Linux - NewbieThis Linux forum is for members that are new to Linux.
Just starting out and have a question?
If it is not in the man pages or the how-to's this is the place!
Notices
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use.
Exclusive for LQ members, get up to 45% off per month. Click here for more info.
I'am able to connect between two machines via ssh on port 22.But when i am doing the traceroute to my 2nd machine from my first machine , it is reporting the below error
Can someone please help in understand that why is it so , if i'm able to do ssh to my second machine that means it is reachable via the network then why my traceroute is showing asterick(*) even when i have disabled the firewall
You haven't told us anything about your network topology. I assume that your machines are connected within the same subnet on a LAN? Then traceroute won't show any gateway hops, since the destination is directly reachable (resolved by ARP), so the traceroute packets are sent directly to the host in question. Since the router is not needed to route the packet, it won't show up as a hop. Now why your target host rejects the ICMP packets sent is a another matter again. I would review 'man traceroute' for other options.
Similar question asked here that might answer your question. Note the last comment to making sure that UDP ports are allowed (which traceroute uses by default). BTW, if you read the man page for traceroute, you'll note that it is possible to test with other protocol types, including the -T option for probing with TCP SYN packets.
Traceroute works by generating ICMP traffic - starting with a timeout of 1, then it waits for a return ICMP packet with "time exceeded" status from a gateway. Then it increments the count, and tries again.
If no reply after a rather long timeout, it will increment anyway, and try (this is reported with the *).
If the network has ICMP disabled, then you never get a reply.
The manpage on traceroute lists several alternatives to try to handle that:
-T option, to use TCP, the default target port is 80 (so if the target doesn't have a web server it doesn't work well - try other ports, 22, or whatever you used for a known service...)
-U option, to use UDP.
In both cases, random data is sent, so sometimes the service on the target could get confused...
LinuxQuestions.org is looking for people interested in writing
Editorials, Articles, Reviews, and more. If you'd like to contribute
content, let us know.