SMB: optional legacy mode (SMB1 + NTLMv1) for old clients

Supermicro BMC virtual media ("CD-ROM image" over a Windows share) only
offers the SMB1 dialect "NT LM 0.12", which Samba rejects with
server min protocol = SMB2. Add an opt-in "Allow legacy clients" SMB
setting that renders server min protocol = NT1 and
ntlm auth = ntlmv1-permitted. Off by default.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/shares.go

@@ -204,6 +204,7 @@ func (s *Server) smbSettings(w http.ResponseWriter, r *http.Request) {
 	c.SMB.Enabled = r.FormValue("enabled") != ""
 	c.SMB.Workgroup = strings.ToUpper(strings.TrimSpace(r.FormValue("workgroup")))
 	c.SMB.ServerString = strings.TrimSpace(r.FormValue("server_string"))
+	c.SMB.Legacy = r.FormValue("legacy") != ""
 	if err := shares.ValidateComment(c.SMB.ServerString); err != nil {
 		s.sharesFail(w, r, "Not saved: server description: "+err.Error(), smbForm{}, nfsForm{})
 		return

internal/web/shares_test.go

@@ -226,3 +226,24 @@ func TestSharesNFSFlow(t *testing.T) {
 		t.Errorf("delete: %d %v", rec.Code, f.calls)
 	}
 }
+
+func TestSharesSMBLegacySetting(t *testing.T) {
+	srv, _, _ := newTestServer(t)
+	f := &shareRunner{users: "alice:1001:\n"}
+	withShareRunner(srv, f)
+	postForm(srv, "/shares/smb/save", url.Values{"name": {"iso"}, "path": {"/tank/data"}, "users": {"alice"}, "browseable": {"1"}})
+	rec := postForm(srv, "/shares/smb/settings", url.Values{"enabled": {"1"}, "workgroup": {"workgroup"}, "server_string": {"NAS"}, "legacy": {"1"}})
+	if rec.Code != http.StatusSeeOther || !srv.shares.Get().SMB.Legacy {
+		t.Fatalf("legacy not saved: %d %s", rec.Code, rec.Body.String())
+	}
+	if conf := f.written(shares.DefaultSMBConf); !strings.Contains(conf, "server min protocol = NT1") {
+		t.Errorf("smb.conf without SMB1:\n%s", conf)
+	}
+	if !strings.Contains(get(srv, "/shares").Body.String(), `name="legacy" value="1" checked`) {
+		t.Errorf("legacy checkbox not shown as checked")
+	}
+	postForm(srv, "/shares/smb/settings", url.Values{"enabled": {"1"}, "workgroup": {"WORKGROUP"}, "server_string": {"NAS"}})
+	if srv.shares.Get().SMB.Legacy || !strings.Contains(f.written(shares.DefaultSMBConf), "server min protocol = SMB2") {
+		t.Errorf("legacy not cleared")
+	}
+}

internal/web/templates/shares.html

@@ -18,6 +18,7 @@
     <label class="check"><input type="checkbox" name="enabled" value="1" {{if .C.SMB.Enabled}}checked{{end}}> SMB server enabled</label>
     <label>Workgroup <input name="workgroup" value="{{.C.SMB.Workgroup}}"></label>
     <label>Description <input name="server_string" value="{{.C.SMB.ServerString}}"></label>
+    <label class="check"><input type="checkbox" name="legacy" value="1" {{if .C.SMB.Legacy}}checked{{end}}> Allow legacy clients (SMB1 + NTLMv1) — IPMI/BMC virtual media, old devices; less secure</label>
     <div class="field"><span class="field-name">&nbsp;</span><span><button type="submit" class="secondary">Save SMB settings</button></span></div>
   </form>