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A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Use sudo iptables -L -v -n --line-numbers to see the IPv4 rules in the default filter table, including counters and one-based rule numbers. To remove one rule, list its chain, then run sudo iptables -D CHAIN NUMBER—for example, sudo iptables -D INPUT 3. Re-list the chain immediately afterward because the remaining rules move up. For IPv6, use the identical forms with ip6tables.
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What iptables is changing
iptables and ip6tables are administration tools for packet filtering and network address translation on Linux. A rule belongs to a table and a chain. The default table is filter; common built-in chains in that table include INPUT (traffic arriving for the host), OUTPUT (traffic generated by the host), and FORWARD (traffic routed through the host). A command that omits -t therefore reads or edits filter, not every table on the system.
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The current iptables 1.8.13 manual documents the forms used here. The command edits the active in-memory ruleset. Whether those changes survive a reboot depends on the Linux distribution’s firewall or persistence mechanism; there is no single persistence command defined by the iptables manual.
Before you edit: access, scope, and a rollback record
Get administrative access
Listing may work as an unprivileged user on some systems, but editing the ruleset normally requires root privileges. Prefix commands with sudo, or open a root shell if that is how your host is administered.
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Confirm the address family
iptables operates on IPv4 rules. IPv6 rules are a separate ruleset viewed and edited with ip6tables. Removing an IPv4 rule does not remove an equivalent IPv6 rule.
Record the current rule specifications
Before deleting anything, save a command-like representation of the relevant table:
sudo iptables -S
sudo iptables -t nat -S-S prints rules in rule-specification form. It is useful as an audit record and provides the exact options needed for a specification-based deletion. If you are working with IPv6, substitute ip6tables.
Be certain you have an alternate session
A mistaken removal from an INPUT chain can affect remote administration. Make changes from a console or keep a second management session available so that a connectivity mistake can be corrected.
Command reference
| Purpose | Command | What it shows or changes |
|---|---|---|
| List the default filter table | sudo iptables -L -v -n --line-numbers |
All chains in filter, with counters, numeric addresses and ports, and one-based positions. |
| List one filter chain | sudo iptables -L INPUT -v -n --line-numbers |
Only the INPUT chain, with details and rule numbers. |
| Show rule specifications | sudo iptables -S |
Rules as command-like specifications, suitable for recording or reusing. |
| List a non-default table | sudo iptables -t nat -L -v -n --line-numbers |
Rules in the nat table; replace nat with another relevant table. |
| Delete by position | sudo iptables -D INPUT 3 |
Deletes rule 3 from INPUT in the default filter table. |
| Delete by position in another table | sudo iptables -t nat -D PREROUTING 2 |
Deletes rule 2 from PREROUTING in nat. |
| Delete by specification | sudo iptables -D INPUT -s 203.0.113.10 -p tcp --dport 22 -j DROP |
Removes the first rule whose complete specification matches. |
List the rules you actually need
List every chain in the filter table
sudo iptables -L -v -n --line-numbers-Llists rules.-vadds verbose fields, including packet and byte counters and other details.-nkeeps addresses and ports numeric instead of performing reverse-DNS and service-name lookups. This is usually faster and avoids output changing because of name resolution.--line-numbersprints each rule’s one-based position in its chain.
Read the chain heading before interpreting a number. Rule 3 in INPUT is unrelated to rule 3 in OUTPUT or in another table.
Inspect a single chain
Once you know where the traffic is evaluated, narrow the output:
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sudo iptables -L INPUT -v -n --line-numbers
sudo iptables -L OUTPUT -v -n --line-numbers
sudo iptables -L FORWARD -v -n --line-numbersUse the chain-specific view when deciding which numbered entry to remove. It makes the position unambiguous and keeps unrelated chains out of the inspection.
Inspect non-filter tables
Use -t for a table other than filter. The command must specify the same table when you later delete a rule.
sudo iptables -t filter -L -v -n --line-numbers
sudo iptables -t nat -L -v -n --line-numbers
sudo iptables -t mangle -L -v -n --line-numbers
sudo iptables -t raw -L -v -n --line-numbersOnly query tables that exist and are relevant on the host. NAT rules, for example, are not shown by an unqualified -L because that command reads filter by default.
Capture an exact, reusable form
sudo iptables -S
sudo iptables -S INPUT
sudo iptables -t nat -S PREROUTINGThe -S output identifies the chain and expresses each rule with its matches and target. Copy the current specification rather than reconstructing it from memory before using the specification-deletion form.
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Number-based deletion is the clearest choice when you have inspected the chain and want to remove exactly one entry at its current position.
- Choose the table and chain. Decide whether the rule is in
filter,nat,mangle, orraw, and note the chain name. - List that chain with numbers.
sudo iptables -L INPUT -v -n --line-numbers - Match the rule’s position and behavior. Check its source or destination, protocol, ports, interface, target, and counters. Do not rely on the number alone if another administrator may have changed the chain.
- Delete the numbered entry.
sudo iptables -D INPUT 3 - Use the same table option for non-filter rules.
sudo iptables -t nat -D PREROUTING 2 - Verify the result.
sudo iptables -L INPUT -v -n --line-numbers
Rule positions start at 1, not 0. After a deletion, every later rule shifts toward the top of the chain. Re-list the chain before removing another number; otherwise a previously observed number can point to a different rule.
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Delete by the complete rule specification
Specification-based deletion avoids counting a volatile position. Replace the original add operation’s -A with -D, keep the same chain, matches, options, and target, and include the same table selection.
sudo iptables -D INPUT -s 203.0.113.10 -p tcp --dport 22 -j DROPThis example removes the first INPUT rule that matches the source address, TCP protocol, destination port 22, and DROP target. If identical rules occur more than once, the first matching entry is deleted.
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Copy the live form instead of guessing
- Print the current specifications:
sudo iptables -S INPUT - Find the exact rule, including its target and every match option.
- Run the copied rule with
-Din place of-A. - List the chain again with counters and line numbers to confirm which entry disappeared.
The Netfilter HOWTO specifies that deletion syntax must have exactly the same options as the corresponding add, insert, or replace command. Differences in aliases, implicit modules, address notation, or option order can cause an assumed specification not to match. The live -S output is therefore the safest source for this method.
Number deletion versus specification deletion
| Criterion | Delete by number | Delete by specification |
|---|---|---|
| Precision for a one-time edit | High after an immediately preceding inspection; targets one current position. | High when the copied specification is exact; removes the first matching rule. |
| Effect of other edits | High susceptibility: positions change whenever an earlier rule is inserted or removed. | Less dependent on position, but duplicate rules still make the first match the one removed. |
| Auditability | The numbered list shows exactly which position was selected at the time. | The command records the match and target that were intended for removal. |
| Ease of preparation | List the chain and count; no long command needs to be reconstructed. | Copy from -S; hand-typing a near-match can fail. |
| Blast radius | One rule. | One matching rule, specifically the first duplicate if duplicates exist. |
For a single interactive cleanup, numbered deletion followed by verification is usually easiest. For a documented change or a script that must identify the rule by its behavior, copy the specification and use -D.
Do not confuse a single deletion with a flush
Flush a chain or table with -F
-F removes every rule from the selected chain. If no chain is named, it flushes every chain in the selected table.
sudo iptables -F INPUT
sudo iptables -t nat -FThe first command empties only INPUT in filter. The second empties all chains in nat. A flush is equivalent to deleting the rules one by one, but its blast radius is much larger than either single-rule form. Use it only when removing the complete selected set is intentional and you have a recovery plan.
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Remove a user-defined chain with -X
-X removes a user-defined chain only after it is empty and no other rules refer to it:
sudo iptables -X CUSTOM_CHAINBuilt-in chains such as INPUT, OUTPUT, and FORWARD are not ordinary user-defined chains and cannot be removed this way. Emptying a built-in chain with -F is a different operation from deleting the chain itself.
List and delete IPv6 rules
Use ip6tables for the IPv6 ruleset. Its list and delete forms parallel iptables:
sudo ip6tables -L -v -n --line-numbers
sudo ip6tables -L INPUT -v -n --line-numbers
sudo ip6tables -S
sudo ip6tables -D INPUT 3Apply the same discipline: identify the table and chain, inspect the one-based position or copy the exact specification, delete only the intended rule, and re-list the chain. If the rule is in a non-default table, add the table selector to both commands, for example:
sudo ip6tables -t nat -L -v -n --line-numbers
sudo ip6tables -t nat -D PREROUTING 2A repeatable, low-risk operating sequence
- Determine the family. Decide whether the traffic is IPv4 (
iptables) or IPv6 (ip6tables). - Determine the table. Start with
filterunless the behavior is clearly NAT, packet mangling, or raw-table processing; explicitly inspect the relevant table with-t. - Record the state. Run
-Sfor the table and chain you will edit and retain the output in your change record. - Inspect the chain. Use
-L CHAIN -v -n --line-numbersand identify the target, matches, counters, and current position. - Select the narrowest operation. Use
-D CHAIN NUMBERfor a one-time positional removal or an exact specification with-Dwhen the rule’s behavior is the identifier. Do not use-Funless the entire chain or table must be emptied. - Re-list immediately. Confirm the intended rule is gone and note the new positions of rules that remain.
- Exercise the affected traffic path. Test the specific connection, forwarding path, or translation that motivated the change rather than assuming a successful command means the policy is correct.
- Handle persistence separately. If the change must survive reboot, update the host’s distribution-specific persistence mechanism after validating the live ruleset.
Common mistakes and their fixes
The rule is not in the output
- You may be looking at
filterwhile the rule is innat,mangle, orraw. Repeat the list command with the appropriate-t. - You may be checking IPv4 while the traffic uses IPv6. Run the corresponding
ip6tablescommand. - You may have inspected the wrong chain. List
INPUT,OUTPUT, orFORWARDseparately, or the relevant user-defined chain.
A numbered deletion removed the wrong rule
Positions are one-based and shift after every earlier deletion or insertion. Re-list the exact chain immediately before each deletion. If concurrent changes make positions unreliable, copy the live rule from -S and delete by specification instead.
Specification deletion reports no match
Do not simplify the command. Compare it with the current -S output character for character, including source or destination notation, protocol, ports, interfaces, match modules, and target. Include the table selector if the original rule was not in filter.
The command succeeds but traffic still behaves the same
Re-list the chain and inspect counters. You may have deleted a rule in a path that is not handling the traffic, left a duplicate rule, or edited one address family while the connection uses the other. Check the relevant table and chain rather than repeating the same deletion.
Remote access stops after the edit
Use the alternate console or management session prepared before the change. Restore the intended rule using the same table, chain, and specification, then verify the chain and test access again. A numbered deletion can be reversed only after you know the original rule; this is why recording -S first matters.
The change disappears after reboot
The iptables command manages the active ruleset; its manual does not define one universal save-and-restore service. Configure the persistence mechanism used by the particular Linux distribution or firewall manager, and verify the restored rules after a reboot or service restart.
Worked examples
Remove rule 3 from IPv4 INPUT
sudo iptables -S INPUT
sudo iptables -L INPUT -v -n --line-numbers
sudo iptables -D INPUT 3
sudo iptables -L INPUT -v -n --line-numbersThe first command records specifications, the second identifies the current numbered entry, the third removes only position 3, and the last confirms the result. If another rule was inserted between inspection and deletion, stop and inspect again instead of assuming that position 3 is unchanged.
Remove a specific SSH-source drop
sudo iptables -S INPUT
sudo iptables -D INPUT -s 203.0.113.10 -p tcp --dport 22 -j DROP
sudo iptables -L INPUT -v -n --line-numbersThis targets the first exact match for the source address, TCP destination port 22, and DROP target. If the rule shown by -S contains additional match options, include all of them in the deletion command.
Remove one NAT prerouting rule
sudo iptables -t nat -L PREROUTING -v -n --line-numbers
sudo iptables -t nat -D PREROUTING 2
sudo iptables -t nat -L PREROUTING -v -n --line-numbersThe -t nat option appears on every command so that listing and deletion address the same table.
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What the output tells you
A numbered listing gives you more than a deletion index. The verbose columns include packet and byte counters, which help show whether a rule has handled traffic. Numeric mode keeps addresses and ports literal, making it easier to compare output with logs and with the specification printed by -S. The target at the end of each rule—such as ACCEPT, DROP, or a jump to another chain—describes the action that will no longer occur after deletion.
Read those fields together. A rule with a familiar number but a different chain, table, target, or address is not the rule you intended to remove.
Quick Recap
Key points to retain
- Unqualified commands operate on the
filtertable; use-tfornat,mangle, orraw. --line-numbersreports one-based positions, and positions change after deletions.-D CHAIN NUMBERremoves one current entry; specification deletion removes the first exact match.-Fflushes a chain or an entire table and is not a substitute for removing one rule.iptablesandip6tablesmaintain separate IPv4 and IPv6 rulesets.- Always record with
-S, verify by listing again, test the intended path, and configure persistence separately when required.
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