| Match by how many bytes or packets a connection (or one of the two |
| flows constituting the connection) has transferred so far, or by |
| average bytes per packet. |
| .PP |
| The counters are 64-bit and are thus not expected to overflow ;) |
| .PP |
| The primary use is to detect long-lived downloads and mark them to be |
| scheduled using a lower priority band in traffic control. |
| .PP |
| The transferred bytes per connection can also be viewed through |
| `conntrack -L` and accessed via ctnetlink. |
| .PP |
| NOTE that for connections which have no accounting information, the match will |
| always return false. The "net.netfilter.nf_conntrack_acct" sysctl flag controls |
| whether \fBnew\fP connections will be byte/packet counted. Existing connection |
| flows will not be gaining/losing a/the accounting structure when be sysctl flag |
| is flipped. |
| .TP |
| [\fB!\fP] \fB\-\-connbytes\fP \fIfrom\fP[\fB:\fP\fIto\fP] |
| match packets from a connection whose packets/bytes/average packet |
| size is more than FROM and less than TO bytes/packets. if TO is |
| omitted only FROM check is done. "!" is used to match packets not |
| falling in the range. |
| .TP |
| \fB\-\-connbytes\-dir\fP {\fBoriginal\fP|\fBreply\fP|\fBboth\fP} |
| which packets to consider |
| .TP |
| \fB\-\-connbytes\-mode\fP {\fBpackets\fP|\fBbytes\fP|\fBavgpkt\fP} |
| whether to check the amount of packets, number of bytes transferred or |
| the average size (in bytes) of all packets received so far. Note that |
| when "both" is used together with "avgpkt", and data is going (mainly) |
| only in one direction (for example HTTP), the average packet size will |
| be about half of the actual data packets. |
| .TP |
| Example: |
| iptables .. \-m connbytes \-\-connbytes 10000:100000 \-\-connbytes\-dir both \-\-connbytes\-mode bytes ... |