Why are Nix programs not able to resolve mDNS names when native programs are?

Leonora Tindall

21:42, 25/08/2023

My native programs (on Fedora) are able to resolve mDNS / Avahi / zeroconf names, like so:

$ ping felonyspork.local -c 1  
PING felonyspork.local (192.168.88.169) 56(84) bytes of data.
64 bytes from 192.168.88.169 (192.168.88.169): icmp_seq=1 ttl=64 time=1.73 ms

--- felonyspork.local ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 1.734/1.734/1.734/0.000 ms

$ ssh felonyspork.local        
Last login: Mon Apr 25 16:05:34 2022 from 192.168.88.200

$ exit
Connection to felonyspork.local closed.

However, my Nix-installed programs are not:

$ nix-shell -p openssh ssh-tools

[nix-shell:~/src/nixconfig]$ ssh-ping -c 1 felonyspork.local
SSHPING felonyspork.local

--- felonyspork.local ping statistics ---
1 requests transmitted, 0 requests received, 100% request loss

[nix-shell:~/src/nixconfig]$ ssh felonyspork.local
ssh: Could not resolve hostname felonyspork.local: Name or service not known

I have mDNS configured in /etc/nsswitch.conf:

hosts:      files myhostname mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns

And avahi-daemon is running on my system.

How can I get Nix programs to correctly resolve mDNS names? This is especially important, because deploying with Morph requires a working Nix SSH session.

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Leonora Tindall

21:42, 25/08/2023

Liên kết còn thiếu ở đây là nscd; chỉ cần cài đặt nscd và khởi động trình nền làm cho các chương trình do Nix cài đặt hoạt động.

$ sudo dnf cài đặt nscd
$ Sudo systemctl bắt đầu nscd.service
$ nix-shell -p ssh-công cụ

[nix-shell:~]$ ssh-ping felonyspork.local
SSHPING felonyspork.local
Pong từ felonyspork.local: ssh_seq=1 time=2191 ms
Pong từ felonyspork.local: ssh_seq=2 time=1310 ms
^C
--- felonyspork.local ping thống kê ---
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