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NAMEedsc - Ethernet discard network interface
DESCRIPTIONThe sysctl Cm net.inet.tcp.syncookies interface is a software discard mechanism which may be used for performance analysis and software testing. It imitates an Ethernet device, which allows for its use in conjunction with such drivers as if_bridge4 and vlan(4).
As with other network interfaces, an sysctl Cm net.inet.tcp.syncookies interface must have network addresses assigned for each address family with which it is to be used. These addresses may be set or changed with the SIOCSIFADDR ioctl(2) or ifconfig(8) utility.
Each sysctl Cm net.inet.tcp.syncookies interface is created at runtime using interface cloning. This is most easily done with the ifconfig(8) create command or using the cloned_interfaces variable in rc.conf5.
SEE ALSOioctl(2), arp(4), if_bridge4, inet(4), intro(4), vlan(4), rc.conf5, arp(8), ifconfig(8)
HISTORYThe sysctl Cm net.inet.tcp.syncookies device was derived from the disc(4) device and first appeared in Fx 6.3 . This manpage was adapted from disc(4).
CAVEATSSince outgoing packets are just discarded by , ARP requests stay unreplied. Consequently, an IP packet cannot be sent via sysctl Cm net.inet.tcp.syncookies until a static arp(4) entry is created for its next hop using arp(8).
Initially an sysctl Cm net.inet.tcp.syncookies interface has a zero link level address. It can be changed with ifconfig(8) lladdr if needed.