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rsh remote shell problem

Posted on 2005-04-13
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Last Modified: 2013-12-27
We are recently having remote call( rsh ) problems from server1 to server2.

We have setup the followings on server2:

/usr/sbin/ndd -set /dev/ge instance 0  
/usr/sbin/ndd -set /dev/ge adv_1000fdx_cap 1  
/usr/sbin/ndd -set /dev/ge adv_1000hdx_cap 0  
/usr/sbin/ndd -set /dev/ge adv_pauseTX 1  
/usr/sbin/ndd -set /dev/ge adv_pauseRX 1  
/usr/sbin/ndd -set /dev/ge adv_1000autoneg_cap 0

/usr/sbin/ifconfig ge0 105.15.15.235 netmask 255.255.255.0


It worked fine but then suddenly break off. So the guess is something happened on server1. Could anyone tell what can be fixed. Here is the version of server1: SunOS c28temuxs06 5.8 Generic_108528-23 sun4u sparc SUNW,Sun-Fire-280R

Thanks
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Question by:ebi168
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44 Comments
 
LVL 10

Expert Comment

by:Nukfror
ID: 13778510
I would do a couple of things to help diagnosis this:

- Truss the inet on server2
- Truss rsh on server1
- Snoop network for rsh traffic between server1 and server2

This may help you determine where the problem is coming from.
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Expert Comment

by:Nukfror
ID: 13778548
Actually I just noticed you've posted two questions that may be related.

If you "cannot establish link" and this rsh issue happening on the same server ?

If you've forced the interface and you're still getting link issues a couple of things come to mind:

- Cable - get a factory made CAT5E cable and try that
- Try changing ports on the switch
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Expert Comment

by:neteducation
ID: 13800953
You write "it worked fine but then suddenly break off"

do you mean in the middle of the transmision? or do you mean it worked until day x and since then it's no longer working ?
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Expert Comment

by:eddie81
ID: 13816667
I have actually seen various causes of "it worked fine but then suddenly break off" namely :-
- faulty network cable
- faulty network point
- faulty port on the switch/hub
- one of the system - REBOOT/SHUT DOWN
- IP address conflict
etc. etc.

First, I would like to know if this problem ONLY happens with rsh from server1 to server2. What about, say, rsh from server1 to server3?

Can server 2 "ping" to server 3? or
Can server 1 "ping" to server 3?

If server 1 has problem to ping to server 3, then we know server1 is the culprit.

- check if both system is still up & running at that time. (to eliminate the "one of the system - REBOOT/SHUT DOWN" )

- plug off server 1 from network, then use server3 to ping the IP Address of server1. Continue for server 2. (to eliminate the "IP address conflict")

- change the port on the switch/port (to eliminate "faulty port on the switch/hub")

- change network cable.

Let me know if the problem still exist the after the initial troubleshooting as above.
0
 

Author Comment

by:ebi168
ID: 13880048
Thanks for all your information.

Here is more facts that makes me doubt it is caused by cable problems--

We setup these things on server 2 to make rsh work from server 1:

/usr/sbin/ndd -set /dev/ge instance 0  
/usr/sbin/ndd -set /dev/ge adv_1000fdx_cap 1  
/usr/sbin/ndd -set /dev/ge adv_1000hdx_cap 0  
/usr/sbin/ndd -set /dev/ge adv_pauseTX 1  
/usr/sbin/ndd -set /dev/ge adv_pauseRX 1  
/usr/sbin/ndd -set /dev/ge adv_1000autoneg_cap 0

/usr/sbin/ifconfig ge0 105.15.15.235 netmask 255.255.255.0

But after a network switch upgrade, server2 couldn't establish link with the switch; we tried to reboot server2, then after a couple of days the rsh starts not functioning. Also later we found out that setting /usr/sbin/ndd -set /dev/ge adv_1000autoneg_cap to 0 is causing the problem between the switch and server. We have to set it to 1 to solve the problem.  

Now it gets so contradictary that it is hard to know what is the real cause. Any advice?
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Expert Comment

by:neteducation
ID: 13880084
You write "it worked fine but then suddenly break off"

do you mean in the middle of the transmision? or do you mean it worked until day x and since then it's no longer working ?
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Author Comment

by:ebi168
ID: 13880143
Actually rsh -l tom 43.5.34.67 works now but if we pass a command, it hangs: rsh -l tom 43.5.34.67 test.sh
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Expert Comment

by:neteducation
ID: 13880277
i suppose

ping 43.5.34.67

will work.

What about

ping 43.5.34.67 10000

? (ping with payload)
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Author Comment

by:ebi168
ID: 13880507
neteducation: it no longer works after that day.
0
 

Author Comment

by:ebi168
ID: 13880536
I don't what does ping 43.5.34.67 10000 mean, but the result is 43.5.34.67 alive.
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LVL 10

Assisted Solution

by:neteducation
neteducation earned 2000 total points
ID: 13880660
ping 43.5.34.67 10000

mean that you send ping-packets with a dataload of 10'000 bytes (instead of 64 bytes which is the default)

This is to test if communication works with low traffic and stops at "high" traffic.

Doesn't seem to be the problem though.
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LVL 10

Assisted Solution

by:neteducation
neteducation earned 2000 total points
ID: 13880727
Try the following:

On server 2:

snoop server1 server2


Then on server 1

rsh -l tom server2

and

rsh -l tom server2 test.sh


and see what snoop says on server 2.

is there traffic between the servers, when starting the version with test.sh

oh yes, and what about a simple

rsh -l tom server2 ls

does it hang too, or does this come through ?
0
 

Author Comment

by:ebi168
ID: 13880947
rsh -l tom server2 ls
rsh -l tom server2 /usr/bin/ls
rsh -l tom server2 ksh ./usr/bin/ls

the above all hangs!
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Author Comment

by:ebi168
ID: 13880960
Before I try snoop, how can I stop it afterwards.
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Expert Comment

by:neteducation
ID: 13881039
just press <ctrl> c to stop snoop
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Author Comment

by:ebi168
ID: 13881085
This is what I got from rsh -l tom server2 ls
what does it tell:

Using device /dev/ge (promiscuous mode)
server1 -> server2      RSHELL C port=696
server2 -> server1          RSHELL R port=696
server1 -> server2      RSHELL C port=696
server1 -> server2      RSHELL C port=696 695\0
server2 -> server1          RSHELL R port=696
server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>
server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>
server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>
server2 -> server1          ICMP Echo request (ID: 22836 Sequence number: 0)
server1 -> server2      ICMP Echo reply (ID: 22836 Sequence number: 0)
server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>
server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>
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LVL 10

Accepted Solution

by:
neteducation earned 2000 total points
ID: 13881221
seems like your server1 does not accept the connection (on port 695) that server2 and server1 handled out (on line 4 of the snoop)

Do you have some sort of firewall / packet filter active on server 1 ?  
0
 

Author Comment

by:ebi168
ID: 13881233
ok I got more info from snoop:

    aai-sun -> sap          TCP D=687 S=945 Syn Seq=162019920 Len=0 Win=24820 Options=<no
p,nop,sackOK,mss 1460>
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686 (bgaaip@AAIP) aai-su
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 l
     aai-sun -> sap          RLOGIN R port=686 l
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 s
     aai-sun -> sap          RLOGIN R port=686 s
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
     aai-sun -> sap          RLOGIN R port=686 #sai_invoice#
     aai-sun -> sap          RLOGIN R port=686 2
     aai-sun -> sap          RLOGIN R port=686 20
     aai-sun -> sap          RLOGIN R port=686 2005050326143001.log
     aai-sun -> sap          RLOGIN R port=686 2005050328143002.log
     aai-sun -> sap          RLOGIN R port=686 2005050416143000.log
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686 2005050418143001.log
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 l
     aai-sun -> sap          RLOGIN R port=686 l
         sap -> aai-sun      RLOGIN C port=686 s
     aai-sun -> sap          RLOGIN R port=686 s
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 t
     aai-sun -> sap          RLOGIN R port=686 t
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 e
     aai-sun -> sap          RLOGIN R port=686 e
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 s
     aai-sun -> sap          RLOGIN R port=686 s
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 t
     aai-sun -> sap          RLOGIN R port=686 t
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 .
     aai-sun -> sap          RLOGIN R port=686 .
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 s
     aai-sun -> sap          RLOGIN R port=686 s
         sap -> aai-sun      RLOGIN C port=686 h
     aai-sun -> sap          RLOGIN R port=686 h
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686 test.sh\r\n(bgaaip@AAI
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 c
     aai-sun -> sap          RLOGIN R port=686 c
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 a
     aai-sun -> sap          RLOGIN R port=686 a
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 t
     aai-sun -> sap          RLOGIN R port=686 t
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 t
     aai-sun -> sap          RLOGIN R port=686 t
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 e
     aai-sun -> sap          RLOGIN R port=686 e
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 s
     aai-sun -> sap          RLOGIN R port=686 s
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 t
     aai-sun -> sap          RLOGIN R port=686 t
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 .
     aai-sun -> sap          RLOGIN R port=686 .
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 s
     aai-sun -> sap          RLOGIN R port=686 s
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 h
     aai-sun -> sap          RLOGIN R port=686 h
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686 ls -al \r\n(bgaaip@AAI
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 p
     aai-sun -> sap          RLOGIN R port=686 p
         sap -> aai-sun      RLOGIN C port=686 w
     aai-sun -> sap          RLOGIN R port=686 w
         sap -> aai-sun      RLOGIN C port=686 d
     aai-sun -> sap          RLOGIN R port=686 d
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686 /u04/interface/ADP/s
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 p
     aai-sun -> sap          RLOGIN R port=686 p
         sap -> aai-sun      RLOGIN C port=686 w
     aai-sun -> sap          RLOGIN R port=686 w
         sap -> aai-sun      RLOGIN C port=686 d
     aai-sun -> sap          RLOGIN R port=686 d
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686 /u04/interface/ADP/s
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          TCP D=687 S=945 Syn Seq=162019920 Len=0 Win=24820 Options=<no
p,nop,sackOK,mss 1460>
         sap -> aai-sun      RLOGIN C port=686 p
     aai-sun -> sap          RLOGIN R port=686 p
         sap -> aai-sun      RLOGIN C port=686 w
     aai-sun -> sap          RLOGIN R port=686 w
         sap -> aai-sun      RLOGIN C port=686 d
     aai-sun -> sap          RLOGIN R port=686 d
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686 /u04/interface/ADP/s
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 e
     aai-sun -> sap          RLOGIN R port=686 e
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 x
     aai-sun -> sap          RLOGIN R port=686 x
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686 i
     aai-sun -> sap          RLOGIN R port=686 i
         sap -> aai-sun      RLOGIN C port=686 t
     aai-sun -> sap          RLOGIN R port=686 t
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=686
         sap -> aai-sun      RLOGIN C port=686
     aai-sun -> sap          RLOGIN R port=686
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          RLOGIN R port=683
         sap -> aai-sun      RLOGIN C port=683
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          RLOGIN R port=683
         sap -> aai-sun      RLOGIN C port=683 rneighbo\0bgaaip\0vt10
     aai-sun -> sap          RLOGIN R port=683
     aai-sun -> sap          RLOGIN R port=683
         sap -> aai-sun      RLOGIN C port=683
         sap -> aai-sun      RLOGIN C port=683
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          RLOGIN R port=683
     aai-sun -> sap          RLOGIN R port=683 Last login: Wed Apr
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          RLOGIN R port=683 Sun Microsystems Inc
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          RLOGIN R port=683 You have mail.\r\n(bga
         sap -> aai-sun      RLOGIN C port=683
         sap -> aai-sun      RLOGIN C port=683 p
     aai-sun -> sap          RLOGIN R port=683 p
         sap -> aai-sun      RLOGIN C port=683 w
     aai-sun -> sap          RLOGIN R port=683 w
         sap -> aai-sun      RLOGIN C port=683 d
     aai-sun -> sap          RLOGIN R port=683 d
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          RLOGIN R port=683
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          RLOGIN R port=683 /u04/interface/ADP/s
         sap -> aai-sun      RLOGIN C port=683
     aai-sun -> sap          TCP D=687 S=945 Syn Seq=162019920 Len=0 Win=24820 Options=<no
p,nop,sackOK,mss 1460>
     aai-sun -> sap          RSHELL R port=688
         sap -> aai-sun      RSHELL C port=688
0
 

Author Comment

by:ebi168
ID: 13881247
seems like your server1 does not accept the connection (on port 695) that server2 and server1 handled out (on line 4 of the snoop)

Do you have some sort of firewall / packet filter active on server 1 ?  

How do you tell it is server 1 has the problem? I need to check with server 1 about the firewall thing. Thanks
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LVL 10

Expert Comment

by:neteducation
ID: 13881261
ok, this second output was from a rlogin sesion (that is, if you do rsh -l tom ai-sun without a command)

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LVL 10

Expert Comment

by:neteducation
ID: 13881273
>>>> server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>
>>>> server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>
>>>> server2 -> server1          TCP D=695 S=947 Syn Seq=4256014796 Len=0 Win=24820 Options=<n
op,nop,sackOK,mss 1460>

....

Here Server2 is trying to Contact Server1 on port 695.... but does not get any answer.
0
 

Author Comment

by:ebi168
ID: 13881291
No, even I don't do any rsh thing (just snoop), there are things moving: including things I typed on server2 and not intend to communicate with server1.
0
 

Author Comment

by:ebi168
ID: 13881301
It does get response if you look at my second paste of snoop output.
0
 
LVL 10

Expert Comment

by:neteducation
ID: 13881328
let me guess....

you are physically sitting at server1 and connected to server2 over rlogin or rsh (without command)

then you started snoop on server 2 thrugh the session above.

-> the data is being transmitted over the network, which is where snoop sees it.
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Author Comment

by:ebi168
ID: 13881341
I telnet to server2, which is in our LAN and I have get into server1 (hundreds of miles away) using putty.
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Author Comment

by:ebi168
ID: 13881450
Ok I got something cleaner. I issued rsh -l tom server2 /usr/bin/pwd, here is the snoop result. Would you again confirm me that there is firewall issue with server 1:

sap -> aai-sun      RSHELL C port=647
     aai-sun -> sap          RSHELL R port=647
         sap -> aai-sun      RSHELL C port=647
       sap -> aai-sun      RSHELL C port=657 656\0
     aai-sun -> sap          RSHELL R port=657
     aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
     aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
     aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
     aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
     aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
     aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
     aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
aai-sun -> sap          RSHELL R port=657
         sap -> aai-sun      RSHELL C port=657
         sap -> aai-sun      RSHELL C port=657
     aai-sun -> sap          RSHELL R port=657
aai-sun -> sap          RSHELL R port=657
         sap -> aai-sun      RSHELL C port=657
         sap -> aai-sun      RSHELL C port=657
     aai-sun -> sap          RSHELL R port=657
aai-sun -> sap          ICMP Echo request (ID: 27078 Sequence number: 0)
         sap -> aai-sun      ICMP Echo reply (ID: 27078 Sequence number: 0)
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Author Comment

by:ebi168
ID: 13881507
Ok, I think it is not network issue since we can do rsh -l tom server2. Problem only comes when we try to issue a command before we login to that server: rsh -l tom server2 command. Maybe this is a permission problem. Just not sure how to solve it now.
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Assisted Solution

by:neteducation
neteducation earned 2000 total points
ID: 13883183
yes, right....
all those

  aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
  aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
  aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
 
packets are server aai-sun trying to reach server sap, but dont get an answer.
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Author Comment

by:ebi168
ID: 13887532
But then how come we could do rsh -l user host (without passing the command). If the network has problem, this one shouldn't even go through, right?
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Assisted Solution

by:neteducation
neteducation earned 2000 total points
ID: 13887539
rsh -l user host (without command)  is actually using a different Protocol, it's using RLOGIN, not RSHELL
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Author Comment

by:ebi168
ID: 13887597
So you think the firewall will affect differently between RLOGIN and RSHELL. What is their security level difference?
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by:neteducation
neteducation earned 2000 total points
ID: 13887649
RLOGIN is using one tcp-connection: the one from the client to the server (that is started with the command), that is used for data communication.

RSHELL is using two tcp-connections: One from the client to the server (that is started with the command), that is used for controlling information and a second one from the server to the client (dynamically handled out between server and client) that is used for data communication (stdin / stdout from the remote task being redirected to the local machine). You could also say that this second connection is kind of the same as the first in the RLOGIN-Protocol.
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Author Comment

by:ebi168
ID: 13887689
Great! So what exactly is causing RSHELL to fail while RLOGIN succeed.
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Author Comment

by:ebi168
ID: 13887752
"all those

  aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
  aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
  aai-sun -> sap          TCP D=656 S=941 Syn Seq=861680968 Len=0 Win=24820 Options=<nop,nop,sackOK,mss 1460>
 
packets are server aai-sun trying to reach server sap, but dont get an answer."

---
What are these lines doing:
-sending packet and expecting a confirmation of accepted
or
try to establish connection before sending a packet?
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by:neteducation
neteducation earned 2000 total points
ID: 13887763
in RSHELL they make up this second connection, and (as I suppose your firewall) is not allowing this. In RLOGIN there is no such second connection, therefore the firewall cannot forbid it.
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by:neteducation
neteducation earned 2000 total points
ID: 13887790

>> What are these lines doing:
>> -sending packet and expecting a confirmation of accepted
>> or
>> try to establish connection before sending a packet?

They try to establish a connection (Syn means Synchronize, which should be Answered by Syn/Ack which means Acknowledge your SYN request, also want to Syn, which again should be answered by Ack, acknowledging the the second Syn. After this the TCP-Session is built up and both partys can start sending data .
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Author Comment

by:ebi168
ID: 13887906
I will have a serverA guy look into this.
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Expert Comment

by:neteducation
ID: 13887948
oh, yes... you mentioned somewhere that serverA is somewhere far away.... so it might as well be blocked on a firewall between the two  (actually I think it's even more likely).

If it is a firewall in between, then may the easiest is to go for ssh (as seen in your other question)

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Author Comment

by:ebi168
ID: 13888116
So if later we find out it is really caused firewall, is it possible to fix it still using rsh (ssh needs management decision).
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Author Comment

by:ebi168
ID: 13888193
If it is a firewall in between, then may the easiest is to go for ssh (as seen in your other question)

--could you explain?
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Author Comment

by:ebi168
ID: 13888202
So this means both server need to have ssh?
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Expert Comment

by:neteducation
ID: 13888206
that's depending on the kind of firewall you use. The firewall must support it.

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Author Comment

by:ebi168
ID: 13891154
neteducation: Thank you for the good work. The problem has been solved. ServerA has opened some ports.
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Expert Comment

by:neteducation
ID: 13891263
great, thanks for the feedback
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