]
On the Fedora machine: [Waiting for your party to respond] ... [Trying to connect to your party's talk daemon]

On the Fedora machine I got this line in the log:

Jul 14 12:31:10 wrkstn07 talkd[2467]: 192.168.1.63: bad dns

I then added this line on the Fedora machine's /etc/hosts file:

192.168.1.63 debian

The last attempt at talking between the two machines worked:

[Connection established]

Hope others will benefit from this followup.