diff --git a/library/network/test/port_aliases_test.rb b/library/network/test/port_aliases_test.rb
index 3575f7eb2..4566209a3 100755
--- a/library/network/test/port_aliases_test.rb
+++ b/library/network/test/port_aliases_test.rb
@@ -20,11 +20,180 @@
 CONTENT
 
 describe Yast::PortAliases do
-  describe ".LoadAndReturnNameToPort" do
-    before do
-      allow(::File).to receive(:read).and_return(FILE_CONTENT)
+  before do
+    allow(::File).to receive(:read).and_return(FILE_CONTENT)
+  end
+
+  describe ".IsAllowedPortName" do
+    context "when nil is given" do
+      it "logs an error" do
+        expect(Yast::Builtins).to receive(:y2error).with(/Invalid/, nil)
+
+        subject.IsAllowedPortName(nil)
+      end
+
+      it "returns false" do
+        expect(subject.IsAllowedPortName(nil)).to eq(false)
+      end
     end
 
+    context "when a number is given" do
+      context "within the valid port range" do
+        it "returns true" do
+          expect(subject.IsAllowedPortName("65535")).to eq(true)
+        end
+      end
+
+      context "beyond the upper limit" do
+        it "returns false" do
+          expect(subject.IsAllowedPortName("65536")).to eq(false)
+        end
+      end
+      context "below the lower limit" do
+        # FIXME: regexp avoid having negative numbers, which are going to be considered as port name
+        # instead a port number.
+        xit "returns false" do
+          expect(subject.IsAllowedPortName("-1")).to eq(false)
+        end
+      end
+    end
+
+    context "when a name is given" do
+      context "containing only valid chars" do
+        it "returns true" do
+          expect(subject.IsAllowedPortName("valid-service.name+")).to eq(true)
+        end
+      end
+
+      context "containing not valid chars" do
+        it "returns false" do
+          expect(subject.IsAllowedPortName("Not valid service name")).to eq(false)
+        end
+      end
+    end
+  end
+
+  describe ".AllowedPortNameOrNumber" do
+    it "returns an informing message" do
+      message = subject.AllowedPortNameOrNumber
+
+      expect(message).to include("a-z")
+      expect(message).to include("A-Z")
+      expect(message).to include("0-9")
+      expect(message).to include("*+._-")
+      expect(message).to include("0 to 65535")
+    end
+  end
+
+  describe ".GetListOfServiceAliases" do
+    context "when a port number is given" do
+      before do
+        allow(Yast::SCR).to receive(:Execute)
+          .with(anything, /.*grep.*#{port_number}.*\/etc\/services \|.*sed.*/)
+          .and_return("exit" => 0, "stdout" => command_stdout)
+      end
+
+      context "and there is a service for such port number" do
+        let(:port_number) { "10541" }
+        let(:command_stdout) { "MOS-upper\nMOS-upper" }
+
+        it "returns a list holding both, the port number and its aliases" do
+          expect(subject.GetListOfServiceAliases(port_number)).to eq(["10541", "MOS-upper"])
+        end
+      end
+
+      context "but there is not a service for such port number" do
+        let(:port_number) { "666" }
+        let(:command_stdout) { "" }
+
+        it "returns a list holding only the given port number" do
+          expect(subject.GetListOfServiceAliases(port_number)).to eq([port_number])
+        end
+      end
+    end
+
+    context "when a port name is given" do
+      context "and its an allowed port name" do
+        context "and there is a service for such port name" do
+          let(:port_name) { "MOS-upper" }
+
+          it "returns a list holding both, given name and its port number" do
+            expect(subject.GetListOfServiceAliases(port_name)).to eq(["10541", "MOS-upper"])
+          end
+        end
+
+        context "but there is not a service for such port number" do
+          let(:port_name) { "SomethingWrong" }
+
+          it "returns a list holding only the given name" do
+            expect(subject.GetListOfServiceAliases(port_name)).to eq([port_name])
+          end
+        end
+
+        context "but it is not an allowed port name" do
+          let(:port_name) { "Something Not Allowed" }
+
+          it "logs an error" do
+            expect(Yast::Builtins).to receive(:y2error).with(/not allowed/, port_name)
+
+            subject.GetListOfServiceAliases(port_name)
+          end
+
+          it "returns a list holding only the given name" do
+            expect(subject.GetListOfServiceAliases(port_name)).to eq([port_name])
+          end
+        end
+      end
+    end
+  end
+
+  describe ".IsKnownPortName" do
+    context "when a known port name is given" do
+      let(:port_name) { "blocks" }
+
+      it "returns true" do
+        expect(subject.IsKnownPortName(port_name)).to eq(true)
+      end
+    end
+
+    context "when an unknown port name is given" do
+      let(:port_name) { "unknown-port" }
+
+      it "returns false" do
+        expect(subject.IsKnownPortName(port_name)).to eq(false)
+      end
+    end
+  end
+
+  describe ".GetPortNumber" do
+    context "when a port number is given" do
+      let(:port_number) { "80" }
+
+      it "returns the Integer port number" do
+        expect(subject.GetPortNumber(port_number)).to eq(80)
+      end
+    end
+
+    context "when a port name is given" do
+      context "and the port is known" do
+        let(:port_name) { "MOS-lower" }
+
+        it "returns its port number" do
+          expect(subject.GetPortNumber(port_name)).to eq(10540)
+        end
+      end
+
+      context "but the port is unknown" do
+        let(:port_name) { "Unknown" }
+
+        it "returns nil" do
+          expect(subject.GetPortNumber(port_name)).to be_nil
+        end
+      end
+    end
+  end
+
+  describe ".LoadAndReturnNameToPort" do
     it "returns integer for given port name" do
       expect(Yast::PortAliases.LoadAndReturnNameToPort("blocks")).to eq 10288
     end