T5472: nat redirect: allow redirection without defining redirected port

[nicolas-fort]

Change Summary

Allow redirection without defining redirected port

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5472

Component(s) name

nat

Proposed changes

Allow redirection without defining redirected port

How to test

vyos@redirect# run show config comm | grep nat
set nat destination rule 10 destination port '53'
set nat destination rule 10 inbound-interface 'eth4'
set nat destination rule 10 protocol 'udp'
set nat destination rule 10 translation redirect
set nat destination rule 20 destination port '21'
set nat destination rule 20 inbound-interface 'pppoe0'
set nat destination rule 20 protocol 'tcp'
set nat destination rule 20 translation redirect port '1021'
set nat destination rule 30 destination port '1001'
set nat destination rule 30 inbound-interface 'eth2'
set nat destination rule 30 protocol 'tcp'
set nat destination rule 30 translation address '198.51.100.100'
set nat destination rule 30 translation port '5555'
[edit]
vyos@redirect# sudo nft -s list table ip vyos_nat
table ip vyos_nat {
        chain PREROUTING {
                type nat hook prerouting priority dstnat; policy accept;
                counter jump VYOS_PRE_DNAT_HOOK
                iifname "eth4" udp dport 53 counter redirect comment "DST-NAT-10"
                iifname "pppoe0" tcp dport 21 counter redirect to :1021 comment "DST-NAT-20"
                iifname "eth2" tcp dport 1001 counter dnat to 198.51.100.100:5555 comment "DST-NAT-30"
        }

        chain POSTROUTING {
                type nat hook postrouting priority srcnat; policy accept;
                counter jump VYOS_PRE_SNAT_HOOK
        }

        chain VYOS_PRE_DNAT_HOOK {
                return
        }

        chain VYOS_PRE_SNAT_HOOK {
                return
        }
}
[edit]
vyos@redirect# 

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly