diff --git a/server/handlers/wireguard/analyzer/analyzer.go b/server/handlers/wireguard/analyzer/analyzer.go
new file mode 100644
index 0000000..fad1cf4
--- /dev/null
+++ b/server/handlers/wireguard/analyzer/analyzer.go
@@ -0,0 +1,45 @@
+package analyzer
+
+import (
+	"config-lsp/common"
+	"config-lsp/handlers/wireguard"
+	"config-lsp/handlers/wireguard/indexes"
+
+	protocol "github.com/tliron/glsp/protocol_3_16"
+)
+
+type analyzerContext struct {
+	document    *wireguard.WGDocument
+	diagnostics []protocol.Diagnostic
+}
+
+func Analyze(
+	d *wireguard.WGDocument,
+) []protocol.Diagnostic {
+	ctx := &analyzerContext{
+		document:    d,
+		diagnostics: make([]protocol.Diagnostic, 0),
+	}
+
+	analyzeStructureIsValid(ctx)
+
+	if len(ctx.diagnostics) > 0 {
+		return ctx.diagnostics
+	}
+
+	i, indexErrors := indexes.CreateIndexes(d.Config)
+
+	if len(indexErrors) > 0 {
+		return common.ErrsToDiagnostics(indexErrors)
+	}
+
+	d.Indexes = i
+
+	analyzeInterfaceSection(ctx)
+	analyzeDNSPropertyContainsFallback(ctx)
+	analyzeKeepAlivePropertyIsSet(ctx)
+	analyzeSymmetricPropertiesSet(ctx)
+	analyzeDuplicateAllowedIPs(ctx)
+
+	return ctx.diagnostics
+}
diff --git a/server/handlers/wireguard/analyzer/analyzer_test.go b/server/handlers/wireguard/analyzer/analyzer_test.go
new file mode 100644
index 0000000..50ac57c
--- /dev/null
+++ b/server/handlers/wireguard/analyzer/analyzer_test.go
@@ -0,0 +1,57 @@
+package analyzer
+
+import (
+	"config-lsp/handlers/wireguard/parser"
+	"config-lsp/utils"
+	"testing"
+)
+
+func TestMultipleIntefaces(t *testing.T) {
+	content := utils.Dedent(`
+[Interface]
+PrivateKey = abc
+
+[Interface]
+PrivateKey = def
+`)
+	p := parser.CreateWireguardParser()
+	p.ParseFromString(content)
+
+	diagnostics := Analyze(p)
+
+	if len(diagnostics) == 0 {
+		t.Errorf("Expected diagnostic errors, got %d", len(diagnostics))
+	}
+}
+
+func TestInvalidValue(t *testing.T) {
+	content := utils.Dedent(`
+[Interface]
+DNS = nope
+`)
+	p := parser.CreateWireguardParser()
+	p.ParseFromString(content)
+
+	diagnostics := Analyze(p)
+
+	if len(diagnostics) == 0 {
+		t.Errorf("Expected diagnostic errors, got %d", len(diagnostics))
+	}
+}
+
+func TestDuplicateProperties(t *testing.T) {
+	content := utils.Dedent(`
+[Interface]
+PrivateKey = abc
+DNS = 1.1.1.1
+PrivateKey = def
+`)
+	p := parser.CreateWireguardParser()
+	p.ParseFromString(content)
+
+	diagnostics := Analyze(p)
+
+	if len(diagnostics) == 0 {
+		t.Errorf("Expected diagnostic errors, got %d", len(diagnostics))
+	}
+}
diff --git a/server/handlers/wireguard/analyzer/property.go b/server/handlers/wireguard/analyzer/property.go
new file mode 100644
index 0000000..2a80141
--- /dev/null
+++ b/server/handlers/wireguard/analyzer/property.go
@@ -0,0 +1,136 @@
+package analyzer
+
+import (
+	"config-lsp/common"
+	"config-lsp/utils"
+	"context"
+	"fmt"
+	"net/netip"
+	"strings"
+
+	protocol "github.com/tliron/glsp/protocol_3_16"
+)
+
+func analyzeDNSPropertyContainsFallback(
+	ctx *analyzerContext,
+) {
+	sections, found := ctx.document.Indexes.SectionsByName["Interface"]
+
+	if !found {
+		return
+	}
+
+	interfaceSection := sections[0]
+
+	property := interfaceSection.FindFirstPropertyByName("DNS")
+
+	if property == nil {
+		return
+	}
+
+	dnsAmount := len(strings.Split(property.Value.Value, ","))
+
+	if dnsAmount == 1 {
+		ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+			Message:  "There is only one DNS server specified. It is recommended to set up fallback DNS servers",
+			Severity: &common.SeverityHint,
+			Range:    property.Value.ToLSPRange(),
+		})
+	}
+}
+
+func analyzeKeepAlivePropertyIsSet(
+	ctx *analyzerContext,
+) {
+	for _, section := range ctx.document.Indexes.SectionsByName["Peer"] {
+		// If an endpoint is set, then we should only check for the keepalive property
+		if section.FindFirstPropertyByName("Endpoint") != nil && section.FindFirstPropertyByName("PersistentKeepalive") == nil {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  "PersistentKeepalive is not set. It is recommended to set this property, as it helps to maintain the connection when users are behind NAT",
+				Severity: &common.SeverityHint,
+				Range:    section.Header.ToLSPRange(),
+			})
+		}
+	}
+}
+
+func analyzeSymmetricPropertiesSet(
+	ctx *analyzerContext,
+) {
+	for _, section := range ctx.document.Indexes.SectionsByName["Interface"] {
+		preUpProperty := section.FindFirstPropertyByName("PreUp")
+		preDownProperty := section.FindFirstPropertyByName("PreDown")
+
+		postUpProperty := section.FindFirstPropertyByName("PostUp")
+		postDownProperty := section.FindFirstPropertyByName("PostDown")
+
+		if preUpProperty != nil && preDownProperty == nil {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  "PreUp is set, but PreDown is not. It is recommended to set both properties symmetrically",
+				Range:    preUpProperty.ToLSPRange(),
+				Severity: &common.SeverityHint,
+			})
+		} else if preUpProperty == nil && preDownProperty != nil {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  "PreDown is set, but PreUp is not. It is recommended to set both properties symmetrically",
+				Range:    preDownProperty.ToLSPRange(),
+				Severity: &common.SeverityHint,
+			})
+		}
+
+		if postUpProperty != nil && postDownProperty == nil {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  "PostUp is set, but PostDown is not. It is recommended to set both properties symmetrically",
+				Range:    postUpProperty.ToLSPRange(),
+				Severity: &common.SeverityHint,
+			})
+		} else if postUpProperty == nil && postDownProperty != nil {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  "PostDown is set, but PostUp is not. It is recommended to set both properties symmetrically",
+				Range:    postDownProperty.ToLSPRange(),
+				Severity: &common.SeverityHint,
+			})
+		}
+	}
+}
+
+// Strategy
+// Simply compare the host bits of the IP addresses.
+// Use a binary tree to store the host bits.
+func analyzeDuplicateAllowedIPs(
+	ctx *analyzerContext,
+) {
+	ipHostSet := utils.CreateIPv4HostSet()
+
+	for _, section := range ctx.document.Indexes.SectionsByName["Peer"] {
+		property := section.FindFirstPropertyByName("AllowedIPs")
+
+		if property == nil {
+			continue
+		}
+
+		ipAddress, err := netip.ParsePrefix(property.Value.Value)
+
+		if err != nil {
+			// This should not happen...
+			continue
+		}
+
+		if ipContext, _ := ipHostSet.ContainsIP(ipAddress); ipContext != nil {
+			definedLine := (*ipContext).Value("line").(uint32)
+
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  fmt.Sprintf("This IP range is already covered on line %d", definedLine+1),
+				Severity: &common.SeverityError,
+				Range:    property.ToLSPRange(),
+			})
+		} else {
+			ipContext := context.WithValue(context.Background(), "line", property.Start.Line)
+
+			ipHostSet.AddIP(
+				ipAddress,
+				ipContext,
+			)
+		}
+	}
+}
diff --git a/server/handlers/wireguard/analyzer/section.go b/server/handlers/wireguard/analyzer/section.go
new file mode 100644
index 0000000..2587183
--- /dev/null
+++ b/server/handlers/wireguard/analyzer/section.go
@@ -0,0 +1,18 @@
+package analyzer
+
+import (
+	"config-lsp/common"
+
+	protocol "github.com/tliron/glsp/protocol_3_16"
+)
+
+func analyzeInterfaceSection(ctx *analyzerContext) {
+	sections := ctx.document.Indexes.SectionsByName["Interface"]
+	if len(sections) > 1 {
+		ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+			Message:  "Only one [Interface] section is allowed",
+			Severity: &common.SeverityError,
+			Range:    sections[1].Header.ToLSPRange(),
+		})
+	}
+}
diff --git a/server/handlers/wireguard/analyzer/structure.go b/server/handlers/wireguard/analyzer/structure.go
new file mode 100644
index 0000000..58a9c9e
--- /dev/null
+++ b/server/handlers/wireguard/analyzer/structure.go
@@ -0,0 +1,83 @@
+package analyzer
+
+import (
+	"config-lsp/common"
+	"config-lsp/handlers/wireguard/ast"
+	"config-lsp/handlers/wireguard/fields"
+	"config-lsp/utils"
+	"fmt"
+
+	protocol "github.com/tliron/glsp/protocol_3_16"
+)
+
+func analyzeStructureIsValid(ctx *analyzerContext) {
+	for _, section := range ctx.document.Config.Sections {
+		// Whether to check if the property is allowed in the section
+		checkAllowedProperty := true
+
+		if section.Header.Name == "" {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  "This section is missing a name",
+				Range:    section.Header.ToLSPRange(),
+				Severity: &common.SeverityError,
+			})
+		} else if !utils.KeyExists(fields.OptionsHeaderMap, section.Header.Name) {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  fmt.Sprintf("Unknown section '%s'. It must be one of: [Interface], [Peer]", section.Header.Name),
+				Range:    section.Header.ToLSPRange(),
+				Severity: &common.SeverityError,
+			})
+			// Do not check as the section is unknown
+			checkAllowedProperty = false
+		}
+
+		if len(section.Properties) == 0 {
+			ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+				Message:  "This section is empty",
+				Range:    section.Header.ToLSPRange(),
+				Severity: &common.SeverityInformation,
+				Tags: []protocol.DiagnosticTag{
+					protocol.DiagnosticTagUnnecessary,
+				},
+			})
+		} else {
+			existingProperties := make(map[string]*ast.WGProperty)
+
+			for _, property := range section.Properties {
+				if property.Key.Name == "" {
+					ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+						Message:  "This property is missing a name",
+						Range:    property.Key.ToLSPRange(),
+						Severity: &common.SeverityError,
+					})
+				}
+
+				if property.Value == nil || property.Value.Value == "" {
+					ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+						Message:  "This property is missing a value",
+						Range:    property.Value.ToLSPRange(),
+						Severity: &common.SeverityError,
+					})
+				}
+
+				if checkAllowedProperty {
+					options := fields.OptionsHeaderMap[section.Header.Name]
+
+					if !utils.KeyExists(options, property.Key.Name) {
+						ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+							Message:  fmt.Sprintf("Unknown property '%s'", property.Key.Name),
+							Range:    property.Key.ToLSPRange(),
+							Severity: &common.SeverityError,
+						})
+					} else if existingProperty, found := existingProperties[property.Key.Name]; found {
+						ctx.diagnostics = append(ctx.diagnostics, protocol.Diagnostic{
+							Message:  fmt.Sprintf("Property '%s' has already been defined on line %d", property.Key.Name, existingProperty.Start.Line+1),
+							Severity: &common.SeverityError,
+							Range:    existingProperty.ToLSPRange(),
+						})
+					}
+				}
+			}
+		}
+	}
+}