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Open Source Routing, Firewalls and Traffic Shaping

Open Source Routing, Firewalls and Traffic Shaping. Russell Sutherland Computing and Networking Services University of Toronto russell.sutherland@utoronto.ca. Reference URLs for Tree Huggers. This presentation http://madhaus.cns.utoronto.ca/~russ/canheit2004/ Routing

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Open Source Routing, Firewalls and Traffic Shaping

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  1. Open Source Routing, Firewalls and Traffic Shaping Russell Sutherland Computing and Networking Services University of Toronto russell.sutherland@utoronto.ca

  2. Reference URLs for Tree Huggers • This presentation • http://madhaus.cns.utoronto.ca/~russ/canheit2004/ • Routing • http://www.quagga.net/ • http://www.xorp.net/ • http://latrc.org/ • Traffic Shaping • Linux http://tcng.sourceforge.net/ • FreeBSD http://info.iet.unipi.it/~luigi/ip_dummynet/ • Packet Filtering • Linux (iptables) http://www.netfilter.org/ • FreeBSD (ipfw) http://www.freebsd.org/ • OpenBSD (pf) http://www.benzedrine.cx/pf.html

  3. Routing Chronology • 1984 BSD 4.2 ships with routed (RIPv1) • 1986 Fuzz Ball PDP-11 NSFNet Routers • 1988 Age of dedicated routing machines • Cisco, Proteon, Wellfleet, ACC • 1992 Gated Consortium Formed • 1996 GNU Zebra • 2002 Quagga, XORP

  4. Quagga Routing Architecture • Modular Design • One process per protocol • bgpd, ospfd, ripd • One main controlling process • zebra • Extensible

  5. Quagga Architecture Diagram ospfd ripd bgpd zebra Unix Kernel Routing Table

  6. Quagga Routing Protocols • RIPv1, RIPv2, RIPng • OSPFv2, OSPFv3 • BGP-4, BGP+ • BGP route server and reflector • IPv6 • Supported RFCs • 1058 RIPv1, 2453 RIPv2, 2080 RIPng • 2328 OSPFv2, 2740 OSPF for Ipv6 • 1771 BGPv4, 1965, 1997, 2545 BGPv6, 2796 BGP Route Reflection, 2858 Multiprotocol extensions, 2842 Capabilities Advertisement

  7. Quagga Supported Platforms • GNU Linux • Debian, RedHat, SuSE, Slackware • Kernels 2.2.x - 2.4.x • FreeBSD • versions 4.x and 5.x • OpenBSD • version 3.x • NetBSD • version 1.4 • Solaris • 2.6 and version 7

  8. Hardware Requirements • CPU Intel 2.0 – 3.0 Ghz • Memory 512MB • Disks 18GB • RAID-1 (optional) • SCSI or IDE • Ethernet Interfaces • 2 x 10/100 Intel, 2 x 10/100/100 Broadcom • Redundancy • hot spare serves as backup to N production units

  9. Scottish Economics • Router Prices • Cisco Mid-size • 7204VxR, Catalyst 3550 • $15k – $32k • Extreme • Alpine 3800 • $31k - $38k • Foundry • BigIron 4000 • $16k • Intel 2.x Ghz server • Dell 2650, IBM x335 • $2.5k - $3.5k

  10. Network Topology Traffic Shaper Cogent A [100Mbps] McL Skye Cogent B [100Mbps] Mull Internal Jura 1. UofT A 2. UofT B 3. ResNet C4 [1000Mbps] Bute Touchdown Network 1000 Mbps External

  11. Network Routing Policy • Three classes of traffic (based on src IP) • ResNet • UofT A • UofT B • ResNet • to (via TS) Skye to Cogent A • No C4 transit !!! • UofT A • to C4 if dst IP == C4 otherwise via Skye to Cog A • UofT B • to C4 if dst IP == C4 otherwise via Mull to CogB

  12. Network Packet Filtering Policies • Drop all packets with • spoofed (non UofT) source IP addresses • non-routable destination addresses • 0.0.0.0/8, 10.0.0.0/8, 127.0.0.0/8 • 169.254.0.0/16, 172.16.0.0/12, 192.168/16 • etc. • nasty tcp/udp M$ worm ports (Blaster, Welchia, etc.) • 67, 68, 69, 135, 137, 139 • 161, 162 • 445, 593, 707, 1433, 1434, 3127, 4444 • non-assigned UofT subnets • Allow everything else

  13. Network Traffic Shaping Policies • All traffic from a local Redhat ftp site to the outside world gets a 50 kbps pipe • Peer to peer traffic to and from UofT A&B gets a 256 kpbs full duplex pipe • KaZaa 1214 • eDonkey 466[12] • BitTorrent 6881-6889 • ResNet traffic gets conditioned by a dedicated Traffic Shaper (Packeteer) • Everything else flows freely

  14. Routing Protocols and Configuration • Jura • runs OSPF on int. intf. with other UofT routers • runs BGP on external interface with C4 peer • contains all UofT and C4 specific routes • Mull • runs OSPF on int. intf. with other UofT routers • runs BGP on external interface with Cogent B peer • advertises UofTB routes • defaults points to Cogent B • Skye • same setup as Mull but with Cogent A • advertises UofTA and ResNet routes

  15. Quagga Routing Configuration • Command line interface similar to Cisco IOS C4# conf t C4(config)# interface eth2 C4(config-if)# description dummy interface C4(config-if)# ip address 10.1.2.3/24 C4(config-if)# exit C4(config)# exit C4# C4# conf t C4(config)# router bgp 328 C4(config-router)# bgp router-id 10.1.1.10 C4(config-router)# network 10.1.1.0/24 C4(config-router)# redistribute static C4(config-router)# neighbor 10.1.1.1 remote-as 999 C4(config-router)# exit C4(config)# exit C4#

  16. Quagga Operation # show ip route Codes: K - kernel route, C – connected, S – static, O -OSPF B – BGP, > - selected route, * FIB route S>* 0.0.0.0/0 [10/0] via 128.100.96.194, disc0 B>* 6.1.0.0/16 [20/0] via 205.211.94.97, yk0, 01w4d03h B>* 6.2.0.0/22 [20/0] via 205.211.94.97, yk0, 01w4d03h B>* 6.3.0.0/18 [20/0] via 205.211.94.97, yk0, 01w4d03h # show bgp neighbors BGP neighbor is 205.211.94.97, remote AS 549, local AS 239, external link BGP version 4, remote router ID 205.211.94.253 BGP state = Established, up for 01w4d22h

  17. FreeBSD ipfw Packet Filtering • Native packet filtering interface • Implemented as a multifunction user command • The packet passed to the firewall is compared against each of the rules in the firewall ruleset. • When a match is found, the action corresponding to the matching rule is performed and the search terminates. • General syntax • ipfw [rule number] action [log] body

  18. ipfw examples • Drop all www traffic from a network • ipfw add deny tcp from 12.12.12.0/24 to www.ubc.ca 80 • Drop all telnet traffic from a bad host • ipfw add deny tcp from bad.host.com to my.host.com 23 • Throw away RFC 1918 networks • ipfw add deny all from 10.0.0.0/8 to any in via fxp0 • ipfw add deny all from 172.16.0.0/12 to any in via fxp0 • ipfw add deny all from 192.168.0.0/16 to any in via fxp0 • Allow ssh • ipfw add allow tcp from any to any 22 in via fxp0 setup keep-state

  19. ipfw actions • allow | accept | pass | permit • Allow packets that match rule. The search ends. • deny | drop • Discard packets that match rule. The search ends. • fwd | forward ipaddr[,port] • Change the next-hop on matching pckts to ipaddr • pipe N • Pass packet to a dummynet(4) for bandwidth limitation. [ conditionally end or continue ] • count • Update counters for all packets that match rule. The search continues with the next rule

  20. Traffic Control Concepts I • Set of mechanisms to condition net traffic • Examples • raise priority of some kinds of traffic • limit the rate at which traffic is sent • block undesirable traffic (same as packet filtering) • TC is done at the network interface • ingress (traffic entering an interface) • limited set of functions (classifying, dropping) • egress (traffic leaving an interface) • full range of functions available • queueing

  21. Traffic Control Concepts II Classification Queueing Scheduling

  22. Traffic Control Concepts III • Classification • looks at packet content and assigns each to one or more classes. • Queueing • stuffs incoming packets into storage silos based on class • Scheduling • transmitting packets in queues based upon priority • Queueing and Scheduling are often combined into queuing disciplines

  23. Traffic Control Concepts IV • Common Queueing Disciplines • simple drop tail (FIFO) • stores and emits packets in order which they arrive • Random Early Detection (RED) • starts dropping packets already before reaching maximum queue size • Token Bucket Filter (TBF) • shapers that emits packets at a fixed rate • Priority Scheduler (PQ) • emits packets in higher priority classes before packets in lower priority classes • Weighted Fair Queueing (WFQ) • assigns an independent queue for each flow • a weight can be defined for each queue

  24. FreeBSD Dummynet Features • Integrated with ipfw to classify packets • Can be used equally well on egress/ingress • Abstractions/features • pipes • fixed bandwidth channels • variable queue size, delays, random packet loss • queues • queues of packets • weighted • share bandwidth of pipe they are associated with proportionally to their weight • WF2Q+ used for queuing discipline

  25. Dummynet Examples • Limit WWW traffic to 100Mbps • ipfw pipe 1 config bw 100Mbit/s • ipfw add pipe 1 ip from any to any dst-port 80 • Prefer ssh to telnet traffic • ipfw pipe 2 config bw 256kbit/s • ipfw queue 1 config pipe 2 weight 7 • ipfw queue 2 config pipe 2 weight 3 • ipfw add queue 1 ip from any to any dst-port 22 • ipfw add queue 2 ip from any to any dst-port 23 • Rate limit each network host's upload rate • ipfw pipe 3 config mask src-ip 0x000000ff bw 16kbit/s queue 8Kbytes • ipfw add pipe 3 ip from 12.18.123.0/24 to any out via xl0

  26. Routing Policy Using ipfw • All ResNet traffic forwarded directly to Skye • ipfw add fwd $skye from $resnet to any in recv $uoft_if • Block spoofed packets • ipfw add allow all from $uoftnet to any in recv $uoft_if • ipfw add deny in recv $uoft_if • Block bad packets (M$ worms etc.) • for i in 67-69 135-139 161 162 445 593 707 4444 • do • ipfw add deny udp from any to any $i • ipfw add deny tcp from any to any $i • done • C4 traffic follows specific routes from BGP

  27. Routing Policy Using ipfw Cont. • Block all traffic to non-defined UofT addrs • ipfw add deny all from any to $uoftnet out xmit $def_if • Partition UofT A/B traffic to Skye/Mull • add fwd $skye all from $uoftA to any out xmit $def_if • add fwd $mull all from $uoftB to any out xmit $def_if • Traffic Shaping • limit RH ftp server • ipfw pipe 1 config bw 50Kbit/s • ipfw add pipe 1 ip from $rhftp to any in recv $uoftif • limit peer to peer • ipfw pipe 2 config bw 256 Kbit/s • ipfw add pipe 2 ip from $uoftA to any dst_port 1214,4661,4662

  28. Linux Packet Filtering: iptables • Similar to ipfw in functionality and use • User based command line interface • Syntax • iptables rule-action table name conditions action • Very rich set of conditions and actions • Extensible modular actions • More complicated in concept than ipfw or pf • hierarchy: tables -> chains -> rules • three default tables with default policies • filter, nat, mangle

  29. Linux iptables Anatomy Ingress Network Interface Contrack mangle IMQ nat INPUT ROUTING and RPDB mangle mangle filter filter LOCAL PROCESSES REMOTE IP ADDR PREROUTING QOS Ingress INPUT FORWARD

  30. Linux iptables Anatomy Egress LOCAL PROCESSES OUTPUT ROUTING REMOTE IP ADDR contrack mangle nat filter Network Interface OUTPUT mangle POSTROUTING nat IMQ QOS Egress

  31. iptables examples • Drop all www traffic from a network • iptables -A FORWARD -p tcp –dport 80 -s 12.12.12.0/24 -d www.ubc.ca -j DROP • Drop all telnet traffic from a bad host • iptables -A INPUT -p tcp -s bad.host.com -d my.host.com –-dport 23 -j DROP • Throw away RFC 1918 networks from inside • iptables -A FORWARD -s 10.0.0.0/8 -i eth0 -j DROP • iptables -A INPUT -s 10.0.0.0/8 -i eth0 -j DROP • iptables -t mangle -A PREROUTING -s 172.16.0.0/12 -i eth0 -j DROP • Allow ssh and keep state • iptables -A FORWARD -p tcp –dport 22 -i fxp0 -m state -–state NEW,ESTABLISHED -j ACCEPT

  32. Linux Routing – Multiple Tables • Multiple routing/forwarding tables • Three fixed prefined tables • local • main • default • Each table is assigned a priority number • 0 local • 32766 main • 32767 default • match is sought starting with highest priority tables (local -> main -> default)

  33. Linux Routing Policy Database

  34. Linux Traffic Control: tc • Uses queueing disciplines for managing bandwidth • Largely concerned with data being sent rather than received. • Classless queueing disciplines • reschedule, drop or delay • applied to the bulk interface • pfifo_fast • default, can't be changed • TBF (Token Bucket Filter) • passes traffic up to a fixed rate • drops the rest • allows short burst in excess of fixed rate

  35. tc: Classless qdiscs • SFQ (Stocastic Fair Queueing) • Traffic split into large number of FIFO queues, one per flow • Traffic gets sent/serviced in a round robin fashion, giving each flow a chance to sent its data. • Leads to fair behaviour • prevents one flow from hogging all the bandwidth • only really useful when the link is full • RED (Random Early Detection) • drops packets statistically before queues are full • leads to a congested link to slow more gracefully • helps TCP applications find their fair speed faster

  36. tc: Classful qdiscs • Used when different types of traffic need different treatment. • CBQ (Class Based Queueing) • very complicated to set up and tune • PRIO • classify and traffic into a number of bands each with its own priority. • u32 • used as the tool to classify the traffic into sub queues • based on actual offset of information in the IP header

  37. Linux: tcng • tc syntax is very complicated both in setting up the qdisc's and classification • tc qdisc add dev eth0 root handle 1:0 prio • tc qdisc add dev eth0 parent 1:0 protocol ip u32 match ip protocol 6 ff match tcp dst 50 ffff classid 1:1 • tc qdisc add dev eth0 parent 1:3 handle 30: sfq • tc filter add dev eth0 parent 1:0 protocol ip prio 1 u32 match ip sport 80 0xffff flowid 1:3 • tcng was created as a higher level tool • simple to configure • more natural language to set up classes and qdisc • compiles to tc or “C” • comes with a simulator

  38. tcng: Example Input dev “eth0” { egress { class (<$high>) if tcp_port == 80; class (<$low>) if 1; prio { $high = class { tbf(limit 10kB, rate 20kbps, burst 2kB, mtu 1500B); $low = class { fifo(limit 30kB) } } } }

  39. tcng: Example Output tc qdisc add dev eth0 handle 1:0 root dsmark indices 4 default_index 0 tc qdisc add dev eth0 handle 2:0 parent 1:0 prio tc qdisc add dev eth0 handle 3:0 parent 2:1 tbf burst 2048 limit 10240 mtu 1500 rate 2500bps tc qdisc add dev eth0 handle 4:0 parent 2:2 bfifo limit 30720 tc filter add dev eth0 parent 2:0 protocol all prio 1 tcindex mask 0x3 shift 0 tc filter add dev eth0 parent 2:0 protocol all prio 1 handle 2 tcindex classid 2:2 tc filter add dev eth0 parent 2:0 protocol all prio 1 handle 1 tcindex classid 2:1 tc filter add dev eth0 parent 1:0 protocol all prio 1 handle 1:0:0 u32 divisor 1 tc filter add dev eth0 parent 1:0 protocol all prio 1 u32 match u8 0x6 0xff at 9 offset at 0 mask 0f00 shift 6 eat link 1:0:0 tc filter add dev eth0 parent 1:0 protocol all prio 1 handle 1:0:1 u32 ht 1:0:0 match u16 0x50 0xffff at 2 classid 1:1 tc filter add dev eth0 parent 1:0 protocol all prio 1 u32 match u32 0x0 0x0 at 0 classid 1:2

  40. Routing Policy Using Linux • Routing Tables • 0: from all lookup local • 100: from 142.151.0.0/16 lookup resnet • 1000: from all lookup main • 2000: from 142.150.0.0/16 lookup uoftA • 32767: from all lookup default • resnet contains a single default to syke • uoftA contains a default to skye • default contains a default to mull • main contains all the C4 routes

  41. Linux Traffic Shaping Policy dev eth1 { egress { class ( <$rhftp> ) if ip_src == 128.100.17.10; class ( <$p2p> ) if ( (tcp_dport == 1214 || tcp_dport == 4661 || tcp_dport == 4662) && ip_src:16 == 128.100.0.0 ); class ( <$high> ) if 1 ; htb () { class ( rate 100Mbps , ceil 100Mbps ) { $rhftp = class ( rate 50kbps, ceil 75kbps ); $p2p = class ( rate 256kbps, ceil 325kbps ); $high = class ( rate 90Mbps, ceil 100Mbps ); } } } }

  42. OpenBSD packet filtering • pf runs as the native packet filtering engine • similar in syntax to ipfw • traffic shaping (ALTQ) integrated with pf • BSD only supports one main routing table • pf (like ipfw) supports a forwarding action to explicitly forward a packet • URLs • www.openbsd.org • www.csl.sony.co.jp/person/kjc/software.html • www.benzedrene.cx/pf.html

  43. Results and Conclusions • OSS Routers in service for > 18 months • Scaled easily from 1 to 3 machines • Currently running • FreeBSD 4.x, 5.x, dummynet, ipfw • Will be moving to Linux in next 3 months • Standard network monitoring via SNMP • CPU running < 40% • OSS is a viable option for policy based routing and shaping at the edge

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