I just set up eduroam on my laptop and this morning when I fired up my terminal, I noticed that my hostname has been changed most probably by the eduroam set up to a new value. Any ideas why or how this happens?
You're going to get a new hostname every time you join a new network (at least potentially). The hostname identifies the computer and is therefore assigned by the network that you connect to. This usually happens as part of DHCP, where you get an IP address and routing information.
This is perfectly normal and nothing to worry about. If you absolutely need a certain hostname, talk to the network administrators.
Related
I am using Putty to ssh into some of the servers that I work on. I am able to connect all others except the one. Although I was able to connect to it before. Whenever I try connecting to it, it always give me error:
Unable to open connection on myhost: Host does not exist
My firewall is off and I have even re-installed putty but that did not fix it. When I tried connecting to the same server using putty on some other windows system, I was able to do so. I searched regarding this on Internet but did not find much relevant.
I am running putty on Windows 7.
What can be the possible issue?
As I understand you have three computers involved. At the same time one connection is working and the other one fails. So we can exclude that the ssh daemon on your linux box is hanging.
In lack of knowing their real names I will call your computers linuxbox (this is the computer you want to ssh into), win7ok (that is the computer that you are able to ssh from using putty) and win7fail (that obviously is the computer you can't connect from).
Please do a tracert from both Win7 computers:
tracert linuxbox.your.domain
tracert linuxbox
Add the results to your question as it will help us find out what is happening.
Perhaps it is also a good idea to determine the ip address of the linuxbox from win7ok:
ping linuxbox
or
nslookup linuxbox
Then try to connect from win7fail by using the ip address of the target computer, perhaps it is only a DNS problem (which might be as nmap is failing too).
To make all of this easier to understand for us please provide the real names of the computers as you use them in putty.
For me the problem was with the Url of the reposity. Check remote URL. It must start with git#github.com, not https://.
I used nslookup and then used the ip address it gave me to connect and it worked
I had a similar problem with GitExtensions. The solution was to remove the https url and replace it with git#gitlab....
WRONG:
GOOD:
I just went through this. I have a Cisco VPN I need to use to get through to the Linux machine I wanted to login to and check.
No Putty session would get through using the machines name.
An nslookup on the windows machine yielded the correct address.
I too connected right in via the ip address.
I tried to Google the error and it failed, so I suspected the wireless.
Disconnected and reconnected my WiFi and all was good.
I did it fast enough that open connections stayed open.
And new connections refering to DNS names worked fine.
Seems like maybe some cached DNS addresses were stale.
Your DNS cache stores the locations (IP addresses) of web servers that contain web pages which you have recently viewed. If the location of the web server changes before the entry in your DNS cache updates, you can no longer access the site.
Following CLI command will do the trick:
ipconfig /flushdns
I have a computer at my college that I always ssh into from my laptop. However, I'm leaving for break soon, and I realize that whenever I try to ssh in from a different network, the server won't let me in. I really would like to be able to ssh into this computer during break, so what should I do?
Whenever I type this into terminal:
XXXXXXXXXX$ ssh -X XXXXXXX#XXXXX.XXXXX.XXXX.XXX.XXX
The process either won't go forward, or I get this error message:
ssh: Could not resolve hostname XXXXX.XXXXX.XXXX.XXX.XXX: nodename nor servname provided, or not known
Yes, you can, thru ssh-tunnelling. See this link.
The problem is that, you need to have a box of public fixed IP address outside of your school.
If you have a public floating address, it's still possible. First, you will need DDNS (just search 'DDNS' on the web), or other method for your server to get your client's IP address. For example, in your personal web page, somewhere, stores your current client's IP floating IP address. Then, you need a script/program to fetch that address. After that, apply the same ssh-tunneling technique. (Yet, you need a script/program to automatically apply all these steps, yet fail safe issue: When your client's is disconnected, your ssh-tunnel will break, and your ssh-tunneling process died. Your script need to sense it and re-launch (after getting the new floating IP address).
Oh, the pre-assumption is that, you need to be able to ssh from your school server (your linux box in school) to an outside server (a linux box in your home, for example). I think most school won't block ssh access to servers outside of the school.
I'm working with marklogic database and I tried to create a cluster.
I already have a development key. The OS is the same in all the nodes (win 7 x64).
When you tried to add a node into the cluster, you need to type the host name or the IP adress. For some reason when I type de host name, marklogic sometimes can't find the node , but that doesn't matter, because with the IP, the connection is successfull.
The main problem is when continues trought the process. At the end when marklogic try to transfer cluster configuration information to the new host, the process never ends and finally a message like "No data received" appear in the web browser.
I know that this message doesnt mean that the process fails, because when I change for example the host name, the same message appear.
So, when I check the summary in the first node, the second node appears, so that means the node "joins" into the cluster, but I'm not able to start the admin interface and always the second node appears disconnected even if I restart the service.
Aditionally, I'm able to make a ping from any computer to another.
I tried to create another network, because in my school some ports are not allowed, furthermore I tried to use different development key and the same key in my nodes too,
and finally I already have all the services enabled, but the problem persist.
Any help or comments would be appreciated.
Make sure ports 7998 - 8003 are open on both computers for both inbound and outbound traffic and that you don't have a firewall (Windows firewall, or iptables) blocking these.
You can also start looking into the Logs/ErrorLog.txt file and see if something obvious shows up.
Stick to IP addresses for now as it seems your DNS isn't fully working.
Your error looks like a kind of networking connectivity problem between the hosts.
Also you might get more detailed, or atleast different, answers from the MarkLogic developer mailing list.
http://developer.marklogic.com/discuss
-David Lee
Make sure the host names in MarkLogic configuration match the DNS names at which the hosts can see each other. If those are unreliable, then simply use IP addresses as host names. Go to the Admin interface on both ends, lookup the host name, change the DNS name into IP name, try again.
Also look at DALDEI's suggestion about ports and firewalls, that could be interfering as well.
HTH!
This is probably incredibly simple and I'm just missing one step. The problem I was (originally) trying to solve was how to get a statically allocated hostname, one that would not change with each restart. I've done the following steps:
I have a domain registered on GoDaddy, and it points to my EIP. I use it to connect over SSH (putty) to my EC2 instance, so I know that part is working. I've opened ports 9080, 9060, 9043, and 9443 as well as SSH and FTP ports. And I've installed and started the software that uses those ports, and that stuff normally just works on a local RHEL install, so I think what's different here is the custom domain name.
I've added my EIP and fully qualified host name to my /etc/hosts file.
I've added my fully qualified host name to my /etc/hostname file and modified the /etc/rc.local script to set the hostname properly on a restart, and that works. If I execute the command hostname, it returns my fully qualified hostname, so that looks ok.
I cannot ping my server, but I think that's ok, because probably amazon blocks pings. So I don't think that's a symptom of anything.
I cannot open a to http://myserver.mydomain:9080/, which normally just works. Here it just times out.
If I do a wget http://myserver.mydomain:9080 from inside the EC2 instance, it returns failed: No Route To Host
But if I do a wget against localhost instead of the fully qualified name I get what I expect as a response.
So.... routing tables? Do those need to change? And if so how?
You probably don't want to do what you did. Everything in EC2 is NAT'd. Meaning that the IP assigned to your instance is a private/internal ip and the public IP is mapped to it by the routing system.
So internally, you want everything to resolve to the private IP, or you will get charged for traffic as it has to get routed to the edge and then route back in. Using the public DNS name will resolve correctly from the default DNS servers.
If you are using RHEL, you will need to make sure both the security group and the internal firewall (iptables) have ports opened. You could just disable the internal firewall since its a bit redundant with the security groups. On the other hand, it can provide some options security groups do not if you need them.
I have looked this up and what was described in other answers did not work for me. I created a elastic ip from my ec-2 dashboard, and I set the A records of my domain (www, *, and #(none)) but it does not work. When I try to go directly to the ip address it also does not work though so I am not sure why this is happening.
Also where exactly does the elastic ip point? To my home folder, to the ec-2 user? It is not working now so I couldn't test it, but when it does work I still won't know.
Two things: remember that your domain will need to propagate, so leave it a few hours. Also, your elastic IP points to the machine you bound it to.
Almost forgot, you also need to edit your security zone to open up ports to allow incoming connections on those ports, as the default is to block everything except SSH.