Error when trying to install Firebase with pod relative to nanopb

I'm trying to install Firebase in my swift application with Cocoapod like this :

pod 'Firebase/Core'
pod 'Firebase/Messaging'

But got an error when i'm processing the pod install :

[!] Error installing nanopb
[!] /usr/bin/curl -f -L -o /var/folders/82/qk0yjdtx5xl0hnzsk2s2h30h0000gn/T/d20170722-19429-tm6t4q/file.tgz http://koti.kapsi.fi/~jpa/nanopb/download/nanopb-0.3.8.tar.gz --create-dirs --netrc-optional

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   330  100   330    0     0   1941      0 --:--:-- --:--:-- --:--:--  1952
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
curl: (22) The requested URL returned error: 503 Service Unavailable

Just the server down ? or am I missing something Is there an other way to do without nanopb ?