Clever Geek Handbook

Using nftables in Red Hat Enterprise Linux 8

The article was prepared on the eve of the start of the course "Linux Administrator"







Red Hat Enterprise Linux 8 nftables. , nftables. DevOps-. , , nftables — iptables.



, nftables – userland-, nft . netfilter. nft.



, . .



: , .




, nftables -? , .



# nft list ruleset


… . , . ?



nftables , iptables. . , iptables, , , .





nftables . : ip, ip6, inet, arp, bridge netdev. inet , ipv4 ipv6. .



: , iptables, . nftables – , , . , , , .

.



# nft add table inet my_table
# nft list ruleset
table inet my_table {
}


, , . .





– , .



, . , , , . filter, input, priority 0 , .



# nft add chain inet my_table my_filter_chain { type filter hook input priority 0 \; }


: () , shell .

. , iptables. jump goto . , , .



# nft add chain inet my_table my_utility_chain




, , , , . SSH.



# nft add rule inet my_table my_filter_chain tcp dport ssh accept


, inet, IPv4, IPv6.



add . insert, .



# nft insert rule inet my_table my_filter_chain tcp dport http accept


, , .



# nft list ruleset
table inet my_table {
    chain my_filter_chain {
    type filter hook input priority 0; policy accept;
    tcp dport http accept
    tcp dport ssh accept
    }
}


, http ssh, insert.



. .



  1. index, . add . insert, . 0.


# nft insert rule inet my_table my_filter_chain index 1 tcp dport nfs accept
# nft list ruleset
table inet my_table {
    chain my_filter_chain {
    type filter hook input priority 0; policy accept;
    tcp dport http accept
    tcp dport nfs accept
    tcp dport ssh accept
    }
}

# nft add rule inet my_table my_filter_chain index 0 tcp dport 1234 accept
# nft list ruleset
table inet my_table {
    chain my_filter_chain {
    type filter hook input priority 0; policy accept;
    tcp dport http accept
    tcp dport 1234 accept
    tcp dport nfs accept
    tcp dport ssh accept
    }
}


: index insert iptables -I . , , , nftables 0. -, . "nft insert rule … index 0" .


  1. handle, , . add. , insert. handle , –handle . 


# nft --handle list ruleset
table inet my_table { # handle 21
    chain my_filter_chain { # handle 1
    type filter hook input priority 0; policy accept;
    tcp dport http accept # handle 3
    tcp dport ssh accept # handle 2
    }
}
# nft add rule inet my_table my_filter_chain handle 3 tcp dport 1234 accept
# nft insert rule inet my_table my_filter_chain handle 2 tcp dport nfs accept
# nft --handle list ruleset
table inet my_table { # handle 21
    chain my_filter_chain { # handle 1
    type filter hook input priority 0; policy accept;
    tcp dport http accept # handle 3
    tcp dport 1234 accept # handle 8
    tcp dport nfs accept # handle 7
    tcp dport ssh accept # handle 2
    }
}


nftables handle , . , , .



handle , –echo –handle. CLI handle.



# nft --echo --handle add rule inet my_table my_filter_chain udp dport 3333 accept
add rule inet my_table my_filter_chain udp dport 3333 accept # handle 4


: nftables . handle.




handle add insert .



handle , .



# nft --handle list ruleset
table inet my_table { # handle 21
    chain my_filter_chain { # handle 1
    type filter hook input priority 0; policy accept;
    tcp dport http accept # handle 3
    tcp dport 1234 accept # handle 8
    tcp dport nfs accept # handle 7
    tcp dport ssh accept # handle 2
    }
}


handle .



# nft delete rule inet my_table my_filter_chain handle 8
# nft --handle list ruleset
table inet my_table { # handle 21
    chain my_filter_chain { # handle 1
    type filter hook input priority 0; policy accept;
    tcp dport http accept # handle 3
    tcp dport nfs accept # handle 7
    tcp dport ssh accept # handle 2
    }
}




. .



.



# nft list table inet my_table
table inet my_table {
    chain my_filter_chain {
        type filter hook input priority 0; policy accept;
        tcp dport http accept
        tcp dport nfs accept
        tcp dport ssh accept
    }
}


.



# nft list chain inet my_table my_other_chain
table inet my_table {
    chain my_other_chain {
        udp dport 12345 log prefix "UDP-12345"
    }
}




nftables . , , IP-, , .





inline-. , .



, 10.10.10.123 10.10.10.231.



# nft add rule inet my_table my_filter_chain ip saddr { 10.10.10.123, 10.10.10.231 } accept
# nft list ruleset
table inet my_table {
    chain my_filter_chain {
        type filter hook input priority 0; policy accept;
        tcp dport http accept
        tcp dport nfs accept
        tcp dport ssh accept
        ip saddr { 10.10.10.123, 10.10.10.231 } accept
    }


, , . , .



, .



# nft add rule inet my_table my_filter_chain tcp dport { http, nfs, ssh } accept


: iptables ipset. nftables , ipset .




Nftables . , . , : ipv4_addr, inet_service, ether_addr.



.



# nft add set inet my_table my_set { type ipv4_addr \; }
# nft list sets
table inet my_table {
    set my_set {
    type ipv4_addr
    }
}


@ . IP- .



# nft insert rule inet my_table my_filter_chain ip saddr @my_set drop
# nft list chain inet my_table my_filter_chain
table inet my_table {
    chain my_filter_chain {
    type filter hook input priority 0; policy accept;
    ip saddr @my_set drop
    tcp dport http accept
    tcp dport nfs accept
    tcp dport ssh accept
    ip saddr { 10.10.10.123, 10.10.10.231 } accept
    }
}


, , . .



# nft add element inet my_table my_set { 10.10.10.22, 10.10.10.33 }
# nft list set inet my_table my_set
table inet my_table {
    set my_set {
    type ipv4_addr
    elements = { 10.10.10.22, 10.10.10.33 }
    }
}


.



# nft add element inet my_table my_set { 10.20.20.0-10.20.20.255 }
Error: Set member cannot be range, missing interval flag on declaration
add element inet my_table my_set { 10.20.20.0-10.20.20.255 }


, . , , , .





. IP- . , .



# nft add set inet my_table my_range_set { type ipv4_addr \; flags interval \; }
# nft add element inet my_table my_range_set  { 10.20.20.0/24 }
# nft list set inet my_table my_range_set
table inet my_table {
    set my_range_set {
    type ipv4_addr
    flags interval
    elements = { 10.20.20.0/24 }
    }
}


: IP-. , 10.20.20.0-10.20.20.255 .




. , «.» .



IPv4-, IP- .



# nft add set inet my_table my_concat_set  { type ipv4_addr . inet_proto . inet_service \; }
# nft list set inet my_table my_concat_set
table inet my_table {
    set my_concat_set {
    type ipv4_addr . inet_proto . inet_service
    }
}


.



# nft add element inet my_table my_concat_set { 10.30.30.30 . tcp . telnet }


, (tcp, telnet) .



, .



# nft add rule inet my_table my_filter_chain ip saddr . meta l4proto . tcp dport @my_concat_set accept
# nft list chain inet my_table my_filter_chain
table inet my_table {
    chain my_filter_chain {
    ...
    ip saddr { 10.10.10.123, 10.10.10.231 } accept
    meta nfproto ipv4 ip saddr . meta l4proto . tcp dport @my_concat_set accept
    }
}


, inline-. , .



# nft add rule inet my_table my_filter_chain ip saddr . meta l4proto . udp dport { 10.30.30.30 . udp . bootps } accept


, nftables.



: nftables ipset, , hash:ip,port.


Verdict Map



Verdict map – nftables, , . , .



, , TCP UDP . verdict map, .



# nft add chain inet my_table my_tcp_chain
# nft add chain inet my_table my_udp_chain
# nft add rule inet my_table my_filter_chain meta l4proto vmap { tcp : jump my_tcp_chain, udp : jump my_udp_chain }
# nft list chain inet my_table my_filter_chain
table inet my_table {
    chain my_filter_chain {
    ...
    meta nfproto ipv4 ip saddr . meta l4proto . udp dport { 10.30.30.30 . udp . bootps } accept
    meta l4proto vmap { tcp : jump my_tcp_chain, udp : jump my_udp_chain }
    }
}


, verdict map.



# nft add map inet my_table my_vmap { type inet_proto : verdict \; }


. . , verdict map .



verdict map .



# nft add rule inet my_table my_filter_chain meta l4proto vmap @my_vmap




nftables – , . , .



# nft add table inet table_one
# nft add chain inet table_one my_chain
# nft add table inet table_two
# nft add chain inet table_two my_chain
# nft list ruleset
...
table inet table_one {
    chain my_chain {
    }
}
table inet table_two {
    chain my_chain {
    }
}


, , . iptables , .



. . , . table_one , table_two. . . , .





nftables . list nft , . nftables systemd.





# nft list ruleset > /root/nftables.conf




# nft -f /root/nftables.conf


, systemd . /etc/sysconfig/nftables.conf.



# systemctl enable nftables
# nft list ruleset > /etc/sysconfig/nftables.conf


: , RHEL-8, nftables /etc/nftables. iptables. /etc/sysconfig/nftables.conf, .




, nftables. nftables. , . nft . , , nftables.





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