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clearing_iptables

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clearing_iptables [2023/03/08 12:21] – created rs232clearing_iptables [2024/10/31 21:09] (current) – hogwild
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-===== Clearing iptables custom commands prior to re-applying new ones =====+===== Clearing iptables custom commands prior to applying new ones =====
  
-Assuming the user want so use some custom iptables commands in e.g. script/firewall (but this applies to any re-occurring script like wan-up/etc) you can remove what previously added iptables directive with a simple approach. +As an example, let's say that you wanted to use some custom iptables commands in a script, such as the firewall script. (Actually, the following principles would apply to any recurring script, such as "WAN Up").
  
 + \\ You can remove previously-added iptables directives using a simple approach:
 +
 + \\
  
 ''nvram get script_fire | grep -E '^iptables*' | sed 's/-A\|-I/-D/' | while read line; do exec ${line} &>/dev/null; done'' ''nvram get script_fire | grep -E '^iptables*' | sed 's/-A\|-I/-D/' | while read line; do exec ${line} &>/dev/null; done''
  
-This command here below will check what iptables -A (append) or -I (insert) have been used in the current Script/Firewall text area and force a run of the same command replacing any **-A** or **-I** with a **-D** (Delete) essentially removing any user added iptables directive. To be noted that for advanced iptables commands a user might have created custom tables, this is usually achieved via "-N" (new). You can apply the same principle as per above looking for **-N**. Do remember that: + \\ 
-  * you need to un-reference the custom table from the built in one first (as per approach above) + 
-  * a table needs to be empties with **-F** (Flush) first e.g. **iptables -F $TABLE_NAME** +The commands below will check what iptables **-A** (append) or **-I** (insert) directives have been issued previously in the current Script/Firewall text. They will then force a run of the same command, replacing any instance of **-A** or **-I** with a **-D** (Delete) command. In essence, this will reverse/remove any previous user-added iptables directives. 
-  * only at this point you will be allowed to remove the table with a **iptables -X $TABLE_NAME**. + 
 +You might have created custom tables in which to use advanced iptables commands. This is usually performed using the "**-N**" (new) command. The same principles described above will also apply to previously-issued directives which used the **-N command**. 
 + 
 + \\ Here are a few rules to remember when using these commands: 
 + 
 + \\ 
 + 
 +  * First, you need to dereference the custom table from the built-in one, \\ using the above method. 
 +  * A table must then be emptied with the **-F** (Flush) switch/parameter \\ (for example: "**iptables -F $TABLE_NAME") **. 
 +  * Only then will you be allowed to remove the table by using the command: \\ "**iptables -X $TABLE_NAME"**. 
 + 
 + \\ 
  
clearing_iptables.1678278100.txt.gz · Last modified: by rs232

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