Iptables Tutorial 1.2.2
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- Dedications - Страница 2
- About the author - Страница 3
- How to read - Страница 4
- Prerequisites - Страница 5
- Conventions used in this document - Страница 6
- Chapter 1. Introduction - Страница 7
- How it was written - Страница 8
- Terms used in this document - Страница 9
- What's next? - Страница 10
- Chapter 2. TCP/IP repetition - Страница 11
- TCP/IP Layers - Страница 12
- IP characteristics - Страница 14
- IP headers - Страница 16
- TCP characteristics - Страница 19
- TCP headers - Страница 20
- UDP characteristics - Страница 22
- UDP headers - Страница 23
- ICMP characteristics - Страница 24
- ICMP headers - Страница 25
- ICMP Echo Request/Reply - Страница 26
- ICMP Destination Unreachable - Страница 27
- Source Quench - Страница 28
- Redirect - Страница 29
- TTL equals 0 - Страница 30
- Parameter problem - Страница 31
- Timestamp request/reply - Страница 32
- Information request/reply - Страница 33
- SCTP Characteristics - Страница 34
- Initialization and association - Страница 35
- Data sending and control session - Страница 36
- Shutdown and abort - Страница 37
- SCTP Headers - Страница 38
- SCTP Generic header format - Страница 39
- SCTP Common and generic headers - Страница 40
- SCTP ABORT chunk - Страница 42
- SCTP COOKIE ACK chunk - Страница 43
- SCTP COOKIE ECHO chunk - Страница 44
- SCTP DATA chunk - Страница 45
- SCTP ERROR chunk - Страница 46
- SCTP HEARTBEAT chunk - Страница 47
- SCTP HEARTBEAT ACK chunk - Страница 48
- SCTP INIT chunk - Страница 49
- SCTP INIT ACK chunk - Страница 51
- SCTP SACK chunk - Страница 52
- SCTP SHUTDOWN chunk - Страница 53
- SCTP SHUTDOWN ACK chunk - Страница 54
- SCTP SHUTDOWN COMPLETE chunk - Страница 55
- TCP/IP destination driven routing - Страница 56
- What's next? - Страница 57
- Chapter 3. IP filtering introduction - Страница 58
- What is an IP filter - Страница 59
- IP filtering terms and expressions - Страница 61
- How to plan an IP filter - Страница 63
- What's next? - Страница 65
- Chapter 4. Network Address Translation Introduction - Страница 66
- What NAT is used for and basic terms and expressions - Страница 67
- Caveats using NAT - Страница 68
- Example NAT machine in theory - Страница 69
- What is needed to build a NAT machine - Страница 70
- Placement of NAT machines - Страница 71
- How to place proxies - Страница 72
- The final stage of our NAT machine - Страница 73
- What's next? - Страница 74
- Chapter 5. Preparations - Страница 75
- Where to get iptables - Страница 76
- Kernel setup - Страница 77
- User-land setup - Страница 80
- Compiling the user-land applications - Страница 81
- Installation on Red Hat 7.1 - Страница 82
- What's next? - Страница 84
- Chapter 6. Traversing of tables and chains - Страница 85
- General - Страница 86
- Mangle table - Страница 89
- Nat table - Страница 90
- Raw table - Страница 91
- Filter table - Страница 92
- User specified chains - Страница 93
- What's next? - Страница 94
- Chapter 7. The state machine - Страница 95
- Introduction - Страница 96
- The conntrack entries - Страница 97
- User-land states - Страница 99
- TCP connections - Страница 100
- UDP connections - Страница 102
- ICMP connections - Страница 103
- Default connections - Страница 105
- Untracked connections and the raw table - Страница 106
- Complex protocols and connection tracking - Страница 107
- What's next? - Страница 109
- Chapter 8. Saving and restoring large rule-sets - Страница 110
- Speed considerations - Страница 111
- Drawbacks with restore - Страница 112
- iptables-save - Страница 113
- iptables-restore - Страница 115
- What's next? - Страница 116
- Chapter 9. How a rule is built - Страница 117
- Basics of the iptables command - Страница 118
- Tables - Страница 119
- Commands - Страница 120
- What's next? - Страница 122
- Chapter 10. Iptables matches - Страница 123
- Generic matches - Страница 124
- Implicit matches - Страница 125
- TCP matches - Страница 126
- UDP matches - Страница 127
- ICMP matches - Страница 128
- SCTP matches - Страница 129
- Explicit matches - Страница 131
- Addrtype match - Страница 132
- AH/ESP match - Страница 133
- Comment match - Страница 134
- Connmark match - Страница 135
- Conntrack match - Страница 136
- Dscp match - Страница 137
- Ecn match - Страница 138
- Hashlimit match - Страница 139
- Helper match - Страница 140
- IP range match - Страница 141
- Length match - Страница 142
- Limit match - Страница 143
- Mac match - Страница 144
- Mark match - Страница 145
- Multiport match - Страница 146
- Owner match - Страница 147
- Packet type match - Страница 148
- Realm match - Страница 149
- Recent match - Страница 150
- State match - Страница 152
- Tcpmss match - Страница 153
- Tos match - Страница 154
- Ttl match - Страница 155
- Unclean match - Страница 156
- What's next? - Страница 157
- Chapter 11. Iptables targets and jumps - Страница 158
- ACCEPT target - Страница 159
- CLASSIFY target - Страница 160
- CLUSTERIP target - Страница 161
- CONNMARK target - Страница 163
- CONNSECMARK target - Страница 164
- DNAT target - Страница 165
- DROP target - Страница 168
- DSCP target - Страница 169
- ECN target - Страница 170
- LOG target options - Страница 171
- MARK target - Страница 172
- MASQUERADE target - Страница 173
- MIRROR target - Страница 174
- NETMAP target - Страница 175
- NFQUEUE target - Страница 176
- NOTRACK target - Страница 177
- QUEUE target - Страница 178
- REDIRECT target - Страница 179
- REJECT target - Страница 180
- RETURN target - Страница 181
- SAME target - Страница 182
- SECMARK target - Страница 183
- SNAT target - Страница 184
- TCPMSS target - Страница 185
- TOS target - Страница 186
- TTL target - Страница 187
- ULOG target - Страница 188
- What's next? - Страница 189
- Chapter 12. Debugging your scripts - Страница 190
- Debugging, a necessity - Страница 191
- Bash debugging tips - Страница 192
- System tools used for debugging - Страница 194
- Iptables debugging - Страница 195
- Other debugging tools - Страница 196
- Nmap - Страница 197
- Nessus - Страница 198
- What's next? - Страница 199
- Chapter 13. rc.firewall file - Страница 200
- example rc.firewall - Страница 201
- explanation of rc.firewall - Страница 202
- Initial loading of extra modules - Страница 203
- proc set up - Страница 205
- Displacement of rules to different chains - Страница 206
- Setting up default policies - Страница 208
- Setting up user specified chains in the filter table - Страница 209
- INPUT chain - Страница 212
- FORWARD chain - Страница 214
- OUTPUT chain - Страница 215
- PREROUTING chain of the nat table - Страница 216
- Starting SNAT and the POSTROUTING chain - Страница 217
- What's next? - Страница 218
- Chapter 14. Example scripts - Страница 219
- rc.firewall.txt script structure - Страница 220
- The structure - Страница 221
- rc.firewall.txt - Страница 224
- rc.DMZ.firewall.txt - Страница 225
- rc.DHCP.firewall.txt - Страница 226
- rc.UTIN.firewall.txt - Страница 228
- rc.test-iptables.txt - Страница 229
- rc.flush-iptables.txt - Страница 230
- Limit-match.txt - Страница 231
- Pid-owner.txt - Страница 232
- Recent-match.txt - Страница 233
- Sid-owner.txt - Страница 234
- Ttl-inc.txt - Страница 235
- Iptables-save ruleset - Страница 236
- What's next? - Страница 237
- Chapter 15. Graphical User Interfaces for Iptables/netfilter - Страница 238
- fwbuilder - Страница 239
- Turtle Firewall Project - Страница 240
- Integrated Secure Communications System - Страница 241
- IPMenu - Страница 242
- Easy Firewall Generator - Страница 243
- What's next? - Страница 244
- Chapter 16. Commercial products based on Linux, iptables and netfilter - Страница 245
- Ingate Firewall 1200 - Страница 246
- What's next? - Страница 247
- Appendix A. Detailed explanations of special commands - Страница 248
- Listing your active rule-set - Страница 249
- Updating and flushing your tables - Страница 250
- Appendix B. Common problems and questions - Страница 251
- Problems loading modules - Страница 252
- State NEW packets but no SYN bit set - Страница 253
- SYN/ACK and NEW packets - Страница 254
- Internet Service Providers who use assigned IP addresses - Страница 255
- Letting DHCP requests through iptables - Страница 256
- mIRC DCC problems - Страница 257
- Appendix C. ICMP types - Страница 258
- Appendix D. TCP options - Страница 259
- Appendix E. Other resources and links - Страница 260
- Appendix F. Acknowledgments - Страница 264
- Appendix G. History - Страница 265
- Appendix H. GNU Free Documentation License - Страница 267
- 0. PREAMBLE - Страница 268
- 1. APPLICABILITY AND DEFINITIONS - Страница 269
- 2. VERBATIM COPYING - Страница 270
- 3. COPYING IN QUANTITY - Страница 271
- 4. MODIFICATIONS - Страница 272
- 5. COMBINING DOCUMENTS - Страница 274
- 6. COLLECTIONS OF DOCUMENTS - Страница 275
- 7. AGGREGATION WITH INDEPENDENT WORKS - Страница 276
- 8. TRANSLATION - Страница 277
- 9. TERMINATION - Страница 278
- 10. FUTURE REVISIONS OF THIS LICENSE - Страница 279
- How to use this License for your documents - Страница 280
- Appendix I. GNU General Public License - Страница 281
- 0. Preamble - Страница 282
- 1. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION - Страница 283
- 2. How to Apply These Terms to Your New Programs - Страница 286
- Appendix J. Example scripts code-base - Страница 287
- Example rc.firewall script - Страница 288
- Example rc.DMZ.firewall script - Страница 291
- Example rc.UTIN.firewall script - Страница 294
- Example rc.DHCP.firewall script - Страница 297
- Example rc.flush-iptables script - Страница 300
- Example rc.test-iptables script - Страница 301
- Index - Страница 302
- A - Страница 306
- B - Страница 307
- C - Страница 308
- D - Страница 312
- E - Страница 315
- F - Страница 318
- G - Страница 319
- H - Страница 320
- I - Страница 321
- J - Страница 325
- K - Страница 326
- L - Страница 327
- M - Страница 328
- N - Страница 331
- O - Страница 332
- P - Страница 333
- Q - Страница 335
- R - Страница 336
- S - Страница 339
- T - Страница 347
- U - Страница 352
- V - Страница 354
- W - Страница 355
- X - Страница 356
ULOG target
The ULOG target is used to provide user-space logging of matching packets. If a packet is matched and the ULOG target is set, the packet information is multicasted together with the whole packet through a netlink socket. One or more user-space processes may then subscribe to various multicast groups and receive the packet. This is in other words a more complete and more sophisticated logging facility that is only used by iptables and Netfilter so far, and it contains much better facilities for logging packets. This target enables us to log information to MySQL databases, and other databases, making it much simpler to search for specific packets, and to group log entries. You can find the ULOGD user-land applications at the ULOGD project page.
Table 11-21. ULOG target options
Option | --ulog-nlgroup |
Example | iptables -A INPUT -p TCP --dport 22 -j ULOG --ulog-nlgroup 2 |
Explanation | The --ulog-nlgroup option tells the ULOG target which netlink group to send the packet to. There are 32 netlink groups, which are simply specified as 1-32. If we would like to reach netlink group 5, we would simply write --ulog-nlgroup 5. The default netlink group used is 1. |
Option | --ulog-prefix |
Example | iptables -A INPUT -p TCP --dport 22 -j ULOG --ulog-prefix "SSH connection attempt: " |
Explanation | The --ulog-prefix option works just the same as the prefix value for the standard LOG target. This option prefixes all log entries with a user-specified log prefix. It can be 32 characters long, and is definitely most useful to distinguish different log-messages and where they came from. |
Option | --ulog-cprange |
Example | iptables -A INPUT -p TCP --dport 22 -j ULOG --ulog-cprange 100 |
Explanation | The --ulog-cprange option tells the ULOG target how many bytes of the packet to send to the user-space daemon of ULOG. If we specify 100 as above, we would copy 100 bytes of the whole packet to user-space, which would include the whole header hopefully, plus some leading data within the actual packet. If we specify 0, the whole packet will be copied to user-space, regardless of the packets size. The default value is 0, so the whole packet will be copied to user-space. |
Option | --ulog-qthreshold |
Example | iptables -A INPUT -p TCP --dport 22 -j ULOG --ulog-qthreshold 10 |
Explanation | The --ulog-qthreshold option tells the ULOG target how many packets to queue inside the kernel before actually sending the data to user-space. For example, if we set the threshold to 10 as above, the kernel would first accumulate 10 packets inside the kernel, and then transmit it outside to the user-space as one single netlink multi part message. The default value here is 1 because of backward compatibility, the user-space daemon did not know how to handle multi-part messages previously. |
Note Works under Linux kernel 2.3, 2.4, 2.5 and 2.6.
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