On Tue, Oct 30, 2012 at 11:21:01AM -0600, Jeff Cook wrote:
> Hello.
>
> I am trying to route packets generated by a specific user out over a
> VPN. I have this configuration:
>
> $ sudo iptables -S -t nat
> -P PREROUTING ACCEPT
> -P OUTPUT ACCEPT
> -P POSTROUTING ACCEPT
> -A POSTROUTING -o tun0 -j MASQUERADE
>
> $ sudo iptables -S -t mangle
> -P PREROUTING ACCEPT
> -P INPUT ACCEPT
> -P FORWARD ACCEPT
> -P OUTPUT ACCEPT
> -P POSTROUTING ACCEPT
> -A OUTPUT -m owner --uid-owner guy -j MARK --set-xmark 0xb/0xffffffff
>
> $ sudo ip rule show
> 0: from all lookup local
> 32765: from all fwmark 0xb lookup 11
> 32766: from all lookup main
> 32767: from all lookup default
>
> $ sudo ip route show table 11
> 10.8.0.5 dev tun0 proto kernel scope link src 10.8.0.6
> 10.8.0.6 dev tun0 scope link
> 10.8.0.1 via 10.8.0.5 dev tun0
> 0.0.0.0/1 via 10.8.0.5 dev tun0
^^^^^^^^^
23.1.17.194, this doesn't go through tun0
209.68.27.16, this doesn't go through tun0
Address & CIDR => 209.68.27.16 & 128.0.0.0 => 128.0.0.0
Then: 128.0.0.0 != 0.0.0.0, then go to default route, likely to be
eth0.
> $ sudo iptables -S -t raw
> -P PREROUTING ACCEPT
> -P OUTPUT ACCEPT
> -A OUTPUT -m owner --uid-owner guy -j TRACE
> -A OUTPUT -p tcp -m tcp --dport 80 -j TRACE
>
> It seems that some sites work fine and use the VPN, but others don't and
> fall back to the normal interface. This is bad. This is a packet trace
> that used VPN:
>
> Oct 27 00:24:28 agent kernel: [612979.976052] TRACE:
> raw:OUTPUT:rule:2 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=23.1.17.194
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP SPT=57502 DPT=80
> SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999
> Oct 27 00:24:28 agent kernel: [612979.976105] TRACE:
> raw:OUTPUT:policy:3 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=23.1.17.194
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP SPT=57502 DPT=80
> SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999
> Oct 27 00:24:28 agent kernel: [612979.976164] TRACE:
> mangle:OUTPUT:rule:1 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=23.1.17.194
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP SPT=57502 DPT=80
> SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999
> Oct 27 00:24:28 agent kernel: [612979.976210] TRACE:
> mangle:OUTPUT:policy:2 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=23.1.17.194
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP SPT=57502 DPT=80
> SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999 MARK=0xb
> Oct 27 00:24:28 agent kernel: [612979.976269] TRACE:
> nat:OUTPUT:policy:1 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=23.1.17.194
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP SPT=57502 DPT=80
> SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999 MARK=0xb
> Oct 27 00:24:28 agent kernel: [612979.976320] TRACE:
> filter:OUTPUT:policy:1 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=23.1.17.194
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP SPT=57502 DPT=80
> SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999 MARK=0xb
> Oct 27 00:24:28 agent kernel: [612979.976367] TRACE:
> mangle:POSTROUTING:policy:1 IN= OUT=tun0 SRC=XXX.YYY.ZZZ.AAA
> DST=23.1.17.194 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP
> SPT=57502 DPT=80 SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0
> OPT (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999 MARK=0xb
> Oct 27 00:24:28 agent kernel: [612979.976414] TRACE:
> nat:POSTROUTING:rule:1 IN= OUT=tun0 SRC=XXX.YYY.ZZZ.AAA DST=23.1.17.194
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=14494 DF PROTO=TCP SPT=57502 DPT=80
> SEQ=2294732931 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6E01D0000000001030307) UID=999 GID=999 MARK=0xb
>
> and this is one that didn't:
>
> Oct 27 00:22:41 agent kernel: [612873.662559] TRACE:
> raw:OUTPUT:rule:2 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=209.68.27.16
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=40425 DF PROTO=TCP SPT=45305 DPT=80
> SEQ=604973951 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6B6960000000001030307) UID=999 GID=999
> Oct 27 00:22:41 agent kernel: [612873.662609] TRACE:
> raw:OUTPUT:policy:3 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=209.68.27.16
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=40425 DF PROTO=TCP SPT=45305 DPT=80
> SEQ=604973951 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6B6960000000001030307) UID=999 GID=999
> Oct 27 00:22:41 agent kernel: [612873.662664] TRACE:
> mangle:OUTPUT:rule:1 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=209.68.27.16
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=40425 DF PROTO=TCP SPT=45305 DPT=80
> SEQ=604973951 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6B6960000000001030307) UID=999 GID=999
> Oct 27 00:22:41 agent kernel: [612873.662709] TRACE:
> mangle:OUTPUT:policy:2 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=209.68.27.16
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=40425 DF PROTO=TCP SPT=45305 DPT=80
> SEQ=604973951 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6B6960000000001030307) UID=999 GID=999 MARK=0xb
> Oct 27 00:22:41 agent kernel: [612873.662761] TRACE:
> nat:OUTPUT:policy:1 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=209.68.27.16
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=40425 DF PROTO=TCP SPT=45305 DPT=80
> SEQ=604973951 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6B6960000000001030307) UID=999 GID=999 MARK=0xb
> Oct 27 00:22:41 agent kernel: [612873.662808] TRACE:
> filter:OUTPUT:policy:1 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA DST=209.68.27.16
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=40425 DF PROTO=TCP SPT=45305 DPT=80
> SEQ=604973951 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6B6960000000001030307) UID=999 GID=999 MARK=0xb
> Oct 27 00:22:41 agent kernel: [612873.662855] TRACE:
> mangle:POSTROUTING:policy:1 IN= OUT=eth0 SRC=XXX.YYY.ZZZ.AAA
> DST=209.68.27.16 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=40425 DF PROTO=TCP
> SPT=45305 DPT=80 SEQ=604973951 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT
> (020405B40402080A03A6B6960000000001030307) UID=999 GID=999 MARK=0xb
>
> I have already tried "ip route flush cache", to no avail. I do not know
> why the first packet goes through the correct routing table, and the
> second doesn't. Both are marked.
>
> Once again, I do not want ALL packets system-wide to go through the VPN,
> I only want packets from a specific user (UID=999) to go through the
> VPN. I am testing ipchicken.com and walmart.com via `links`, from the
> same user, same shell. walmart.com appears to use the VPN; ipchicken.com
> does not.
>
> I have tried iptables -t raw -A OUTPUT -j NOTRACK to circumvent
> conntrack interference, but this hasn't worked either.
>
> Any help appreciated; need this resolved ASAP. If this is something that
> can't be resolved by volunteers on a mailing list and someone is
> available as a consultant and can look into this further, would
> appreciate it; email me privately with rate information and credentials.
>
> Thanks
> Jeff
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