Merge pull request #6 from karol-broda/feat/reverse-dns-lookup

- Switch to nixos-25.11 for modern apple-sdk packages
- Use apple-sdk_15 which includes SecTrustCopyCertificateChain (macOS 12+)
- Required for Go 1.25 crypto/x509 compatibility on darwin

.github/workflows/ci.yaml

@@ -36,3 +36,21 @@ jobs:
         with:
           version: latest
 
+  nix-build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-14]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: DeterminateSystems/nix-installer-action@v17
+
+      - uses: DeterminateSystems/magic-nix-cache-action@v9
+
+      - name: nix flake check
+        run: nix flake check
+
+      - name: nix build
+        run: nix build
+

cmd/cli_test.go

@@ -6,7 +6,7 @@ import (
 	"strings"
 	"testing"
 
-	"snitch/internal/testutil"
+	"github.com/karol-broda/snitch/internal/testutil"
 )
 
 // TestCLIContract tests the CLI interface contracts as specified in the README
@@ -71,7 +71,7 @@ func TestCLIContract(t *testing.T) {
 			name:           "version",
 			args:           []string{"version"},
 			expectExitCode: 0,
-			expectStdout:   []string{"snitch", "commit:", "built:"},
+			expectStdout:   []string{"snitch", "commit", "built"},
 			expectStderr:   nil,
 			description:    "version command should show version information",
 		},
@@ -364,7 +364,8 @@ func resetGlobalFlags() {
 	filterIPv4 = false
 	filterIPv6 = false
 	colorMode = "auto"
-	numeric = false
+	resolveAddrs = true
+	resolvePorts = false
 }
 
 // TestEnvironmentVariables tests that environment variables are properly handled

cmd/golden_test.go

@@ -9,8 +9,8 @@ import (
 	"strings"
 	"testing"
 
-	"snitch/internal/collector"
-	"snitch/internal/testutil"
+	"github.com/karol-broda/snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/testutil"
 )
 
 var updateGolden = flag.Bool("update-golden", false, "Update golden files")

cmd/ls.go

@@ -8,10 +8,10 @@ import (
 	"log"
 	"os"
 	"os/exec"
-	"snitch/internal/collector"
-	"snitch/internal/color"
-	"snitch/internal/config"
-	"snitch/internal/resolver"
+	"github.com/karol-broda/snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/color"
+	"github.com/karol-broda/snitch/internal/config"
+	"github.com/karol-broda/snitch/internal/resolver"
 	"strconv"
 	"strings"
 	"text/tabwriter"
@@ -30,7 +30,8 @@ var (
 	sortBy        string
 	fields        string
 	colorMode     string
-	numeric       bool
+	resolveAddrs  bool
+	resolvePorts  bool
 	plainOutput   bool
 )
 
@@ -51,7 +52,7 @@ Available filters:
 }
 
 func runListCommand(outputFormat string, args []string) {
-	rt, err := NewRuntime(args, colorMode, numeric)
+	rt, err := NewRuntime(args, colorMode)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -98,14 +99,18 @@ func getFieldMap(c collector.Connection) map[string]string {
 	lport := strconv.Itoa(c.Lport)
 	rport := strconv.Itoa(c.Rport)
 	
-	// Apply name resolution if not in numeric mode
-	if !numeric {
+	// apply address resolution
+	if resolveAddrs {
 		if resolvedLaddr := resolver.ResolveAddr(c.Laddr); resolvedLaddr != c.Laddr {
 			laddr = resolvedLaddr
 		}
 		if resolvedRaddr := resolver.ResolveAddr(c.Raddr); resolvedRaddr != c.Raddr && c.Raddr != "*" && c.Raddr != "" {
 			raddr = resolvedRaddr
 		}
+	}
+
+	// apply port resolution
+	if resolvePorts {
 		if resolvedLport := resolver.ResolvePort(c.Lport, c.Proto); resolvedLport != strconv.Itoa(c.Lport) {
 			lport = resolvedLport
 		}
@@ -395,7 +400,8 @@ func init() {
 	lsCmd.Flags().StringVarP(&sortBy, "sort", "s", cfg.Defaults.SortBy, "Sort by column (e.g., pid:desc)")
 	lsCmd.Flags().StringVarP(&fields, "fields", "f", strings.Join(cfg.Defaults.Fields, ","), "Comma-separated list of fields to show")
 	lsCmd.Flags().StringVar(&colorMode, "color", cfg.Defaults.Color, "Color mode (auto, always, never)")
-	lsCmd.Flags().BoolVarP(&numeric, "numeric", "n", cfg.Defaults.Numeric, "Don't resolve hostnames")
+	lsCmd.Flags().BoolVar(&resolveAddrs, "resolve-addrs", !cfg.Defaults.Numeric, "Resolve IP addresses to hostnames")
+	lsCmd.Flags().BoolVar(&resolvePorts, "resolve-ports", false, "Resolve port numbers to service names")
 	lsCmd.Flags().BoolVarP(&plainOutput, "plain", "p", false, "Plain output (parsable, no styling)")
 
 	// shared filter flags

cmd/ls_test.go

@@ -4,8 +4,8 @@ import (
 	"strings"
 	"testing"
 
-	"snitch/internal/collector"
-	"snitch/internal/testutil"
+	"github.com/karol-broda/snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/testutil"
 )
 
 func TestLsCommand_EmptyResults(t *testing.T) {

cmd/root.go

@@ -3,7 +3,7 @@ package cmd
 import (
 	"fmt"
 	"os"
-	"snitch/internal/config"
+	"github.com/karol-broda/snitch/internal/config"
 
 	"github.com/spf13/cobra"
 )
@@ -44,6 +44,8 @@ func init() {
 	cfg := config.Get()
 	rootCmd.Flags().StringVar(&topTheme, "theme", cfg.Defaults.Theme, "Theme for TUI (dark, light, mono, auto)")
 	rootCmd.Flags().DurationVarP(&topInterval, "interval", "i", 0, "Refresh interval (default 1s)")
+	rootCmd.Flags().BoolVar(&topResolveAddrs, "resolve-addrs", !cfg.Defaults.Numeric, "Resolve IP addresses to hostnames")
+	rootCmd.Flags().BoolVar(&topResolvePorts, "resolve-ports", false, "Resolve port numbers to service names")
 
 	// shared filter flags for root command
 	addFilterFlags(rootCmd)

cmd/runtime.go

@@ -2,8 +2,8 @@ package cmd
 
 import (
 	"fmt"
-	"snitch/internal/collector"
-	"snitch/internal/color"
+	"github.com/karol-broda/snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/color"
 	"strconv"
 	"strings"
 
@@ -21,7 +21,8 @@ type Runtime struct {
 
 	// common settings
 	ColorMode    string
-	Numeric   bool
+	ResolveAddrs bool
+	ResolvePorts bool
 }
 
 // shared filter flags - used by all commands
@@ -73,7 +74,7 @@ func FetchConnections(filters collector.FilterOptions) ([]collector.Connection,
 }
 
 // NewRuntime creates a runtime with fetched and filtered connections.
-func NewRuntime(args []string, colorMode string, numeric bool) (*Runtime, error) {
+func NewRuntime(args []string, colorMode string) (*Runtime, error) {
 	color.Init(colorMode)
 
 	filters, err := BuildFilters(args)
@@ -90,7 +91,8 @@ func NewRuntime(args []string, colorMode string, numeric bool) (*Runtime, error)
 		Filters:      filters,
 		Connections:  connections,
 		ColorMode:    colorMode,
-		Numeric:     numeric,
+		ResolveAddrs: resolveAddrs,
+		ResolvePorts: resolvePorts,
 	}, nil
 }
 

cmd/stats.go

@@ -8,7 +8,7 @@ import (
 	"log"
 	"os"
 	"os/signal"
-	"snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/collector"
 	"sort"
 	"strconv"
 	"strings"

cmd/top.go

@@ -2,8 +2,8 @@ package cmd
 
 import (
 	"log"
-	"snitch/internal/config"
-	"snitch/internal/tui"
+	"github.com/karol-broda/snitch/internal/config"
+	"github.com/karol-broda/snitch/internal/tui"
 	"time"
 
 	tea "github.com/charmbracelet/bubbletea"
@@ -14,6 +14,8 @@ import (
 var (
 	topTheme        string
 	topInterval     time.Duration
+	topResolveAddrs bool
+	topResolvePorts bool
 )
 
 var topCmd = &cobra.Command{
@@ -30,6 +32,8 @@ var topCmd = &cobra.Command{
 		opts := tui.Options{
 			Theme:        theme,
 			Interval:     topInterval,
+			ResolveAddrs: topResolveAddrs,
+			ResolvePorts: topResolvePorts,
 		}
 
 		// if any filter flag is set, use exclusive mode
@@ -58,6 +62,8 @@ func init() {
 	// top-specific flags
 	topCmd.Flags().StringVar(&topTheme, "theme", cfg.Defaults.Theme, "Theme for TUI (dark, light, mono, auto)")
 	topCmd.Flags().DurationVarP(&topInterval, "interval", "i", time.Second, "Refresh interval")
+	topCmd.Flags().BoolVar(&topResolveAddrs, "resolve-addrs", !cfg.Defaults.Numeric, "Resolve IP addresses to hostnames")
+	topCmd.Flags().BoolVar(&topResolvePorts, "resolve-ports", false, "Resolve port numbers to service names")
 
 	// shared filter flags
 	addFilterFlags(topCmd)

cmd/trace.go

@@ -7,8 +7,8 @@ import (
 	"log"
 	"os"
 	"os/signal"
-	"snitch/internal/collector"
-	"snitch/internal/resolver"
+	"github.com/karol-broda/snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/resolver"
 	"strings"
 	"syscall"
 	"time"

cmd/upgrade.go

@@ -8,13 +8,17 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"os/exec"
 	"path/filepath"
+	"regexp"
 	"runtime"
 	"strconv"
 	"strings"
 
 	"github.com/fatih/color"
 	"github.com/spf13/cobra"
+
+	"github.com/karol-broda/snitch/internal/tui"
 )
 
 const (
@@ -50,10 +54,26 @@ type githubRelease struct {
 	HTMLURL string `json:"html_url"`
 }
 
+type githubCommit struct {
+	SHA string `json:"sha"`
+}
+
+type githubCompare struct {
+	Status      string `json:"status"`
+	AheadBy     int    `json:"ahead_by"`
+	BehindBy    int    `json:"behind_by"`
+	TotalCommits int   `json:"total_commits"`
+}
+
 func runUpgrade(cmd *cobra.Command, args []string) error {
 	current := Version
+	nixInstall := isNixInstall()
+	nixVersion := isNixVersion(current)
 
 	if upgradeVersion != "" {
+		if nixInstall || nixVersion {
+			return handleNixSpecificVersion(current, upgradeVersion)
+		}
 		return handleSpecificVersion(current, upgradeVersion)
 	}
 
@@ -62,6 +82,10 @@ func runUpgrade(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("failed to check for updates: %w", err)
 	}
 
+	if nixInstall || nixVersion {
+		return handleNixUpgrade(current, latest)
+	}
+
 	currentClean := strings.TrimPrefix(current, "v")
 	latestClean := strings.TrimPrefix(latest, "v")
 
@@ -69,13 +93,13 @@ func runUpgrade(cmd *cobra.Command, args []string) error {
 
 	if currentClean == latestClean {
 		green := color.New(color.FgGreen)
-		green.Println("✓ you are running the latest version")
+		green.Println(tui.SymbolSuccess + " you are running the latest version")
 		return nil
 	}
 
 	if current == "dev" {
 		yellow := color.New(color.FgYellow)
-		yellow.Println("⚠ you are running a development build")
+		yellow.Println(tui.SymbolWarning + " you are running a development build")
 		fmt.Println()
 		fmt.Println("use one of the methods below to install a release version:")
 		fmt.Println()
@@ -84,7 +108,7 @@ func runUpgrade(cmd *cobra.Command, args []string) error {
 	}
 
 	green := color.New(color.FgGreen, color.Bold)
-	green.Printf("✓ update available: %s → %s\n", current, latest)
+	green.Printf(tui.SymbolSuccess+" update available: %s "+tui.SymbolArrowRight+" %s\n", current, latest)
 	fmt.Println()
 
 	if !upgradeYes {
@@ -110,7 +134,7 @@ func handleSpecificVersion(current, target string) error {
 
 	if isVersionLower(targetClean, firstUpgradeVersion) {
 		yellow := color.New(color.FgYellow)
-		yellow.Printf("⚠ warning: the upgrade command was introduced in v%s\n", firstUpgradeVersion)
+		yellow.Printf(tui.SymbolWarning+" warning: the upgrade command was introduced in v%s\n", firstUpgradeVersion)
 		faint := color.New(color.Faint)
 		faint.Printf("  version %s does not include this command\n", target)
 		faint.Println("  you will need to use other methods to upgrade from that version")
@@ -120,7 +144,7 @@ func handleSpecificVersion(current, target string) error {
 	currentClean := strings.TrimPrefix(current, "v")
 	if currentClean == targetClean {
 		green := color.New(color.FgGreen)
-		green.Println("✓ you are already running this version")
+		green.Println(tui.SymbolSuccess + " you are already running this version")
 		return nil
 	}
 
@@ -129,10 +153,10 @@ func handleSpecificVersion(current, target string) error {
 		cmdStyle := color.New(color.FgCyan)
 		if isVersionLower(targetClean, currentClean) {
 			yellow := color.New(color.FgYellow)
-			yellow.Printf("↓ this will downgrade from %s to %s\n", current, target)
+			yellow.Printf(tui.SymbolArrowDown+" this will downgrade from %s to %s\n", current, target)
 		} else {
 			green := color.New(color.FgGreen)
-			green.Printf("↑ this will upgrade from %s to %s\n", current, target)
+			green.Printf(tui.SymbolArrowUp+" this will upgrade from %s to %s\n", current, target)
 		}
 		fmt.Println()
 		faint.Print("run ")
@@ -144,6 +168,136 @@ func handleSpecificVersion(current, target string) error {
 	return performUpgrade(target)
 }
 
+func handleNixUpgrade(current, latest string) error {
+	faint := color.New(color.Faint)
+	version := color.New(color.FgCyan)
+
+	currentCommit := extractCommitFromVersion(current)
+	dirty := isNixDirty(current)
+
+	faint.Print("current  ")
+	version.Print(current)
+	if currentCommit != "" {
+		faint.Printf(" (commit %s)", currentCommit)
+	}
+	fmt.Println()
+
+	faint.Print("latest   ")
+	version.Println(latest)
+	fmt.Println()
+
+	if dirty {
+		yellow := color.New(color.FgYellow)
+		yellow.Println(tui.SymbolWarning + " you are running a dirty nix build (uncommitted changes)")
+		fmt.Println()
+		printNixUpgradeInstructions()
+		return nil
+	}
+
+	if currentCommit == "" {
+		yellow := color.New(color.FgYellow)
+		yellow.Println(tui.SymbolWarning + " this is a nix installation")
+		faint.Println("  nix store is immutable; use nix commands to upgrade")
+		fmt.Println()
+		printNixUpgradeInstructions()
+		return nil
+	}
+
+	releaseCommit, err := fetchCommitForTag(latest)
+	if err != nil {
+		faint.Printf("  (could not fetch release commit: %v)\n", err)
+		fmt.Println()
+		yellow := color.New(color.FgYellow)
+		yellow.Println(tui.SymbolWarning + " this is a nix installation")
+		faint.Println("  nix store is immutable; use nix commands to upgrade")
+		fmt.Println()
+		printNixUpgradeInstructions()
+		return nil
+	}
+
+	releaseShort := releaseCommit
+	if len(releaseShort) > 7 {
+		releaseShort = releaseShort[:7]
+	}
+
+	if strings.HasPrefix(releaseCommit, currentCommit) || strings.HasPrefix(currentCommit, releaseShort) {
+		green := color.New(color.FgGreen)
+		green.Printf(tui.SymbolSuccess+" you are running %s (commit %s)\n", latest, releaseShort)
+		return nil
+	}
+
+	comparison, err := compareCommits(latest, currentCommit)
+	if err != nil {
+		green := color.New(color.FgGreen, color.Bold)
+		green.Printf(tui.SymbolSuccess+" update available: %s "+tui.SymbolArrowRight+" %s\n", currentCommit, latest)
+		faint.Printf("  your commit: %s\n", currentCommit)
+		faint.Printf("  release:     %s (%s)\n", releaseShort, latest)
+		fmt.Println()
+		yellow := color.New(color.FgYellow)
+		yellow.Println(tui.SymbolWarning + " this is a nix installation")
+		faint.Println("  nix store is immutable; use nix commands to upgrade")
+		fmt.Println()
+		printNixUpgradeInstructions()
+		return nil
+	}
+
+	if comparison.AheadBy > 0 {
+		cyan := color.New(color.FgCyan)
+		cyan.Printf(tui.SymbolArrowUp+" you are %d commit(s) ahead of %s\n", comparison.AheadBy, latest)
+		faint.Printf("  your commit: %s\n", currentCommit)
+		faint.Printf("  release:     %s (%s)\n", releaseShort, latest)
+		fmt.Println()
+		faint.Println("you are running a newer build than the latest release")
+		return nil
+	}
+
+	if comparison.BehindBy > 0 {
+		green := color.New(color.FgGreen, color.Bold)
+		green.Printf(tui.SymbolSuccess+" update available: %d commit(s) behind %s\n", comparison.BehindBy, latest)
+		faint.Printf("  your commit: %s\n", currentCommit)
+		faint.Printf("  release:     %s (%s)\n", releaseShort, latest)
+		fmt.Println()
+		yellow := color.New(color.FgYellow)
+		yellow.Println(tui.SymbolWarning + " this is a nix installation")
+		faint.Println("  nix store is immutable; use nix commands to upgrade")
+		fmt.Println()
+		printNixUpgradeInstructions()
+		return nil
+	}
+
+	green := color.New(color.FgGreen)
+	green.Printf(tui.SymbolSuccess+" you are running %s (commit %s)\n", latest, releaseShort)
+	return nil
+}
+
+func handleNixSpecificVersion(current, target string) error {
+	if !strings.HasPrefix(target, "v") {
+		target = "v" + target
+	}
+
+	printVersionComparisonTarget(current, target)
+
+	yellow := color.New(color.FgYellow)
+	yellow.Println(tui.SymbolWarning + " this is a nix installation")
+	faint := color.New(color.Faint)
+	faint.Println("  nix store is immutable; in-place upgrades are not supported")
+	fmt.Println()
+
+	bold := color.New(color.Bold)
+	cmd := color.New(color.FgCyan)
+
+	bold.Println("to install a specific version with nix:")
+	fmt.Println()
+
+	faint.Print("  specific ref    ")
+	cmd.Printf("nix profile install github:%s/%s/%s\n", repoOwner, repoName, target)
+
+	faint.Print("  latest          ")
+	cmd.Printf("nix profile install github:%s/%s\n", repoOwner, repoName)
+
+	return nil
+}
+
 func isVersionLower(v1, v2 string) bool {
 	parts1 := parseVersion(v1)
 	parts2 := parseVersion(v2)
@@ -251,6 +405,14 @@ func performUpgrade(version string) error {
 		return fmt.Errorf("failed to resolve executable path: %w", err)
 	}
 
+	if strings.HasPrefix(execPath, "/nix/store/") {
+		yellow := color.New(color.FgYellow)
+		yellow.Println(tui.SymbolWarning + " cannot perform in-place upgrade for nix installation")
+		fmt.Println()
+		printNixUpgradeInstructions()
+		return nil
+	}
+
 	goos := runtime.GOOS
 	goarch := runtime.GOARCH
 
@@ -261,7 +423,7 @@ func performUpgrade(version string) error {
 
 	faint := color.New(color.Faint)
 	cyan := color.New(color.FgCyan)
-	faint.Print("↓ downloading ")
+	faint.Print(tui.SymbolDownload + " downloading ")
 	cyan.Printf("%s", archiveName)
 	faint.Println("...")
 
@@ -286,13 +448,17 @@ func performUpgrade(version string) error {
 		return fmt.Errorf("failed to extract binary: %w", err)
 	}
 
+	if goos == "darwin" {
+		removeQuarantine(binaryPath)
+	}
+
 	// check if we can write to the target location
 	targetDir := filepath.Dir(execPath)
 	if !isWritable(targetDir) {
 		yellow := color.New(color.FgYellow)
 		cmdStyle := color.New(color.FgCyan)
 
-		yellow.Printf("⚠ elevated permissions required to install to %s\n", targetDir)
+		yellow.Printf(tui.SymbolWarning+" elevated permissions required to install to %s\n", targetDir)
 		fmt.Println()
 		faint.Println("run with sudo or install to a user-writable location:")
 		fmt.Println()
@@ -325,11 +491,11 @@ func performUpgrade(version string) error {
 	if err := os.Remove(backupPath); err != nil {
 		// non-fatal, just warn
 		yellow := color.New(color.FgYellow)
-		yellow.Fprintf(os.Stderr, "⚠ warning: failed to remove backup file %s: %v\n", backupPath, err)
+		yellow.Fprintf(os.Stderr, tui.SymbolWarning + " warning: failed to remove backup file %s: %v\n", backupPath, err)
 	}
 
 	green := color.New(color.FgGreen, color.Bold)
-	green.Printf("✓ successfully upgraded to %s\n", version)
+	green.Printf(tui.SymbolSuccess + " successfully upgraded to %s\n", version)
 	return nil
 }
 
@@ -410,3 +576,113 @@ func copyFile(src, dst string) error {
 	return dstFile.Sync()
 }
 
+func removeQuarantine(path string) {
+	cmd := exec.Command("xattr", "-d", "com.apple.quarantine", path)
+	if err := cmd.Run(); err == nil {
+		faint := color.New(color.Faint)
+		faint.Println("  removed macOS quarantine attribute")
+	}
+}
+
+func isNixInstall() bool {
+	execPath, err := os.Executable()
+	if err != nil {
+		return false
+	}
+
+	resolved, err := filepath.EvalSymlinks(execPath)
+	if err != nil {
+		return false
+	}
+
+	return strings.HasPrefix(resolved, "/nix/store/")
+}
+
+var nixVersionPattern = regexp.MustCompile(`^nix-([a-f0-9]+)(-dirty)?$`)
+var commitHashPattern = regexp.MustCompile(`^[a-f0-9]{7,40}$`)
+
+func isNixVersion(version string) bool {
+	if nixVersionPattern.MatchString(version) {
+		return true
+	}
+	if commitHashPattern.MatchString(version) {
+		return true
+	}
+	return false
+}
+
+func extractCommitFromVersion(version string) string {
+	matches := nixVersionPattern.FindStringSubmatch(version)
+	if len(matches) >= 2 {
+		return matches[1]
+	}
+	if commitHashPattern.MatchString(version) {
+		return version
+	}
+	return ""
+}
+
+func isNixDirty(version string) bool {
+	return strings.HasSuffix(version, "-dirty")
+}
+
+func fetchCommitForTag(tag string) (string, error) {
+	url := fmt.Sprintf("%s/repos/%s/%s/commits/%s", githubAPI, repoOwner, repoName, tag)
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("github api returned status %d", resp.StatusCode)
+	}
+
+	var commit githubCommit
+	if err := json.NewDecoder(resp.Body).Decode(&commit); err != nil {
+		return "", err
+	}
+
+	return commit.SHA, nil
+}
+
+func compareCommits(base, head string) (*githubCompare, error) {
+	url := fmt.Sprintf("%s/repos/%s/%s/compare/%s...%s", githubAPI, repoOwner, repoName, base, head)
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("github api returned status %d", resp.StatusCode)
+	}
+
+	var compare githubCompare
+	if err := json.NewDecoder(resp.Body).Decode(&compare); err != nil {
+		return nil, err
+	}
+
+	return &compare, nil
+}
+
+func printNixUpgradeInstructions() {
+	bold := color.New(color.Bold)
+	faint := color.New(color.Faint)
+	cmd := color.New(color.FgCyan)
+
+	bold.Println("nix upgrade options:")
+	fmt.Println()
+
+	faint.Print("  flake profile   ")
+	cmd.Printf("nix profile install github:%s/%s\n", repoOwner, repoName)
+
+	faint.Print("  flake update    ")
+	cmd.Println("nix flake update snitch  (in your system/home-manager config)")
+
+	faint.Print("  rebuild         ")
+	cmd.Println("nixos-rebuild switch  or  home-manager switch")
+}
+

cmd/version.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"runtime"
 
+	"github.com/fatih/color"
 	"github.com/spf13/cobra"
 )
 
@@ -17,11 +18,25 @@ var versionCmd = &cobra.Command{
 	Use:   "version",
 	Short: "Show version/build info",
 	Run: func(cmd *cobra.Command, args []string) {
-		fmt.Printf("snitch %s\n", Version)
-		fmt.Printf("  commit: %s\n", Commit)
-		fmt.Printf("  built:  %s\n", Date)
-		fmt.Printf("  go:     %s\n", runtime.Version())
-		fmt.Printf("  os:     %s/%s\n", runtime.GOOS, runtime.GOARCH)
+		bold := color.New(color.Bold)
+		cyan := color.New(color.FgCyan)
+		faint := color.New(color.Faint)
+
+		bold.Print("snitch ")
+		cyan.Println(Version)
+		fmt.Println()
+
+		faint.Print("  commit  ")
+		fmt.Println(Commit)
+
+		faint.Print("  built   ")
+		fmt.Println(Date)
+
+		faint.Print("  go      ")
+		fmt.Println(runtime.Version())
+
+		faint.Print("  os      ")
+		fmt.Printf("%s/%s\n", runtime.GOOS, runtime.GOARCH)
 	},
 }
 

flake.lock

@@ -2,16 +2,16 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1765687488,
-        "narHash": "sha256-7YAJ6xgBAQ/Nr+7MI13Tui1ULflgAdKh63m1tfYV7+M=",
+        "lastModified": 1766201043,
+        "narHash": "sha256-eplAP+rorKKd0gNjV3rA6+0WMzb1X1i16F5m5pASnjA=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "d02bcc33948ca19b0aaa0213fe987ceec1f4ebe1",
+        "rev": "b3aad468604d3e488d627c0b43984eb60e75e782",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-25.05",
+        "ref": "nixos-25.11",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,7 +1,7 @@
 {
   description = "snitch - a friendlier ss/netstat for humans";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
 
   outputs = { self, nixpkgs }:
     let
@@ -46,7 +46,9 @@
 
       mkSnitch = pkgs:
         let
-          version = self.shortRev or self.dirtyShortRev or "dev";
+          rev = self.shortRev or self.dirtyShortRev or "unknown";
+          version = "nix-${rev}";
+          isDarwin = pkgs.stdenv.isDarwin;
           go = mkGo125 pkgs;
           buildGoModule = pkgs.buildGoModule.override { inherit go; };
         in
@@ -55,20 +57,23 @@
           inherit version;
           src = self;
           vendorHash = "sha256-fX3wOqeOgjH7AuWGxPQxJ+wbhp240CW8tiF4rVUUDzk=";
-          env.CGO_ENABLED = "0";
+          # darwin requires cgo for libproc, linux uses pure go with /proc
+          env.CGO_ENABLED = if isDarwin then "1" else "0";
           env.GOTOOLCHAIN = "local";
+          # darwin: use macOS 15 SDK for SecTrustCopyCertificateChain (Go 1.25 crypto/x509)
+          buildInputs = pkgs.lib.optionals isDarwin [ pkgs.apple-sdk_15 ];
           ldflags = [
             "-s"
             "-w"
             "-X snitch/cmd.Version=${version}"
-            "-X snitch/cmd.Commit=${version}"
+            "-X snitch/cmd.Commit=${rev}"
             "-X snitch/cmd.Date=${self.lastModifiedDate or "unknown"}"
           ];
           meta = {
             description = "a friendlier ss/netstat for humans";
             homepage = "https://github.com/karol-broda/snitch";
             license = pkgs.lib.licenses.mit;
-            platforms = pkgs.lib.platforms.linux;
+            platforms = pkgs.lib.platforms.linux ++ pkgs.lib.platforms.darwin;
             mainProgram = "snitch";
           };
         };

go.mod

@@ -1,4 +1,4 @@
-module snitch
+module github.com/karol-broda/snitch
 
 go 1.24.0
 

internal/testutil/testutil.go

@@ -5,7 +5,7 @@ import (
 	"path/filepath"
 	"testing"
 
-	"snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/collector"
 )
 
 // TestCollector wraps MockCollector for use in tests

internal/tui/helpers.go

@@ -1,9 +1,8 @@
 package tui
 
 import (
-	"fmt"
 	"regexp"
-	"snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/collector"
 	"strings"
 )
 
@@ -44,10 +43,3 @@ func sortFieldLabel(f collector.SortField) string {
 	}
 }
 
-func formatRemote(addr string, port int) string {
-	if addr == "" || addr == "*" || port == 0 {
-		return "-"
-	}
-	return fmt.Sprintf("%s:%d", addr, port)
-}
-

internal/tui/keys.go

@@ -2,7 +2,7 @@ package tui
 
 import (
 	"fmt"
-	"snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/collector"
 	"time"
 
 	tea "github.com/charmbracelet/bubbletea"
@@ -210,6 +210,28 @@ func (m model) handleNormalKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 				m.showKillConfirm = true
 			}
 		}
+
+	// toggle address resolution
+	case "n":
+		m.resolveAddrs = !m.resolveAddrs
+		if m.resolveAddrs {
+			m.statusMessage = "address resolution: on"
+		} else {
+			m.statusMessage = "address resolution: off"
+		}
+		m.statusExpiry = time.Now().Add(2 * time.Second)
+		return m, clearStatusAfter(2 * time.Second)
+
+	// toggle port resolution
+	case "N":
+		m.resolvePorts = !m.resolvePorts
+		if m.resolvePorts {
+			m.statusMessage = "port resolution: on"
+		} else {
+			m.statusMessage = "port resolution: off"
+		}
+		m.statusExpiry = time.Now().Add(2 * time.Second)
+		return m, clearStatusAfter(2 * time.Second)
 	}
 
 	return m, nil

internal/tui/messages.go

@@ -2,7 +2,7 @@ package tui
 
 import (
 	"fmt"
-	"snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/collector"
 	"syscall"
 	"time"
 

internal/tui/model.go

@@ -2,8 +2,8 @@ package tui
 
 import (
 	"fmt"
-	"snitch/internal/collector"
-	"snitch/internal/theme"
+	"github.com/karol-broda/snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/theme"
 	"time"
 
 	tea "github.com/charmbracelet/bubbletea"
@@ -28,6 +28,10 @@ type model struct {
 	sortField   collector.SortField
 	sortReverse bool
 
+	// display options
+	resolveAddrs bool // when true, resolve IP addresses to hostnames
+	resolvePorts bool // when true, resolve port numbers to service names
+
 	// ui state
 	theme       *theme.Theme
 	showHelp    bool
@@ -58,6 +62,8 @@ type Options struct {
 	Established  bool
 	Other        bool
 	FilterSet    bool // true if user specified any filter flags
+	ResolveAddrs bool // when true, resolve IP addresses to hostnames
+	ResolvePorts bool // when true, resolve port numbers to service names
 }
 
 func New(opts Options) model {
@@ -102,6 +108,8 @@ func New(opts Options) model {
 		showEstablished: showEstablished,
 		showOther:       showOther,
 		sortField:       collector.SortByLport,
+		resolveAddrs:    opts.ResolveAddrs,
+		resolvePorts:    opts.ResolvePorts,
 		theme:           theme.GetTheme(opts.Theme),
 		interval:        interval,
 		lastRefresh:     time.Now(),

internal/tui/model_test.go

@@ -1,7 +1,7 @@
 package tui
 
 import (
-	"snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/collector"
 	"testing"
 	"time"
 
@@ -301,3 +301,132 @@ func TestTUI_ViewRenders(t *testing.T) {
 	}
 }
 
+func TestTUI_ResolutionOptions(t *testing.T) {
+	// test default resolution settings
+	m := New(Options{Theme: "dark", Interval: time.Hour})
+
+	if m.resolveAddrs != false {
+		t.Error("expected resolveAddrs to be false by default (must be explicitly set)")
+	}
+	if m.resolvePorts != false {
+		t.Error("expected resolvePorts to be false by default")
+	}
+
+	// test with explicit options
+	m2 := New(Options{
+		Theme:        "dark",
+		Interval:     time.Hour,
+		ResolveAddrs: true,
+		ResolvePorts: true,
+	})
+
+	if m2.resolveAddrs != true {
+		t.Error("expected resolveAddrs to be true when set")
+	}
+	if m2.resolvePorts != true {
+		t.Error("expected resolvePorts to be true when set")
+	}
+}
+
+func TestTUI_ToggleResolution(t *testing.T) {
+	m := New(Options{Theme: "dark", Interval: time.Hour, ResolveAddrs: true})
+
+	if m.resolveAddrs != true {
+		t.Fatal("expected resolveAddrs to be true initially")
+	}
+
+	// toggle address resolution with 'n'
+	newModel, _ := m.Update(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{'n'}})
+	m = newModel.(model)
+
+	if m.resolveAddrs != false {
+		t.Error("expected resolveAddrs to be false after toggle")
+	}
+
+	// toggle back
+	newModel, _ = m.Update(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{'n'}})
+	m = newModel.(model)
+
+	if m.resolveAddrs != true {
+		t.Error("expected resolveAddrs to be true after second toggle")
+	}
+
+	// toggle port resolution with 'N'
+	if m.resolvePorts != false {
+		t.Fatal("expected resolvePorts to be false initially")
+	}
+
+	newModel, _ = m.Update(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{'N'}})
+	m = newModel.(model)
+
+	if m.resolvePorts != true {
+		t.Error("expected resolvePorts to be true after toggle")
+	}
+
+	// toggle back
+	newModel, _ = m.Update(tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune{'N'}})
+	m = newModel.(model)
+
+	if m.resolvePorts != false {
+		t.Error("expected resolvePorts to be false after second toggle")
+	}
+}
+
+func TestTUI_ResolveAddrHelper(t *testing.T) {
+	m := New(Options{Theme: "dark", Interval: time.Hour})
+	m.resolveAddrs = false
+
+	// when resolution is off, should return original address
+	addr := m.resolveAddr("192.168.1.1")
+	if addr != "192.168.1.1" {
+		t.Errorf("expected original address when resolution off, got %s", addr)
+	}
+
+	// empty and wildcard addresses should pass through unchanged
+	if m.resolveAddr("") != "" {
+		t.Error("expected empty string to pass through")
+	}
+	if m.resolveAddr("*") != "*" {
+		t.Error("expected wildcard to pass through")
+	}
+}
+
+func TestTUI_ResolvePortHelper(t *testing.T) {
+	m := New(Options{Theme: "dark", Interval: time.Hour})
+	m.resolvePorts = false
+
+	// when resolution is off, should return port number as string
+	port := m.resolvePort(80, "tcp")
+	if port != "80" {
+		t.Errorf("expected '80' when resolution off, got %s", port)
+	}
+
+	port = m.resolvePort(443, "tcp")
+	if port != "443" {
+		t.Errorf("expected '443' when resolution off, got %s", port)
+	}
+}
+
+func TestTUI_FormatRemoteHelper(t *testing.T) {
+	m := New(Options{Theme: "dark", Interval: time.Hour})
+	m.resolveAddrs = false
+	m.resolvePorts = false
+
+	// empty/wildcard addresses should return dash
+	if m.formatRemote("", 80, "tcp") != "-" {
+		t.Error("expected dash for empty address")
+	}
+	if m.formatRemote("*", 80, "tcp") != "-" {
+		t.Error("expected dash for wildcard address")
+	}
+	if m.formatRemote("192.168.1.1", 0, "tcp") != "-" {
+		t.Error("expected dash for zero port")
+	}
+
+	// valid address:port should format correctly
+	result := m.formatRemote("192.168.1.1", 443, "tcp")
+	if result != "192.168.1.1:443" {
+		t.Errorf("expected '192.168.1.1:443', got %s", result)
+	}
+}
+

internal/tui/symbols.go

@@ -15,6 +15,7 @@ const (
 	SymbolArrowDown  = string('\u2193') // downwards arrow
 	SymbolRefresh    = string('\u21BB') // clockwise open circle arrow
 	SymbolEllipsis   = string('\u2026') // horizontal ellipsis
+	SymbolDownload   = string('\u21E9') // downwards white arrow
 
 	// box drawing rounded 
 	BoxTopLeft     = string('\u256D') // light arc down and right

internal/tui/view.go

@@ -2,7 +2,9 @@ package tui
 
 import (
 	"fmt"
-	"snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/collector"
+	"github.com/karol-broda/snitch/internal/resolver"
+	"strconv"
 	"strings"
 	"time"
 
@@ -161,19 +163,19 @@ func (m model) renderRow(c collector.Connection, selected bool) string {
 		process = SymbolDash
 	}
 
-	port := fmt.Sprintf("%d", c.Lport)
+	port := truncate(m.resolvePort(c.Lport, c.Proto), cols.port)
 	proto := c.Proto
 	state := c.State
 	if state == "" {
 		state = SymbolDash
 	}
 
-	local := c.Laddr
+	local := truncate(m.resolveAddr(c.Laddr), cols.local)
 	if local == "*" || local == "" {
 		local = "*"
 	}
 
-	remote := formatRemote(c.Raddr, c.Rport)
+	remote := truncate(m.formatRemote(c.Raddr, c.Rport, c.Proto), cols.remote)
 
 	// apply styling
 	protoStyled := m.theme.Styles.GetProtoStyle(proto).Render(fmt.Sprintf("%-*s", cols.proto, proto))
@@ -185,8 +187,8 @@ func (m model) renderRow(c collector.Connection, selected bool) string {
 		cols.port, port,
 		protoStyled,
 		stateStyled,
-		cols.local, truncate(local, cols.local),
-		truncate(remote, cols.remote))
+		cols.local, local,
+		remote)
 
 	if selected {
 		return m.theme.Styles.Selected.Render(row) + "\n"
@@ -201,7 +203,7 @@ func (m model) renderStatusLine() string {
 		return "  " + m.theme.Styles.Warning.Render(m.statusMessage)
 	}
 
-	left := "  " + m.theme.Styles.Normal.Render("t/u proto  l/e/o state  w watch  K kill  s sort  / search  ? help  q quit")
+	left := "  " + m.theme.Styles.Normal.Render("t/u proto  l/e/o state  n/N dns  w watch  K kill  s sort  / search  ? help  q quit")
 
 	// show watched count if any
 	if m.watchedCount() > 0 {
@@ -209,6 +211,21 @@ func (m model) renderStatusLine() string {
 		left += m.theme.Styles.Watched.Render(watchedInfo)
 	}
 
+	// show dns resolution status
+	var resolveStatus string
+	if m.resolveAddrs && m.resolvePorts {
+		resolveStatus = "all"
+	} else if m.resolveAddrs {
+		resolveStatus = "addrs"
+	} else if m.resolvePorts {
+		resolveStatus = "ports"
+	} else {
+		resolveStatus = "off"
+	}
+	if resolveStatus != "addrs" { // addrs is the default, don't show
+		left += m.theme.Styles.Normal.Render(fmt.Sprintf("  dns: %s", resolveStatus))
+	}
+
 	return left
 }
 
@@ -240,6 +257,11 @@ func (m model) renderHelp() string {
   s            cycle sort field
   S            reverse sort order
 
+  display
+  ───────
+  n            toggle address resolution (dns)
+  N            toggle port resolution (service names)
+
   process management
   ──────────────────
   w            watch/unwatch process (highlight & track)
@@ -269,6 +291,11 @@ func (m model) renderDetail() string {
 	b.WriteString("  " + m.theme.Styles.Header.Render("connection details") + "\n")
 	b.WriteString("  " + m.theme.Styles.Border.Render(strings.Repeat(BoxHorizontal, 40)) + "\n\n")
 
+	localAddr := m.resolveAddr(c.Laddr)
+	localPort := m.resolvePort(c.Lport, c.Proto)
+	remoteAddr := m.resolveAddr(c.Raddr)
+	remotePort := m.resolvePort(c.Rport, c.Proto)
+
 	fields := []struct {
 		label string
 		value string
@@ -278,8 +305,8 @@ func (m model) renderDetail() string {
 		{"user", c.User},
 		{"protocol", c.Proto},
 		{"state", c.State},
-		{"local", fmt.Sprintf("%s:%d", c.Laddr, c.Lport)},
-		{"remote", fmt.Sprintf("%s:%d", c.Raddr, c.Rport)},
+		{"local", fmt.Sprintf("%s:%s", localAddr, localPort)},
+		{"remote", fmt.Sprintf("%s:%s", remoteAddr, remotePort)},
 		{"interface", c.Interface},
 		{"inode", fmt.Sprintf("%d", c.Inode)},
 	}
@@ -498,23 +525,72 @@ type columns struct {
 }
 
 func (m model) columnWidths() columns {
-	available := m.safeWidth() - 16
-
+	// minimum widths (header lengths + padding)
 	c := columns{
-		process: 16,
-		port:    6,
-		proto:   5,
-		state:   11,
-		local:   15,
-		remote:  20,
+		process: 7,  // "PROCESS"
+		port:    4,  // "PORT"
+		proto:   5,  // "PROTO"
+		state:   5,  // "STATE"
+		local:   5,  // "LOCAL"
+		remote:  6,  // "REMOTE"
 	}
 
-	used := c.process + c.port + c.proto + c.state + c.local + c.remote
-	extra := available - used
+	// scan visible connections to find max content width for each column
+	visible := m.visibleConnections()
+	for _, conn := range visible {
+		if len(conn.Process) > c.process {
+			c.process = len(conn.Process)
+		}
 
-	if extra > 0 {
-		c.process += extra / 3
-		c.remote += extra - extra/3
+		port := m.resolvePort(conn.Lport, conn.Proto)
+		if len(port) > c.port {
+			c.port = len(port)
+		}
+
+		if len(conn.Proto) > c.proto {
+			c.proto = len(conn.Proto)
+		}
+
+		if len(conn.State) > c.state {
+			c.state = len(conn.State)
+		}
+
+		local := m.resolveAddr(conn.Laddr)
+		if len(local) > c.local {
+			c.local = len(local)
+		}
+
+		remote := m.formatRemote(conn.Raddr, conn.Rport, conn.Proto)
+		if len(remote) > c.remote {
+			c.remote = len(remote)
+		}
+	}
+
+	// calculate total and available width
+	spacing := 12 // 2 spaces between each of 6 columns
+	indicator := 2
+	margin := 2
+	available := m.safeWidth() - spacing - indicator - margin
+
+	total := c.process + c.port + c.proto + c.state + c.local + c.remote
+
+	// if content fits, we're done
+	if total <= available {
+		return c
+	}
+
+	// content exceeds available space - need to shrink columns proportionally
+	// fixed columns that shouldn't shrink much: port, proto, state
+	fixedWidth := c.port + c.proto + c.state
+	flexibleAvailable := available - fixedWidth
+
+	// distribute flexible space between process, local, remote
+	flexibleTotal := c.process + c.local + c.remote
+	if flexibleTotal > 0 && flexibleAvailable > 0 {
+		ratio := float64(flexibleAvailable) / float64(flexibleTotal)
+		c.process = max(7, int(float64(c.process)*ratio))
+		c.local = max(5, int(float64(c.local)*ratio))
+		c.remote = max(6, int(float64(c.remote)*ratio))
 	}
 
 	return c
@@ -536,3 +612,29 @@ func formatDuration(d time.Duration) string {
 	}
 	return fmt.Sprintf("%.0fm", d.Minutes())
 }
+
+func (m model) resolveAddr(addr string) string {
+	if !m.resolveAddrs {
+		return addr
+	}
+	if addr == "" || addr == "*" {
+		return addr
+	}
+	return resolver.ResolveAddr(addr)
+}
+
+func (m model) resolvePort(port int, proto string) string {
+	if !m.resolvePorts {
+		return strconv.Itoa(port)
+	}
+	return resolver.ResolvePort(port, proto)
+}
+
+func (m model) formatRemote(addr string, port int, proto string) string {
+	if addr == "" || addr == "*" || port == 0 {
+		return "-"
+	}
+	resolvedAddr := m.resolveAddr(addr)
+	resolvedPort := m.resolvePort(port, proto)
+	return fmt.Sprintf("%s:%s", resolvedAddr, resolvedPort)
+}

main.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"snitch/cmd"
+	"github.com/karol-broda/snitch/cmd"
 )
 
 func main() {