Server dependencies


 
Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers Server dependencies
# 1  
Old 06-03-2012
Server dependencies

Hi,
How can I discover server dependencies? For example, how do I find out what services depend on email? Is it with nmap?
Thanks!
Smilie
# 2  
Old 06-03-2012
Hi,

not very clear what are you really looking for, but maybe this can help:
If you're trying to look for what network services the server is acting as a client (that is, applications running on the server that are acting as clients with regard to some network services):
1. netstat: look at external ports/services the server has in state ESTABLISHED or CLOSE_WAIT; run this command if you have a login account on the server. You could find services provided by the server itself (i.e. applications from the monitored server connecting to TCP/UDP sockets on the server itself).
2. a network traffic sniffing tool (i.e. tcpdump, wireshark, etc.) may also do the job, provided they are run for a sufficiently long time (many applications may have permanet traffic with external services while others may just connect once in a while). You don't have to run tcpdump or wireshark on the machine itself, as long as you have a machine in the same subnet as the server you are monitoring with a network interface capable of 'promiscuous mode'.

When you asked for nmap usage, remember that nmap is generally used to discover what network services are listening on the target server. Unless you run nmap on the target server itself, the results returned by nmap may be less comprehensive than the results returned by running netstat (this time, you would look to results with TCP/UDP sockets in state LISTENING), because a firewall may filter some sockets.

see ya
fra
This User Gave Thanks to frappa For This Post:
# 3  
Old 06-03-2012
Bug Server dependencies

Quote:
Originally Posted by frappa
If you're trying to look for what network services the server is acting as a client (that is, applications running on the server that are acting as clients with regard to some network services):
For example, the web server depends on DNS. But I'm not sure if the web server would be a DNS client?

Quote:
Originally Posted by frappa
netstat: look at external ports/services the server has in state ESTABLISHED or CLOSE_WAIT; run this command if you have a login account on the server. You could find services provided by the server itself (i.e. applications from the monitored server connecting to TCP/UDP sockets on the server itself).
But how do you identify services a server is a client for? Is it if the port is not a common port number?

Basically, I need to find out about server relationships- how to identify what services a server is dependent on. Like how to use CLI for example to find out that email depends on DNS.

Thanks, I appreciate any help!
# 4  
Old 06-04-2012
Hi,

sorry for not being too clear.

netstat can be used in order to look both for services provided by the monitored server and external services for which the server is acting as a client.
Actually netstat output reports both 'Local address' and 'Foreign address' columns: the former is for local network sockets, while the latter is for 'external' network sockets.
When I stated "[...]You could find services provided by the server itself[...]", I meant that you could discover services for which the server is acting both as a server and as a client (trivial case: think about SSHing to the server itself).

I also didn't mention that for UDP traffic for which the server acts as a client with respect to an external service provide, you may never see a corresponding row in netstat output, because UDP connections are stateless by design (for exceptions have a look at: networking - netstat -na : udp and state established? - Stack Overflow that is, netstat output will show UDP sockets just for services for which the server is actually acting as a server.
So, in order to see if an application is using DNS (implemented as a service listening on UDP port 53 on the server side) you'd better use a network traffic sniffing tool.

see ya
fra

Last edited by frappa; 06-04-2012 at 04:51 AM.. Reason: correcting some typos
# 5  
Old 06-04-2012
Server dependencies

Thanks Frappa, that was very helpful and clear. Smilie
 
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. AIX

Dependencies errors

Hi guys when I'm trying to install some RPMs file I got this errors # rpm -ivh DSM-IBMAIXServer-7.2-796075.noarch.rpm error: failed dependencies: perl(Digest::MD5) is needed by DSM-IBMAIXServer-7.2-796075 perl(Exporter) is needed by DSM-IBMAIXServer-7.2-796075 ... (1 Reply)
Discussion started by: khaled_ly84
1 Replies

2. Red Hat

RPM failed dependencies

I'm trying to package the latest Oracle JDK (1.7.0_51) into an RPM. Packaging works fine but when i try to install via rpm -Uvh xxx.rpm, i get the following: #sudo rpm -ivh Sun_JDK7-1.7.0-51.x86_64.rpm error: Failed dependencies: libavcodec.so.52()(64bit) is needed by Sun_JDK7-1.7.0-51.x86_64... (3 Replies)
Discussion started by: asc123321
3 Replies

3. Linux

Failed dependencies

Hi all, i'm trying to upgrade pandorafms to the new version 4.0.3-130118, actually i have installed on my machine the version 3.0.0-8.1.el5, the error i'm getting when trying to update its the following rpm -Uvh pandorafms_agent_unix-4.0.3-130118.noarch.rpm error: Failed dependencies: ... (1 Reply)
Discussion started by: charli1
1 Replies

4. UNIX and Linux Applications

Help me | RT Installation and its dependencies

Hello everyone, This is my problem: I'm installing RT (Request Tracker) when I found the firsts difficulties with package that must be configured. I could resolve them :). The real problem are the missing dependencies. The command perl -MCPAN -e"install denpendency" resolved some missing... (0 Replies)
Discussion started by: journey
0 Replies

5. Red Hat

RPM dependencies fail

Hello, I am trying to install krb5-libs-1.4-4.pp-rh73.i386.rpm on my Red Hat 7.X server, however while installing/upgrading it fails due to dependencies. I checked for these dependencies and i already found them on the server. I wonder why it is giving these errors. I tried copying these... (1 Reply)
Discussion started by: sunny_a_j
1 Replies

6. Red Hat

problem with Dependencies package !

Dear Friends , I am using RHEL 5 server . In Linux when I am going to install 'mod_ssl' rpm then I got the following error : # rpm -ivh mod_ssl-2.2.3-6.el5.i386.rpm --aid --force warning: mod_ssl-2.2.3-6.el5.i386.rpm: Header V3 DSA signature: NOKEY, key ID 37017186 error: Failed... (5 Replies)
Discussion started by: shipon_97
5 Replies

7. Red Hat

RPM and dependencies OPENSSH

Hello Sorry, I am not to well versed in RHE and I am having some issues. I have doen a cursury look around and could not find an answer. I have 2 RHE4 servers. Both have old versions of OPENSSH along with , server, askpass, askpass-gnome, etc. I cannot upgrade to our new pkg release of... (8 Replies)
Discussion started by: mhenryj
8 Replies

8. Solaris

Software Dependencies Conflicts

Question: What do you do when you have a software dependency conflict? Case in point, according to Freeware for Solaris, before one can install tcl, tk must be installed first. And then when I go to investigate dependencies for tk, it says that tcl must be installed first!!! Its like... (2 Replies)
Discussion started by: RobSand
2 Replies

9. Solaris

Determinining Software Dependencies

How does one determine what software dependenices are required for a software package? I looked up the command pkginfo in the man pages, but could not find anything to answer this question... Thanks Rob (1 Reply)
Discussion started by: RobSand
1 Replies

10. UNIX for Advanced & Expert Users

Cksum dependencies

Hi, On what factors does the cksum depend. If i build 2 machines exactly the same, then can i get the checksum of 2 compiled files same. Thanks (3 Replies)
Discussion started by: vibhor_agarwali
3 Replies
Login or Register to Ask a Question