What are the previous and current version of the jabber-plugin (the plugin doesn't get automatically updated if Jenkins is)?
Is _xmpp-client._tcp.jabber.peykasa.ir the correct name of your Jabber server? What happens if you try to resolve the name (i.e. nslookup) from the shell on the Jenkins host?

jabber-plugin version is 1.28
The jabber server address is jabber.peykasa.ir
and _xmpp-client._tcp.jabber.peykasa.ir cannot be resolved by using ping command.
Below response belongs to ping command:

"ping _xmpp-client._tcp.jabber.peykasa.ir
ping: unknown host _xmpp-client._tcp.jabber.peykasa.ir"

I'm pretty sure this problem has happened after upgrading jenkins to this version.
So I will be thankful if you consider this issue and try to solve my problem though.

Thanks in advance.

I'd suspect that the DNS SRV setup for your XMPP server might not be correct. Check e.g. http://blog.teemu.im/2008/12/14/setting-your-srv-records-straight-for-xmpp/

Have you ruled out that nothing else in the infrastructure has changed?
Can you connect with a different XMPP client from the Jenkins host?

Also possible that Smack API 4.x broke something which was working previously...
Does maybe your Jabber server use the older _jabber._tcp. name?
This seems to be broken in Smack 4.x. See https://github.com/igniterealtime/Smack/commit/2eb13f48d2a72af9f0e88c5b2d8a9881a655fa1b#commitcomment-8506196

Smack issue tracked in https://igniterealtime.org/issues/browse/SMACK-616

This build of the plugin uses a version of the Smack library which could fix the issue:
https://dl.dropboxusercontent.com/u/25863594/jabber.hpi

Would be great if you could test it

Mohammad, any update on this?
If you don't have the time/resources to test it, please let me at least know.

Kutzi,
I am using smack 4.0.5 in my project, and tested jars of version 4.0.6-SNAPSHOT and worked.

But, using openfire is required to disable the security in code, because I dont know how to disable security in openfire 3.9.3

Example works fine.
ConnectionConfiguration config = new ConnectionConfiguration ("localhost");
config.setSecurityMode (SecurityMode.disabled);
XMPPConnection con = new XMPPTCPConnection (config);
con.connect();

Anyone have an example of how to generate and import certificate in openfire or other xmpp server and a code sample using SSL and Smack?

The code and exception:
XMPPConnection con = new XMPPTCPConnection ("localhost");
con.connect();

WARNING: Exception while resovling SRV records for localhost. Consider adding '_xmpp-(server|client)._tcp' DNS SRV Records
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
Nov 23, 2014 10:40:05 PM org.jivesoftware.smack.tcp.PacketWriter writePackets
WARNING: Exception writing closing stream element
java.net.SocketException: Socket closed
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:121)
at java.net.SocketOutputStream.write(SocketOutputStream.java:159)
at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:295)
at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:141)
at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229)
at java.io.BufferedWriter.flush(BufferedWriter.java:254)
at org.jivesoftware.smack.tcp.PacketWriter.writePackets(PacketWriter.java:190)
at org.jivesoftware.smack.tcp.PacketWriter.access$000(PacketWriter.java:40)
at org.jivesoftware.smack.tcp.PacketWriter$1.run(PacketWriter.java:77)

Thanks.

Same problem here with "Jabber notifier 1.30" and "Jenkins 1.590".
Thanks.

Fixed in upcoming release 1.31