X-Git-Url: http://git.onelab.eu/?p=iproute2.git;a=blobdiff_plain;f=doc%2Factions%2Factions-general;fp=doc%2Factions%2Factions-general;h=0000000000000000000000000000000000000000;hp=bb2295d89d85d433a38e3dea9b1134417a21ca1a;hb=3331a68859fd71047bb1f309048960b48eab2d83;hpb=2bd4a72f2100be7ad7d9518cb1d49bb2a5b71994 diff --git a/doc/actions/actions-general b/doc/actions/actions-general deleted file mode 100644 index bb2295d..0000000 --- a/doc/actions/actions-general +++ /dev/null @@ -1,254 +0,0 @@ - -This documented is slightly dated but should give you idea of how things -work. - -What is it? ------------ - -An extension to the filtering/classification architecture of Linux Traffic -Control. -Up to 2.6.8 the only action that could be "attached" to a filter was policing. -i.e you could say something like: - ------ -tc filter add dev lo parent ffff: protocol ip prio 10 u32 match ip src \ -127.0.0.1/32 flowid 1:1 police mtu 4000 rate 1500kbit burst 90k ------ - -which implies "if a packet is seen on the ingress of the lo device with -a source IP address of 127.0.0.1/32 we give it a classification id of 1:1 and -we execute a policing action which rate limits its bandwidth utilization -to 1.5Mbps". - -The new extensions allow for more than just policing actions to be added. -They are also fully backward compatible. If you have a kernel that doesnt -understand them, then the effect is null i.e if you have a newer tc -but older kernel, the actions are not installed. Likewise if you -have a newer kernel but older tc, obviously the tc will use current -syntax which will work fine. Of course to get the required effect you need -both newer tc and kernel. If you are reading this you have the -right tc ;-> - -A side effect is that we can now get stateless firewalling to work with tc. -Essentially this is now an alternative to iptables. -I wont go into details of my dislike for iptables at times, but -scalability is one of the main issues; however, if you need stateful -classification - use netfilter (for now). - -This stuff works on both ingress and egress qdiscs. - -Features --------- - -1) new additional syntax and actions enabled. Note old syntax is still valid. - -Essentially this is still the same syntax as tc with a new construct -"action". The syntax is of the form: -tc filter add parent 1:0 protocol ip prio 10 -flowid 1:1 action * - -You can have as many actions as you want (within sensible reasoning). - -In the past the only real action was the policer; i.e you could do something -along the lines of: -tc filter add dev lo parent ffff: protocol ip prio 10 u32 \ -match ip src 127.0.0.1/32 flowid 1:1 \ -police mtu 4000 rate 1500kbit burst 90k - -Although you can still use the same syntax, now you can say: - -tc filter add dev lo parent 1:0 protocol ip prio 10 u32 \ -match ip src 127.0.0.1/32 flowid 1:1 \ -action police mtu 4000 rate 1500kbit burst 90k - -" generic Actions" (gact) at the moment are: -{ drop, pass, reclassify, continue} -(If you have others, no listed here give me a reason and we will add them) -+drop says to drop the packet -+pass says to accept it -+reclassify requests for reclassification of the packet -+continue requests for next lookup to match - -2)In order to take advantage of some of the targets written by the -iptables people, a classifier can have a packet being massaged by an -iptable target. I have only tested with mangler targets up to now. -(infact anything that is not in the mangling table is disabled right now) - -In terms of hooks: -*ingress is mapped to pre-routing hook -*egress is mapped to post-routing hook -I dont see much value in the other hooks, if you see it and email me good -reasons, the addition is trivial. - -Example syntax for iptables targets usage becomes: -tc filter add ..... u32 action ipt -j - -example: -tc filter add dev lo parent ffff: protocol ip prio 8 u32 \ -match ip dst 127.0.0.8/32 flowid 1:12 \ -action ipt -j mark --set-mark 2 - -3) A feature i call pipe -The motivation is derived from Unix pipe mechanism but applied to packets. -Essentially take a matching packet and pass it through -action1 | action2 | action3 etc. -You could do something similar to this with the tc policer and the "continue" -operator but this rather restricts it to just the policer and requires -multiple rules (and lookups, hence quiet inefficient); - -as an example -- and please note that this is just an example _not_ The -Word Youve Been Waiting For (yes i have had problems giving examples -which ended becoming dogma in documents and people modifying them a little -to look clever); - -i selected the metering rates to be small so that i can show better how -things work. - -The script below does the following: -- an incoming packet from 10.0.0.21 is first given a firewall mark of 1. - -- It is then metered to make sure it does not exceed its allocated rate of -1Kbps. If it doesnt exceed rate, this is where we terminate action execution. - -- If it does exceed its rate, its "color" changes to a mark of 2 and it is -then passed through a second meter. - --The second meter is shared across all flows on that device [i am suprised -that this seems to be not a well know feature of the policer; Bert was telling -me that someone was writing a qdisc just to do sharing across multiple devices; -it must be the summer heat again; weve had someone doing that every year around -summer -- the key to sharing is to use a operator "index" in your policer -rules (example "index 20"). All your rules have to use the same index to -share.] - --If the second meter is exceeded the color of the flow changes further to 3. - --We then pass the packet to another meter which is shared across all devices -in the system. If this meter is exceeded we drop the packet. - -Note the mark can be used further up the system to do things like policy -or more interesting things on the egress. - ------------------- cut here ------------------------------- -# -# Add an ingress qdisc on eth0 -tc qdisc add dev eth0 ingress -# -#if you see an incoming packet from 10.0.0.21 -tc filter add dev eth0 parent ffff: protocol ip prio 1 \ -u32 match ip src 10.0.0.21/32 flowid 1:15 \ -# -# first give it a mark of 1 -action ipt -j mark --set-mark 1 index 2 \ -# -# then pass it through a policer which allows 1kbps; if the flow -# doesnt exceed that rate, this is where we stop, if it exceeds we -# pipe the packet to the next action -action police rate 1kbit burst 9k pipe \ -# -# which marks the packet fwmark as 2 and pipes -action ipt -j mark --set-mark 2 \ -# -# next attempt to borrow b/width from a meter -# used across all flows incoming on eth0("index 30") -# and if that is exceeded we pipe to the next action -action police index 30 mtu 5000 rate 1kbit burst 10k pipe \ -# mark it as fwmark 3 if exceeded -action ipt -j mark --set-mark 3 \ -# and then attempt to borrow from a meter used by all devices in the -# system. Should this be exceeded, drop the packet on the floor. -action police index 20 mtu 5000 rate 1kbit burst 90k drop ---------------------------------- - -Now lets see the actions installed with -"tc filter show parent ffff: dev eth0" - --------- output ----------- -jroot# tc filter show parent ffff: dev eth0 -filter protocol ip pref 1 u32 -filter protocol ip pref 1 u32 fh 800: ht divisor 1 -filter protocol ip pref 1 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:15 - - action order 1: tablename: mangle hook: NF_IP_PRE_ROUTING - target MARK set 0x1 index 2 - - action order 2: police 1 action pipe rate 1Kbit burst 9Kb mtu 2Kb - - action order 3: tablename: mangle hook: NF_IP_PRE_ROUTING - target MARK set 0x2 index 1 - - action order 4: police 30 action pipe rate 1Kbit burst 10Kb mtu 5000b - - action order 5: tablename: mangle hook: NF_IP_PRE_ROUTING - target MARK set 0x3 index 3 - - action order 6: police 20 action drop rate 1Kbit burst 90Kb mtu 5000b - - match 0a000015/ffffffff at 12 -------------------------------- - -Note the ordering of the actions is based on the order in which we entered -them. In the future i will add explicit priorities. - -Now lets run a ping -f from 10.0.0.21 to this host; stop the ping after -you see a few lines of dots - ----- -[root@jzny hadi]# ping -f 10.0.0.22 -PING 10.0.0.22 (10.0.0.22): 56 data bytes -.................................................................................................................................................................................................................................................................................................................................................................................................................................................... ---- 10.0.0.22 ping statistics --- -2248 packets transmitted, 1811 packets received, 19% packet loss -round-trip min/avg/max = 0.7/9.3/20.1 ms ------------------------------ - -Now lets take a look at the stats with "tc -s filter show parent ffff: dev eth0" - --------------- -jroot# tc -s filter show parent ffff: dev eth0 -filter protocol ip pref 1 u32 -filter protocol ip pref 1 u32 fh 800: ht divisor 1 -filter protocol ip pref 1 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1 -5 - - action order 1: tablename: mangle hook: NF_IP_PRE_ROUTING - target MARK set 0x1 index 2 - Sent 188832 bytes 2248 pkts (dropped 0, overlimits 0) - - action order 2: police 1 action pipe rate 1Kbit burst 9Kb mtu 2Kb - Sent 188832 bytes 2248 pkts (dropped 0, overlimits 2122) - - action order 3: tablename: mangle hook: NF_IP_PRE_ROUTING - target MARK set 0x2 index 1 - Sent 178248 bytes 2122 pkts (dropped 0, overlimits 0) - - action order 4: police 30 action pipe rate 1Kbit burst 10Kb mtu 5000b - Sent 178248 bytes 2122 pkts (dropped 0, overlimits 1945) - - action order 5: tablename: mangle hook: NF_IP_PRE_ROUTING - target MARK set 0x3 index 3 - Sent 163380 bytes 1945 pkts (dropped 0, overlimits 0) - - action order 6: police 20 action drop rate 1Kbit burst 90Kb mtu 5000b - Sent 163380 bytes 1945 pkts (dropped 0, overlimits 437) - - match 0a000015/ffffffff at 12 -------------------------------- - -Neat, eh? - - -Wanna write an action module? ------------------------------- -Its easy. Either look at the code or send me email. I will document at -some point; will also accept documentation. - -TODO ----- - -Lotsa goodies/features coming. Requests also being accepted. -At the moment the focus has been on getting the architecture in place. -Expect new things in the spurious time i have to work on this -(particularly around end of year when i have typically get time off -from work). -