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List:       linux-net
Subject:    Re: No telnet-rlogin-ftp
From:       Peter Leif Rasmussen <peter () udgaard ! isgtec ! com>
Date:       1997-07-30 2:04:14
[Download RAW message or body]

Meir wrote:
> Peter Leif Rasmussen wrote:
<snip>
> > 
> > IP address       HW type     Flags       HW address            Mask     Device
> > 192.168.1.1      0x1         0x2         00:00:21:B7:45:88     *        eth0
<snip>
> > IP address       HW type     Flags       HW address            Mask     Device
> > 192.168.1.3      0x1         0x2         21:B7:21:B7:45:83     *        eth0
> 					   ~~~~~~~~
> In a precedent email you write that your network cards are 2 identicals
> NE2000, rigth ? Given that the first 3 bytes of your hardware address 
> identify a network card vendor, can one tell why this 3 bytes differ and
> if it's ok ? 
I don't know what is correct and what it should be, but I can confirm that the
noted hardware addresses are what ifconfig and /proc/net/arp says.

> 
> Peter, could you please send a tcpdump of say a telnet tentative, I 
> think it might help. 

When listening on one host with tcpdump and attempting a telnet from the other
side, the following appears:           (hostnames are "udgaard" and "ida")

udgaard:~# tcpdump
tcpdump: listening on eth0
21:40:49.849752 ida.1038 > udgaard.isgtec.com.telnet: S 1568927272:1568927272(0) win \
512 <mss 1460> [tos 0x10] 21:40:49.849752 arp who-has ida tell udgaard.isgtec.com
21:40:49.849752 arp reply ida is-at 21:b7:21:b7:45:83
21:40:49.849752 udgaard.isgtec.com.telnet > ida.1038: S 3824969475:3824969475(0) ack \
                1568927273 win 31744 <mss 1460>
21:40:52.839752 ida.1038 > udgaard.isgtec.com.telnet: S 1568927272:1568927272(0) win \
                15360 <mss 1460> [tos 0x10]
21:40:52.849752 udgaard.isgtec.com.telnet > ida.1038: S 3824969475:3824969475(0) ack \
                1568927273 win 31744 <mss 1460>
21:40:58.839752 ida.1038 > udgaard.isgtec.com.telnet: S 1568927272:1568927272(0) win \
                15360 <mss 1460> [tos 0x10]
21:40:58.849752 udgaard.isgtec.com.telnet > ida.1038: S 3824969475:3824969475(0) ack \
                1568927273 win 31744 <mss 1460>
21:41:10.839752 ida.1038 > udgaard.isgtec.com.telnet: S 1568927272:1568927272(0) win \
                15360 <mss 1460> [tos 0x10]
21:41:10.849752 udgaard.isgtec.com.telnet > ida.1038: S 3824969475:3824969475(0) ack \
                1568927273 win 31744 <mss 1460>
21:41:34.829752 ida.1038 > udgaard.isgtec.com.telnet: S 1568927272:1568927272(0) win \
                15360 <mss 1460> [tos 0x10]
21:41:34.849752 udgaard.isgtec.com.telnet > ida.1038: S 3824969475:3824969475(0) ack \
                1568927273 win 31744 <mss 1460>
21:42:22.849752 udgaard.isgtec.com.telnet > ida.1038: S 3824969475:3824969475(0) ack \
1568927273 win 31744 <mss 1460>

13 packets received by filter
0 packets dropped by kernel

It was stopped with Ctrl-C on both sides.

If I on the other hand does a ping from the other side (ida) and listens with
tcpdump on this side (udgaard) the following appears:

udgaard:~# tcpdump
tcpdump: listening on eth0
21:51:06.569752 ida > udgaard.isgtec.com: icmp: echo request
21:51:06.569752 udgaard.isgtec.com > ida: icmp: echo reply
21:51:07.569752 ida > udgaard.isgtec.com: icmp: echo request
21:51:07.569752 udgaard.isgtec.com > ida: icmp: echo reply
21:51:08.569752 ida > udgaard.isgtec.com: icmp: echo request
21:51:08.569752 udgaard.isgtec.com > ida: icmp: echo reply
21:51:09.569752 ida > udgaard.isgtec.com: icmp: echo request
21:51:09.569752 udgaard.isgtec.com > ida: icmp: echo reply
21:51:10.569752 ida > udgaard.isgtec.com: icmp: echo request
21:51:10.569752 udgaard.isgtec.com > ida: icmp: echo reply
21:51:44.769752 arp who-has udgaard.isgtec.com tell ida
21:51:44.769752 arp reply udgaard.isgtec.com is-at 0:0:21:b7:45:88
21:51:58.849752 udgaard.isgtec.com.telnet > ida.1038: S 3824969475:3824969475(0) ack \
1568927273 win 31744 <mss 1460>

13 packets received by filter
0 packets dropped by kernel

I don't know what the telnet packet is doing after the ping has finished
(executed as:  ping -c 5 udgaard), but I tried it two times and they both
finished like this (the tcpdump was stopped with Ctrl-C) after waiting a few
seconds. My /etc/hosts on udgaard and ida are like this:

127.0.0.1	localhost
192.168.1.1	 	udgaard.isgtec.com udgaard
192.168.1.3	 	ida

Lets hope this clarifies what may be wrong :-)

Thank you very much for your time,

Peter
--
main(){char*s="O_>>^PQAHBbPQAHBbPOOH^^PAAHBJPAAHBbPA_H>BB";int i,j,k,l,m,n;
for(j=0;j<7;j++)for(l=0;m=l-6+j,i=m/6,n=j*6+i,k=1<<m%6,l<41-j;l++)
putchar(l<6-j?' ':l==40-j?'\n':k&&s[n]&k?'*':' ');}


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