Mystery Guest on my subnet.

Mystery Guest on my subnet.

Post by Sudd » Sun, 09 Jul 2000 04:00:00



Can anyone figure out why someone would want to do this for MONTHS:  (Over
half a year now!)

tcpdump shows:

13:39:15.227310 0:e0:29:47:25:6b Broadcast ip 60: 5.0.0.4.2301 >
255.255.255.255.2301: udp 12
13:39:53.199088 0:e0:29:47:25:6b Broadcast ip 60: 24.19.207.26.2301 >
255.255.255.255.2301: udp 12
13:40:15.204580 0:e0:29:47:25:6b Broadcast ip 60: 5.0.0.4.2301 >
255.255.255.255.2301: udp 12
13:40:19.161950 0:e0:29:47:25:6b Broadcast arp 60: arp who-has 24.19.207.1
tell 24.19.207.26
13:40:53.218519 0:e0:29:47:25:6b Broadcast ip 60: 24.19.207.26.2301 >
255.255.255.255.2301: udp 12
13:41:15.229264 0:e0:29:47:25:6b Broadcast ip 60: 5.0.0.4.2301 >
255.255.255.255.2301: udp 12
13:41:53.241442 0:e0:29:47:25:6b Broadcast ip 60: 24.19.207.26.2301 >
255.255.255.255.2301: udp 12

Notice that there are two IP addresses and only 1 MAC address.  Further an
NSLOOKUP of 24.19.207.26 reveals nothing.  Im pretty sure that its part of

64 bytes from 24.19.207.26: icmp_seq=1 ttl=127 time=1363.1 ms
64 bytes from 24.19.207.26: icmp_seq=2 ttl=127 time=1173.3 ms
64 bytes from 24.19.207.26: icmp_seq=3 ttl=127 time=1293.9 ms
64 bytes from 24.19.207.26: icmp_seq=4 ttl=127 time=1030.8 ms
64 bytes from 24.19.207.26: icmp_seq=5 ttl=127 time=1150.6 ms
64 bytes from 24.19.207.26: icmp_seq=6 ttl=127 time=964.6 ms

But look at those times!  Not what I would expect from a PC on my subnet.
(Which would be the only way a broadcast could show up.)

Traceroute gives:
traceroute to 24.19.207.26 (24.19.207.26), 30 hops max, 38 byte packets
 1  r1-fe1-0-100bt.olmpi1.wa.home.net (24.1.26.1)  24.416 ms  18.972 ms
22.063 ms
2 24.19.207.26 (24.19.207.26)  2302.833 ms  1203.157 ms  1532.508 ms

Any ideas?

 
 
 

Mystery Guest on my subnet.

Post by Tim Hayn » Sun, 09 Jul 2000 04:00:00



> 13:39:15.227310 0:e0:29:47:25:6b Broadcast ip 60: 5.0.0.4.2301 >
> 255.255.255.255.2301: udp 12

What interface of yours was this on? Fear greatly, for 5.0.0.0/8 is a class
A network reserved by IANA; if you see stuff coming or going from/to it,
worry.

Quote:> 13:39:53.199088 0:e0:29:47:25:6b Broadcast ip 60: 24.19.207.26.2301 >
> 255.255.255.255.2301: udp 12

UDP broadcasts? What are you running that would do that sort of thing? In
particular, what that would want to do it at 15 and 53s past the minute?

> Notice that there are two IP addresses and only 1 MAC address.  Further
> an NSLOOKUP of 24.19.207.26 reveals nothing.  Im pretty sure that its



Quote:> 64 bytes from 24.19.207.26: icmp_seq=1 ttl=127 time=1363.1 ms
> 64 bytes from 24.19.207.26: icmp_seq=2 ttl=127 time=1173.3 ms

> But look at those times!  Not what I would expect from a PC on my subnet.
> (Which would be the only way a broadcast could show up.)

Er... no, broadcasts would show up if your router is fscked. Routers

who knows?

If those things with IP# 5.0.0.4 were coming from inside your network,

to get their act together.

~Tim
--
| Geek Code: GCS dpu s-:+ a-- C++++ UBLUAVHSC++++ P+++ L++ E--- W+++(--) N++
| w--- O- M-- V-- PS PGP++ t--- X+(-) b D+ G e++(*) h++(*) r--- y-          
| The sun is melting over the hills,         | http://piglet.is.dreaming.org/


 
 
 

Mystery Guest on my subnet.

Post by Doug Holt » Sun, 09 Jul 2000 04:00:00


I did a whois on 5.0.0.4 and got an email server at emecube.com
Doug Holtz

> Can anyone figure out why someone would want to do this for MONTHS:  (Over
> half a year now!)

> tcpdump shows:

> 13:39:15.227310 0:e0:29:47:25:6b Broadcast ip 60: 5.0.0.4.2301 >
> 255.255.255.255.2301: udp 12
> 13:39:53.199088 0:e0:29:47:25:6b Broadcast ip 60: 24.19.207.26.2301 >
> 255.255.255.255.2301: udp 12
> 13:40:15.204580 0:e0:29:47:25:6b Broadcast ip 60: 5.0.0.4.2301 >
> 255.255.255.255.2301: udp 12
> 13:40:19.161950 0:e0:29:47:25:6b Broadcast arp 60: arp who-has 24.19.207.1
> tell 24.19.207.26
> 13:40:53.218519 0:e0:29:47:25:6b Broadcast ip 60: 24.19.207.26.2301 >
> 255.255.255.255.2301: udp 12
> 13:41:15.229264 0:e0:29:47:25:6b Broadcast ip 60: 5.0.0.4.2301 >
> 255.255.255.255.2301: udp 12
> 13:41:53.241442 0:e0:29:47:25:6b Broadcast ip 60: 24.19.207.26.2301 >
> 255.255.255.255.2301: udp 12

> Notice that there are two IP addresses and only 1 MAC address.  Further an
> NSLOOKUP of 24.19.207.26 reveals nothing.  I'm pretty sure that it's part
of

> 64 bytes from 24.19.207.26: icmp_seq=1 ttl=127 time=1363.1 ms
> 64 bytes from 24.19.207.26: icmp_seq=2 ttl=127 time=1173.3 ms
> 64 bytes from 24.19.207.26: icmp_seq=3 ttl=127 time=1293.9 ms
> 64 bytes from 24.19.207.26: icmp_seq=4 ttl=127 time=1030.8 ms
> 64 bytes from 24.19.207.26: icmp_seq=5 ttl=127 time=1150.6 ms
> 64 bytes from 24.19.207.26: icmp_seq=6 ttl=127 time=964.6 ms

> But look at those times!  Not what I would expect from a PC on my subnet.
> (Which would be the only way a broadcast could show up.)

> Traceroute gives:
> traceroute to 24.19.207.26 (24.19.207.26), 30 hops max, 38 byte packets
>  1  r1-fe1-0-100bt.olmpi1.wa.home.net (24.1.26.1)  24.416 ms  18.972 ms
> 22.063 ms
> 2 24.19.207.26 (24.19.207.26)  2302.833 ms  1203.157 ms  1532.508 ms

> Any ideas?

 
 
 

1. 2 ip adresses, different subnet, ping reply from ip in other subnet ?

Hi,

I have a linux server with 2 nic's both in a separate subnet (172.21.3.x
and 192.168.10.x).

the 192.168.10.x is connected to another server via a crossed utp cable.
the 172.21.3 is our local lan.

if i ping the 192.168.10.x interface on the server from my local
workstation (which is in the 172.21.3.x range), i get an immediate reply.

How does this happen ? does the linux server hear the request for
192.168.10.x on his 172.21.3.x interface and thinks, "hey, that's my other
interface, i'll reply" ?

in the routing table, there is no reference to the 192.168.10.x subnet,
and our default gateway also doesn't know about this subnet.

if my assumptions are correct, is it possible to stop the linux server
from responding to icmp queries not directed to its correct (same subnet)
interface ?

I don't use iptables (yet). i noticed the same behaviour with the
/proc/sys/net/ipv4/ip_forward parameter either set to 0 or 1.

Thanks,

Tom.

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