Conntrack

VyOS can be configured to track connections using the connection tracking subsystem. Connection tracking becomes operational once either stateful firewall or NAT is configured.

Configure

set system conntrack table-size <1-50000000>

default: 262144

The connection tracking table contains one entry for each connection being tracked by the system.

set system conntrack expect-table-size <1-50000000>

default: 2048

The connection tracking expect table contains one entry for each expected connection related to an existing connection. These are generally used by “connection tracking helper” modules such as FTP. The default size of the expect table is 2048 entries.

set system conntrack hash-size <1-50000000>

default: 32768

Set the size of the hash table. The connection tracking hash table makes searching the connection tracking table faster. The hash table uses “buckets” to record entries in the connection tracking table.

set system conntrack modules ftp

set system conntrack modules h323

set system conntrack modules nfs

set system conntrack modules pptp

set system conntrack modules sip

set system conntrack modules sqlnet

set system conntrack modules tftp

Configure the connection tracking protocol helper modules. All modules are enable by default.

Use delete system conntrack modules to deactive all modules.

Or, for example ftp, delete system conntrack modules ftp.

set system conntrack tcp half-open-connections <1-21474836>

default: 512

Set the maximum number of TCP half-open connections.

set system conntrack tcp loose <enable | disable>

default: enable

Policy to track previously established connections.

set system conntrack tcp max-retrans <1-2147483647>

default: 3

Set the number of TCP maximum retransmit attempts.

Contrack Timeouts

You can define custom timeout values to apply to a specific subset of connections, based on a packet and flow selector. To do this, you need to create a rule defining the packet and flow selector.

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> description <test>

Set a rule description.

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> destination address <ip-address>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> source address <ip-address>

Set a destination and/or source address. Accepted input for ipv4:

set system conntrack timeout custom ipv4 rule <1-999999> [source | destination] address
Possible completions:
   <x.x.x.x>            IPv4 address to match
   <x.x.x.x/x>          IPv4 prefix to match
   <x.x.x.x>-<x.x.x.x>  IPv4 address range to match
   !<x.x.x.x>           Match everything except the specified address
   !<x.x.x.x/x>         Match everything except the specified prefix
   !<x.x.x.x>-<x.x.x.x> Match everything except the specified range

set system conntrack timeout custom ipv6 rule <1-999999> [source | destination] address
Possible completions:
   <h:h:h:h:h:h:h:h>    IP address to match
   <h:h:h:h:h:h:h:h/x>  Subnet to match
   <h:h:h:h:h:h:h:h>-<h:h:h:h:h:h:h:h>
                        IP range to match
   !<h:h:h:h:h:h:h:h>   Match everything except the specified address
   !<h:h:h:h:h:h:h:h/x> Match everything except the specified prefix
   !<h:h:h:h:h:h:h:h>-<h:h:h:h:h:h:h:h>
                        Match everything except the specified range

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> destination port <value>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> source port <value>

Set a destination and/or source port. Accepted input:

<port name>    Named port (any name in /etc/services, e.g., http)
<1-65535>      Numbered port
<start>-<end>  Numbered port range (e.g., 1001-1005)

Multiple destination ports can be specified as a comma-separated list. The whole list can also be “negated” using ‘!’. For example: !22,telnet,http,123,1001-1005`

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp close <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp close-wait <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp established <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp fin-wait <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp last-ack <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp syn-recv <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp syn-sent <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol tcp time-wait <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol udp replied <1-21474836>

set system conntrack timeout custom [ipv4 | ipv6] rule <1-999999> protocol udp unreplied <1-21474836>

Set the timeout in seconds for a protocol or state in a custom rule.

Conntrack ignore rules

Note

Important note about conntrack ignore rules: Starting from vyos-1.5-rolling-202406120020, ignore rules can be defined in set firewall [ipv4 | ipv6] prerouting raw .... It’s expected that in the future the conntrack ignore rules will be removed.

Customized ignore rules, based on a packet and flow selector.

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> description <text>

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> destination address <ip-address>

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> destination port <port>

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> inbound-interface <interface>

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> protocol <protocol>

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> source address <ip-address>

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> source port <port>

set system conntrack ignore [ipv4 | ipv6] rule <1-999999> tcp flags [not] <text>

Allowed values fpr TCP flags: ack, cwr, ecn, fin, psh, rst, syn and urg. Multiple values are supported, and for inverted selection use not, as shown in the example.

Conntrack log

set system conntrack log event destroy

set system conntrack log event new

set system conntrack log event update

Log the connection tracking events per type.

set system conntrack log event destroy icmp

set system conntrack log event destroy other

set system conntrack log event destroy tcp

set system conntrack log event destroy udp

set system conntrack log event new icmp

set system conntrack log event new other

set system conntrack log event new tcp

set system conntrack log event new udp

set system conntrack log event update icmp

set system conntrack log event update other

set system conntrack log event update tcp

set system conntrack log event update udp

Log the connection tracking events per protocol.

set system conntrack log timestamp

Turn on flow-based timestamp extension.

set system conntrack log queue-size <100-999999>

Manage internal queue size, default size is 4096 events.

set system conntrack log log-level <info | debug>

Manage log level