Chapter 10 Firewall
P-870H/HW Series User’s Guide
138
Some of the most common IP ports are:
Default Filtering Policies
Filtering rules are grouped based on the direction of travel of packets to which
they apply.
The default rule for incoming traffic blocks all incoming connections from the WAN
to the LAN. If you wish to allow certain WAN users to have access to your LAN,
you will need to create custom rules to allow it.
Note: If you configure filtering rules without a good understanding of how they work,
you might inadvertently introduce security risks to the firewall and to the
protected network. Make sure you test your rules after you configure them.
These custom rules work by comparing the Source IP address, Destination IP
address and IP protocol type of network traffic to rules set by the administrator.
Your customized rules take precedence and override the ZyXEL Device’s default
rules.
10.3 The Firewall Screen
Click Security > Firewall > Incoming to display the following screen. This
screen displays a list of the configured incoming filtering rules.
Figure 75
Firewall > Incoming
Table 46
Common IP Ports
21
FTP
53
DNS
23
Telnet
80
HTTP
25
SMTP
110
POP3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
