1XTABLES-LEGACY(8)           System Manager's Manual          XTABLES-LEGACY(8)
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NAME

6       xtables-legacy  — iptables using old getsockopt/setsockopt-based kernel
7       api
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DESCRIPTION

11       xtables-legacy are the original versions of iptables that use old  get‐
12       sockopt/setsockopt-based  kernel  interface.  This kernel interface has
13       some limitations, therefore iptables can also be used  with  the  newer
14       nf_tables based API.  See xtables-nft(8) for information about the xta‐
15       bles-nft variants of iptables.
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USAGE

19       The xtables-legacy-multi binary can be linked to the traditional names:
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21            /sbin/iptables -> /sbin/iptables-legacy-multi
22            /sbin/ip6tables -> /sbin/ip6tables-legacy-multi
23            /sbin/iptables-save -> /sbin/ip6tables-legacy-multi
24            /sbin/iptables-restore -> /sbin/ip6tables-legacy-multi
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26       The iptables version  string  will  indicate  whether  the  legacy  API
27       (get/setsockopt) or the new nf_tables API is used:
28            iptables -V
29            iptables v1.7 (legacy)
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LIMITATIONS

33       When  inserting a rule using iptables -A or iptables -I, iptables first
34       needs to retrieve the current active ruleset, change it to include  the
35       new  rule,  and  then  commit  back the result.  This means that if two
36       instances of iptables are running  concurrently,  one  of  the  updates
37       might  be  lost.   This  can be worked around partially with the --wait
38       option.
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40       There is also no method to monitor changes to the ruleset, except peri‐
41       odically  calling iptables-legacy-save and checking for any differences
42       in output.
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44       xtables-monitor(8) will need the xtables-nft(8) versions  to  work,  it
45       cannot display changes made using the.  iptables-legacy tools.
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SEE ALSO

49       xtables-nft(8), xtables-translate(8)
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AUTHORS

53       Rusty  Russell  originally  wrote  iptables, in early consultation with
54       Michael Neuling.
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58                                   June 2018                 XTABLES-LEGACY(8)