Goat Rodeo Cowboy nailed it, as he does in most of his posts.
It is not illegal or immoral to keep the "lines of communication" open with other "opportunities." However, use extreme caution if you have put the word out there, especially in the same city or area you are currently employed.
Also, the wording of your contract either describes (or doesn't) whether you face consequences for any effort deemed to be construed to "break your contract" without permission of your employer.
Some employers DO give permission to talk with other "opportunities" and do not hold that against your contract. It's not their business who you talk to.
However, if you have a contract with a non-compete, it's best to only seek opportunity that is outside the area -- usually 25 miles or more (depending on the market of dominant influence) before you start contacting those who might just call your employer.
Also, GRC is right ... it is expressly important that you include the verbage, without any other disclosure or reason, that you are under contract and that it would be appeciated that no contact be made with your present employer.
Professional courtesy asked in confidence (another key word, "confidential") could go a long way to protect your interests and those of another employer.
Read and re-read any "non-compete" verbage, however, before putting yourself out for possible repercussions.
If worse comes to worse ... and you are really unhappy, a better way may be to go to your employer and ask (don't tell,) that you may have an opportunity to investigate and that you would like permission to explore that option. You don't have to tell where, what, where, when or why.
If you get "tacit approval" to do so ... you will at least have covered your butt. Then, if the employer wants to terminate your contract, you should look at it and read carefully what its "out clause" truly is.
Good luck. And be careful with posting such information ... one never knows who's lurking who could turn the tide against your job search. Stranger things have happened.