1. 在Ionic中，首先需要安装@angular/fire和firebase：

npm install @angular/fire firebase --save

2. 创建一个AuthService来处理Firebase认证：

import { Injectable } from '@angular/core';
import { AngularFireAuth } from '@angular/fire/auth';

@Injectable({
  providedIn: 'root'
})
export class AuthService {

  constructor(private afAuth: AngularFireAuth) { }

  async login(email: string, password: string) {
    try {
      const result = await this.afAuth.signInWithEmailAndPassword(email, password);
      return result;
    } catch (error) {
      console.log(error);
    }
  }

  async register(email: string, password: string) {
    try {
      const result = await this.afAuth.createUserWithEmailAndPassword(email, password);
      return result;
    } catch (error) {
      console.log(error);
    }
  }

  async logout() {
    try {
      await this.afAuth.signOut();
    } catch (error) {
      console.log(error);
    }
  }

}

3. 创建一个AuthGuard来控制访问权限：

import { Injectable } from '@angular/core';
import { CanActivate, Router } from '@angular/router';
import { AuthService } from './auth.service';

@Injectable({
  providedIn: 'root'
})
export class AuthGuard implements CanActivate {

  constructor(private authService: AuthService, private router: Router) {}

  async canActivate(): Promise {
    const user = await this.authService.getCurrentUser();
    if (user) {
      return true;
    } else {
      this.router.navigate(['/login']);
      return false;
    }
  }

}

4. 在需要保护的路由上使用AuthGuard：

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

import { HomePage } from './home.page';
import { AuthGuard } from '../services/auth.guard';

const routes: Routes = [
  {
    path: '',
    component: HomePage,
    canActivate: [AuthGuard]
  }
];

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule],
})
export class HomePageRoutingModule {}