linux - Send raw IP packet with tun device -


i'm trying programmatically construct , send ip packet through tun device.

i've setup tun device , proper routes:

# ip tuntap add mode tun tun0 # ip link set tun0 # ip addr add 10.0.0.2/24 dev tun0

which results in:

$ route -n kernel ip routing table destination     gateway         genmask         flags metric ref    use  iface 0.0.0.0         192.168.0.1     0.0.0.0         ug    600    0        0 wlp3s0 10.0.0.0        0.0.0.0         255.255.255.0   u     0      0        0 tun0 192.168.0.0     0.0.0.0         255.255.255.0   u     600    0        0 wlp3s0  $ ifconfig tun0 tun0: flags=4241<up,pointopoint,noarp,multicast>  mtu 1500     inet 10.0.0.2  netmask 255.255.255.0  destination 10.0.0.2     inet6 fe80::f834:5267:3a1:5d1d  prefixlen 64  scopeid 0x20<link>     unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 500  (unspec)

ip forwarding on: # echo 1 > /proc/sys/net/ipv4/ip_forward

i've setup nat tun0 packets:

# iptables -t nat -a postrouting -s 10.0.0.0/24 -o wlp3s0 -j masquerade # iptables -t nat -l -v chain postrouting (policy accept 0 packets, 0 bytes) pkts bytes target     prot opt in     out     source               destination                    0     0 masquerade   --     wlp3s0  10.0.0.0/24          anywhere

then have python script produce icmp packets:

import os fcntl import ioctl import struct import time import random  # pip install pypacker==4.0 pypacker.layer3.ip import ip pypacker.layer3.icmp import icmp  tunsetiff = 0x400454ca iff_tun   = 0x0001 iff_no_pi = 0x1000  ftun = os.open("/dev/net/tun", os.o_rdwr) ioctl(ftun, tunsetiff, struct.pack("16sh", b"tun0", iff_tun | iff_no_pi))  req_nr = 1 req_id = random.randint(1, 65000) while true:     icmp_req = ip(src_s="10.0.0.2", dst_s="8.8.8.8", p=1) +\         icmp(type=8) +\         icmp.echo(id=req_id, seq=req_nr, body_bytes=b"povilas-test")     os.write(ftun, icmp_req.bin())     time.sleep(1)     req_nr += 1

i can see packets originating tun0 interface:

# tshark -i tun0 1 0.000000000     10.0.0.2 → 8.8.8.8      icmp 48 echo (ping) request  id=0xb673, seq=1/256, ttl=64 2 1.001695939     10.0.0.2 → 8.8.8.8      icmp 48 echo (ping) request  id=0xb673, seq=2/512, ttl=64 3 2.003375319     10.0.0.2 → 8.8.8.8      icmp 48 echo (ping) request  id=0xb673, seq=3/768, ttl=6

but wlp3s0 interface silent, seems packets don't nat'ed , routed wlp3s0 interface, wlan card.

any ideas missing?

i'm running debian 9. , turns out packet forwarding disabled - default policy forward chain drop:

# iptables -l -v chain forward (policy drop 0 packets, 0 bytes)  pkts bytes target     prot opt in     out     source               destination

so changed policy: 

# iptables -p forward accept chain forward (policy accept 0 packets, 0 bytes)  pkts bytes target     prot opt in     out     source               destination

also, had change ip packet source address other 10.0.0.2 preferred source address tun0 interface:

$ ip route 10.0.0.0/24 dev tun0 proto kernel scope link src 10.0.0.2

so changed packet source address 10.0.0.4:

icmp_req = ip(src_s="10.0.0.4", dst_s="8.8.8.8", p=1) +\     icmp(type=8) +\     icmp.echo(id=req_id, seq=req_nr, body_bytes=b"povilas-test")

then kernel started forwarding packets coming tun0 interface gateway interface:

# tshark -i wlp3s0  5 0.008428567 192.168.0.103 → 8.8.8.8      icmp 62 echo (ping) request  id=0xb5c7, seq=9/2304, ttl=63 6 0.041114028      8.8.8.8 → 192.168.0.103 icmp 62 echo (ping) reply    id=0xb5c7, seq=9/2304, ttl=48 (request in 5)

also ping responses sent tun0:

# tshark -i tun0  1 0.000000000     10.0.0.4 → 8.8.8.8      icmp 48 echo (ping) request  id=0xb5c7, seq=113/28928, ttl=64 2 0.035470191      8.8.8.8 → 10.0.0.4     icmp 48 echo (ping) reply    id=0xb5c7, seq=113/28928, ttl=47 (request in 1)

Comments

Post a Comment

Popular posts from this blog

python - Operations inside variables -

this question has answer here: evaluating mathematical expression in string 12 answers i want make python script finds maximum possible output using 2 operations. problem says there syntax error @ 2nd last line, in b in there. how can fix it? x = 0 = int(input("1st number:")) c = int(input("2nd number:" )) e = int(input("3rd number:" )) in range(4): if == 0: b = "+" elif == 1: b = "-" elif == 2: b = "/" else: b = "*" j in range(4): if j == 0: d = "+" elif j == 1: d = "-" elif j == 2: d = "/" else: d = "*" k = b c d e print(k) if you're after variables e on single line, couldn...
Read more

Generic Map Parameter java -

i having lot of methods of type: public static list<eduusers> getdetails(class c, map<string, integer> params) { list<eduusers> details = null; session session = hibernateutil.getsessionfactory().opensession(); transaction tx = null; try { tx = session.begintransaction(); criteria cr = session.createcriteria(c); (map.entry<string, integer> entry : params.entryset()) { cr.add(restrictions.eq(entry.getkey(), entry.getvalue())); } details = cr.list(); tx.commit(); } catch (exception asd) { log.debug(asd.getmessage()); if (tx != null) { tx.commit(); } } { session.close(); } return details; } i trying have generic method them , have written far: public static <t> list<t> getdetails(class<t> c, class<t> b) { l...
Read more

arrays - What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it? -

what arrayindexoutofboundsexception mean , how rid of it? here code sample triggers exception: string[] name = {"tom", "dick", "harry"}; for(int = 0; i<=name.length; i++) { system.out.print(name[i] +'\n'); } your first port of call should documentation explains reasonably clearly: thrown indicate array has been accessed illegal index. index either negative or greater or equal size of array. so example: int[] array = new int[5]; int boom = array[10]; // throws exception as how avoid it... um, don't that. careful array indexes. one problem people run thinking arrays 1-indexed, e.g. int[] array = new int[5]; // ... populate array here ... (int index = 1; index <= array.length; index++) { system.out.println(array[index]); } that miss out first element (index 0) , throw exception when index 5. valid indexes here 0-4 inclusive. correct, idiomatic for statement here be: for (int index = 0; index <...
Read more