mirror of
https://github.com/torvalds/linux
synced 2024-09-22 03:55:39 +00:00
8d11350f5f
It is valid that the TCP RST packet which does not set ack flag, and bytes of ack number are zero. But current seqadj codes would adjust the "0" ack to invalid ack number. Actually seqadj need to check the ack flag before adjust it for these RST packets. The following is my test case client is 10.26.98.245, and add one iptable rule: iptables -I INPUT -p tcp --sport 12345 -m connbytes --connbytes 2: --connbytes-dir reply --connbytes-mode packets -j REJECT --reject-with tcp-reset This iptables rule could generate on TCP RST without ack flag. server:10.172.135.55 Enable the synproxy with seqadjust by the following iptables rules iptables -t raw -A PREROUTING -i eth0 -p tcp -d 10.172.135.55 --dport 12345 -m tcp --syn -j CT --notrack iptables -A INPUT -i eth0 -p tcp -d 10.172.135.55 --dport 12345 -m conntrack --ctstate INVALID,UNTRACKED -j SYNPROXY --sack-perm --timestamp --wscale 7 --mss 1460 iptables -A OUTPUT -o eth0 -p tcp -s 10.172.135.55 --sport 12345 -m conntrack --ctstate INVALID,UNTRACKED -m tcp --tcp-flags SYN,RST,ACK SYN,ACK -j ACCEPT The following is my test result. 1. packet trace on client root@routers:/tmp# tcpdump -i eth0 tcp port 12345 -n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes IP 10.26.98.245.45154 > 10.172.135.55.12345: Flags [S], seq 3695959829, win 29200, options [mss 1460,sackOK,TS val 452367884 ecr 0,nop,wscale 7], length 0 IP 10.172.135.55.12345 > 10.26.98.245.45154: Flags [S.], seq 546723266, ack 3695959830, win 0, options [mss 1460,sackOK,TS val 15643479 ecr 452367884, nop,wscale 7], length 0 IP 10.26.98.245.45154 > 10.172.135.55.12345: Flags [.], ack 1, win 229, options [nop,nop,TS val 452367885 ecr 15643479], length 0 IP 10.172.135.55.12345 > 10.26.98.245.45154: Flags [.], ack 1, win 226, options [nop,nop,TS val 15643479 ecr 452367885], length 0 IP 10.26.98.245.45154 > 10.172.135.55.12345: Flags [R], seq 3695959830, win 0, length 0 2. seqadj log on server [62873.867319] Adjusting sequence number from 602341895->546723267, ack from 3695959830->3695959830 [62873.867644] Adjusting sequence number from 602341895->546723267, ack from 3695959830->3695959830 [62873.869040] Adjusting sequence number from 3695959830->3695959830, ack from 0->55618628 To summarize, it is clear that the seqadj codes adjust the 0 ack when receive one TCP RST packet without ack. Signed-off-by: Gao Feng <fgao@ikuai8.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> |
||
|---|---|---|
| .. | ||
| 6lowpan | ||
| 9p | ||
| 802 | ||
| 8021q | ||
| appletalk | ||
| atm | ||
| ax25 | ||
| batman-adv | ||
| bluetooth | ||
| bridge | ||
| caif | ||
| can | ||
| ceph | ||
| core | ||
| dcb | ||
| dccp | ||
| decnet | ||
| dns_resolver | ||
| dsa | ||
| ethernet | ||
| hsr | ||
| ieee802154 | ||
| ipv4 | ||
| ipv6 | ||
| ipx | ||
| irda | ||
| iucv | ||
| kcm | ||
| key | ||
| l2tp | ||
| l3mdev | ||
| lapb | ||
| llc | ||
| mac80211 | ||
| mac802154 | ||
| mpls | ||
| ncsi | ||
| netfilter | ||
| netlabel | ||
| netlink | ||
| netrom | ||
| nfc | ||
| openvswitch | ||
| packet | ||
| phonet | ||
| qrtr | ||
| rds | ||
| rfkill | ||
| rose | ||
| rxrpc | ||
| sched | ||
| sctp | ||
| strparser | ||
| sunrpc | ||
| switchdev | ||
| tipc | ||
| unix | ||
| vmw_vsock | ||
| wimax | ||
| wireless | ||
| x25 | ||
| xfrm | ||
| compat.c | ||
| Kconfig | ||
| Makefile | ||
| socket.c | ||
| sysctl_net.c | ||