diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-foss-2016a.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-foss-2016a.eb
index 72be70a029a6..87716d265ceb 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-foss-2016a.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-foss-2016a.eb
@@ -15,15 +15,19 @@ easyblock = 'ConfigureMake'
 name = 'UDUNITS'
 version = '2.2.20'
 
-homepage = 'http://www.unidata.ucar.edu/software/udunits/'
+homepage = 'https://www.unidata.ucar.edu/software/udunits/'
 description = """UDUNITS supports conversion of unit specifications between formatted and binary forms,
  arithmetic manipulation of units, and conversion of values between compatible scales of measurement."""
 
 toolchain = {'name': 'foss', 'version': '2016a'}
 toolchainopts = {'opt': True, 'pic': True}
 
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
-source_urls = ['ftp://ftp.unidata.ucar.edu/pub/udunits']
+checksums = ['f10a02014bc6a200d50d8719997bb3a6b3d364de688469d2f7d599688dd9d195']
 
 dependencies = [('expat', '2.1.1')]
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-intel-2016b.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-intel-2016b.eb
index 318c851243e0..6a8d0e5f4251 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-intel-2016b.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.20-intel-2016b.eb
@@ -15,15 +15,19 @@ easyblock = 'ConfigureMake'
 name = 'UDUNITS'
 version = '2.2.20'
 
-homepage = 'http://www.unidata.ucar.edu/software/udunits/'
+homepage = 'https://www.unidata.ucar.edu/software/udunits/'
 description = """UDUNITS supports conversion of unit specifications between formatted and binary forms,
  arithmetic manipulation of units, and conversion of values between compatible scales of measurement."""
 
 toolchain = {'name': 'intel', 'version': '2016b'}
 toolchainopts = {'pic': True}
 
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
-source_urls = ['ftp://ftp.unidata.ucar.edu/pub/udunits']
+checksums = ['f10a02014bc6a200d50d8719997bb3a6b3d364de688469d2f7d599688dd9d195']
 
 dependencies = [('expat', '2.2.0')]
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.24-intel-2017a.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.24-intel-2017a.eb
index 97e795ee6139..7a3feda6fe2a 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.24-intel-2017a.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.24-intel-2017a.eb
@@ -22,8 +22,11 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'intel', 'version': '2017a'}
 toolchainopts = {'pic': True}
 
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
-source_urls = ['https://www.unidata.ucar.edu/downloads/udunits']
 checksums = ['20bac512f2656f056385429a0e44902fdf02fc7fe01c14d56f3c724336177f95']
 
 dependencies = [('expat', '2.2.0')]
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-foss-2017b.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-foss-2017b.eb
index 547810ebab5e..9f2aecf5aac9 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-foss-2017b.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-foss-2017b.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'foss', 'version': '2017b'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://www.unidata.ucar.edu/downloads/udunits']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['ad486f8f45cba915ac74a38dd15f96a661a1803287373639c17e5a9b59bfd540']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-intel-2017b.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-intel-2017b.eb
index 23d112a91d72..3fbcef4bf6d2 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-intel-2017b.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.25-intel-2017b.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'intel', 'version': '2017b'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://www.unidata.ucar.edu/downloads/udunits']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['ad486f8f45cba915ac74a38dd15f96a661a1803287373639c17e5a9b59bfd540']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-10.2.0.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-10.2.0.eb
index f97a364b2247..006876aac26e 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-10.2.0.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-10.2.0.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'GCCcore', 'version': '10.2.0'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.2.0.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.2.0.eb
index 52196d1fce4e..4a140736c87c 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.2.0.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.2.0.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'GCCcore', 'version': '8.2.0'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.3.0.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.3.0.eb
index bb4c368b1602..040e064b3a3a 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.3.0.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-8.3.0.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'GCCcore', 'version': '8.3.0'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-9.3.0.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-9.3.0.eb
index e7262379da30..3465dd9e1e06 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-9.3.0.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-GCCcore-9.3.0.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'GCCcore', 'version': '9.3.0'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018a.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018a.eb
index 89a0352af572..cac5a4fcbdd0 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018a.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018a.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'foss', 'version': '2018a'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018b.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018b.eb
index 6be5071c12af..232fe067d6b6 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018b.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2018b.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'foss', 'version': '2018b'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2020a.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2020a.eb
index af707cd911d5..fb2526eefcdc 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2020a.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-foss-2020a.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'foss', 'version': '2020a'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2017b.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2017b.eb
index f99517abceae..31b0be1eccc8 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2017b.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2017b.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'intel', 'version': '2017b'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018a.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018a.eb
index 508d08548bcd..803eb09c11d9 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018a.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018a.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'intel', 'version': '2018a'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018b.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018b.eb
index 343867d3cd7e..8078881c2718 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018b.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-intel-2018b.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'intel', 'version': '2018b'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']
 
diff --git a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-iomkl-2018b.eb b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-iomkl-2018b.eb
index 0671da96e6fa..0579d6a1fbfa 100644
--- a/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-iomkl-2018b.eb
+++ b/easybuild/easyconfigs/u/UDUNITS/UDUNITS-2.2.26-iomkl-2018b.eb
@@ -22,7 +22,10 @@ description = """UDUNITS supports conversion of unit specifications between form
 toolchain = {'name': 'iomkl', 'version': '2018b'}
 toolchainopts = {'pic': True}
 
-source_urls = ['https://fossies.org/linux/privat/legacy/']
+source_urls = [
+    'https://artifacts.unidata.ucar.edu/repository/downloads-udunits/',
+    'http://sources.easybuild.io/u/UDUNITS/',
+]
 sources = [SOURCELOWER_TAR_GZ]
 checksums = ['368f4869c9c7d50d2920fa8c58654124e9ed0d8d2a8c714a9d7fdadc08c7356d']