jail.conf

# cat /etc/jail.conf
exec.start = "/bin/sh /etc/rc";
exec.stop  = "/bin/sh /etc/rc.shutdown";
exec.clean;                     
allow.raw_sockets;             
allow.mount.tmpfs;
mount.devfs;                         
 
                                                        
base {                                                               
    $id     = "10";                                              
    $ipaddr = "172.16.150.${id}";
    $mask   = "255.255.255.0";                            
    $gw     = "172.16.150.1";                                                     
    vnet;                                               
    vnet.interface = "epair${id}b";       
 
    exec.prestart   = "ifconfig epair${id} create up";           
    exec.prestart  += "ifconfig epair${id}a up descr vnet-${name}";
    exec.prestart  += "ifconfig bridge150 addm epair${id}a up";
                                    
    exec.start      = "/sbin/ifconfig lo0 127.0.0.1 up";
    exec.start     += "/sbin/ifconfig epair${id}b ${ipaddr} netmask ${mask} up";
    exec.start     += "/sbin/route add default ${gw}";
    exec.start     += "/bin/sh /etc/rc";
        
    exec.poststop  += "ifconfig epair${id}a destroy";
                                
    host.hostname = "${name}.loc";
    path = "/usr/local/jailz/${name}";
    persist;                         
}
                                                        
git0 {                                                               
    $id     = "11";                                              
    $ipaddr = "172.16.150.${id}";
    $mask   = "255.255.255.0";                            
    $gw     = "172.16.150.1";                                                     
    vnet;                                               
    vnet.interface = "epair${id}b";       

    exec.prestart   = "ifconfig epair${id} create up";
    exec.prestart  += "ifconfig epair${id}a up descr vnet-${name}";
    exec.prestart  += "ifconfig bridge150 addm epair${id}a up";

    exec.start      = "/sbin/ifconfig lo0 127.0.0.1 up";
    exec.start     += "/sbin/ifconfig epair${id}b ${ipaddr} netmask ${mask} up";
    exec.start     += "/sbin/route add default ${gw}";
    exec.start     += "/bin/sh /etc/rc";

    exec.poststop  += "ifconfig epair${id}a destroy";

    host.hostname = "${name}.loc";
    path = "/usr/local/jailz/${name}";
    persist;
}

rc.conf

cloned_interfaces="bridge150"
ifconfig_bridge150="inet 192.168.150.1 netmask 255.255.255.0"