PING fails but rlogin works.

[david_252]

Team:

I have a situation here where i am able to rlogin to a box but pinging the box hangs? what would be the reason.

Thanks

David.

[T Dockery]

Firewall blocking ICMP?

[Pete Randall]

Name resolution? Try nslookup by both name and ip. Try ping by both name and ip. Try rlogin by both. Any differences?


Pete

[Massimo Bianchi]

Possible causes are:

- firewall blocking icmp traffic (nowadays very possible, with all these viruses)

- icmp dropped on the hpux hosts (check with ndd)

Massimo

[david_252]

Name resolution looks fine. already checked.

Thanks

David.

[Pete Randall]

David,

Since you've already checked on name resolution, the only other answer I can think of is to check the firewall.


Pete

[david_252]

Thanks Pete:

Since i am logged in to the box right now, is there a way i can check for the firewall?

Thanks

David.

[Pete Randall]

David,

I think you would have to login to the firewall to find out if it's blocking ICMP packets. Is this only one host that you can't ping? Is the unpingable host local or outside the firewall? Have you checked nslookup?


Pete

[david_252]

there are in fact two boxes with the same problem. even if i login to them from the console it hangs a long time before i get the root prompt. but the nslookup works fine both ways

Thanks

David.

[GK_5]

Firewall is blocking ICMP packet. Check Firewall rules.

[Pete Randall]

Hanging on console login is usually something like NFS or NIS issues, but that wouldn't affect ping. Do you have NFS mounted home directories or use NIS?


Pete

[T Dockery]

Can you ping the system from its own console? Not localhost (127.0.0.1), but its network IP.

[david_252]

Ok. I got a confirmation from the network guys that they are blocking ping. The two nodes which does not work, one is a nis master and other one nis client. i login to these servers and type rlogin then i get network unreachable message. Please help

Thanks

David.

[Steven E. Protter]

If ping is blocked, they have taken away one of you good basic network tools.

You might try traceroute, but I bet thats blocked too.

Post the output and makesure its at least stopping at the firewall and not someplace else.

These network guys need to be trained to document and notify prior to making changes.

SEP

[Giri Sekar. · Accepted solution]

David:

If you are running 11.0 then you may do this..

1. netstat -rn (pick up your gateway from the default column)

2. route delete default

3. netstat -rn (you should not see the gateway now)

4. ndd -set /dev/ip ip_ire_gw_probe 0

(this will make sure that your host will not ping the router (which it will do otherwise every 5 minutes))

now set the default gateway back as hop 1

5. route add default 1
(note the 1)

6. netstat -rn (you should be able to see the gateway again)

Now you should be able to reach the network and hopefully you might not see the network unreachable message.

Thanks

Giri Sekar.

[david_252]

Thanks a lot. I am able to reach all the systems now.

Thanks

David.